Materials for lithium-ion battery safety

Gel polymer electrolytes for room-temperature sodium sulfur batteries

Sodium sulfur batteries have gained attention owing to their advantages of low cost and high specific capacity. However, the current electrolytes have a few main disadvantages including sodium-dendrite growth, sulfur shuttling and electrolyte leakage, which hinder their practical application. Herein, we report the preparation of poly(vinylidene fluoride-co-hexafluoropropylene)-based gel polymer electrolytes using a simple solution casting technique for room-temperature sodium sulfur battery applications. The gel polymer electrolyte was activated by soaking the freshly prepared gel polymer membranes in a liquid electrolyte solution. Our gel polymer electrolyte exhibited a high ionic conductivity of 1.37 mS cm-1 at ambient temperature, with an electrochemical stability window of 4.5 V versus Na+/Na. Furthermore, sodium symmetric cells showed stable stripping/plating of Na+ up to 3000 hours, with a transference number of 0.648. The cells achieved a specific capacity of 398 mA h g-1 for the initial reversible discharge specific capacity and 75 mA h g-1 at cycle 200 with 99.9% coulombic efficiency at 0.1 C rate. Our results demonstrate that these polymer electrolytes are potential candidates for sodium sulfur batteries with desired performance.

Engineering Carboxyl Content in Aqueous Core-Shell Emulsions for Efficient Inorganic Coated Separators Enhancing Lithium-Ion Battery Safety Performance

Polypropylene separators (PP) are widely used in lithium-ion batteries due to good electrochemical stability and low cost. However, PP separators are prone to thermal shrinkage at high temperatures, resulting in short circuit of positive and negative electrode contacts and thermal runaway. In this work, a waterborne core-shell emulsion binder rich in carboxyl and ester groups with both strength and adhesion is designed and coated with alumina (Al2O3) as a composite coating on the PP separator. Due to the good adhesion of the emulsion binder to the Al2O3 and the PP separator, the separator has excellent dimensional stability at 120 °C, while the thickness of the separator only increases by 2.5 μm. With the help of the dissociation effect of the ester group on the lithium salt and the lithium ion conduction characteristics, the composite separator improves the ionic conductivity (0.82 mS/cm) by 25 % compared with the PP separator and the lithium ion transference number reaches 0.47. The cycling capacity of the lithium-ion battery with the composite separator is 8.62 % higher than that of the PP separator after 100 cycles. The performance changes of acrylic acid as a functional monomer on emulsion binders and composite separators are further investigated.

Ptychographic Observation of Lithium Atoms in the Irradiation-Sensitive Garnet-Type Solid Electrolyte at Sub-Angstrom Resolution

Garnet-type solid electrolyte cubic Li7La3Zr2O12 (c-LLZO) emerges as a promising candidate for establishing reliable and high-performance lithium-ion batteries. Its extreme sensitivity to electron irradiation poses a significant challenge in atomically resolving its structure using conventional transmission electron microscopy (TEM) techniques. We demonstrate that the combination of low-dose four-dimensional scanning TEM (4D-STEM) with multislice ptychographic retrieval methodology manages to achieve a sub-Angstrom resolution and the direct visualization of lithium atoms within c-LLZO. The distribution of lithium in depth direction is also obtained. This work provides atomic-scale insights into the distribution of light elements within irradiation-sensitive dense crystals, paving the way for investigating the microstructure-property relationship.

Battery state of health estimation under fast charging via deep transfer learning

Accurate state of health (SOH) estimation is essential for effective lithium-ion battery management, particularly under fast-charging conditions with a constrained voltage window. This study proposes a hybrid deep neural network (DNN) learning model to improve SOH prediction. With approximately 22,000 parameters, the model effectively estimates battery capacity by combining local feature extraction (convolutional neural networks [CNNs]) and global dependency analysis (self-attention). The model was validated on 222 lithium iron phosphate (LFP) batteries, encompassing 146,074 cycles, with limited data availability in a state of charge (SOC) range of 80%-97%. Trained on fast-charging protocols (3.6C-8C charge, 4C discharge), it demonstrates high predictive accuracy, achieving a mean absolute percentage error (MAPE) of 3.89 mAh, a root-mean-square error (RMSE) of 4.79 mAh, and a coefficient of determination (R2) of 0.97. By integrating local and global analysis, this approach significantly enhances battery aging detection under fast-charging conditions, demonstrating strong potential for battery health management systems.

Critical Perspectives on the Design of Polymeric Materials for Mitigating Thermal Runaway in Lithium-Ion Batteries

During the global energy transition, electric vehicles and electrochemical energy storage systems are rapidly gaining popularity, leading to a strong demand for lithium battery technology with high energy density and long lifespan. This technological advancement, however, hinges critically on resolving safety challenges posed by intrinsically reactive components particularly flammable polymeric separators, organic electrolyte systems, and high-capacity electrodes, which collectively elevate risks of thermal runaway (TR) under operational conditions. The strategic integration of smart polymeric materials that enable early detection of TR precursors (e.g., gas evolution, thermal spikes, voltage anomalies) and autonomously interrupt TR propagation chains has emerged as a vital paradigm for next-generation battery safety engineering. This paper begins with the development characteristics of thermal runaway in lithium batteries and analyzes recent breakthroughs in polymer-centric component design, multi-parameter sensing polymers, and TR propagation barriers. The discussion extends to intelligent material systems for emerging battery chemistries (e.g., solid-state, lithium-metal) and extreme operational environments, proposing design frameworks that leverage polymer multifunctionality for hierarchical safety mechanisms. These insights establish foundational principles for developing polymer-integrated lithium batteries that harmonize high energy density with intrinsic safety, addressing critical needs in sustainable energy infrastructure.

Lewis Acid-Base Synergistically Enhancing Practical Composite Electrolyte for Fluoride-ion Batteries at Room Temperature

Fluoride-ion batteries (FIBs) represent a potential "next-generation" electrochemical storage device, offering high energy density. However, the practical implementation of FIBs at room temperature is impeded by the limitations of currently available ceramic electrolytes. Here, a composite NH4HF2@PEO@β-PbSnF4 electrolyte with both high conductivity of 10-4 S cm-1 and wide electrochemical stability window (4.59 V vs Pb/PbF2) at room temperature is fabricated. Field emission transmission electron microscope (FETEM) demonstrates the presence of a space charge region, which enhances the conductivity. Furthermore, 19F NMR and density functional theory (DFT) calculations elucidate that the interaction between Sn2+ (Lewis acid) and HF2 - (Lewis base) induces significant modifications to the electronic structure, which critically contribute to the enhanced electrochemical stability window of the composite electrolyte. Integrating this promising electrolyte with high-voltage CuF2 cathodes and Pb/PbF2 anodes, a reversible coin cell with a discharge capacity of 143 mAh g-1 up to 50 cycles is demonstrated. The rational design of such composite electrolytes offers a pathway toward the practical application of FIBs at room temperature.

Bi-Layered, Ultrathin Coating Initiated Relay Response to Impart Superior Fire Resistance for Polymeric and Metallic Substrates

Developing high-efficient flame-retardant coatings is crucial for fire safety polymer and battery fields. Traditional intumescent coatings and ceramifiable coatings struggle to provide immediate and prolonged protection simultaneously, which limits the applicability. To address this, an innovative bi-layered coating with organic/nano-inorganic additives is inspired by differential response behaviors, enabling relay response effect with both fast-acting and extended protection. Specifically, two layers function continuously in the form of a relay. With a mere 320 microns, the bi-layered coating withstands fire temperatures of up to 1400 °C for at least 900 s. Consequently, the coating effective prevented burn through in aluminum plates and glass fabric-reinforced epoxy resin, which otherwise were burned through in 135 and 173 s, respectively. Meanwhile, the bi-layered coating suppressed the formation and decomposition of solid interface layer in lithium soft-package batteries, leading to prolonged electrochemical stability and fire safety. Additionally, the bi-layered coating with a fast response endows polyurethane foam with rapid self-extinguishing, preventing ignition even under exposure to strong fire of 1400 °C. Shortly, our work offers new insights into the design and development of thin, high-performance, and multi-application flame-retardant coatings.

Li+-migration influencing factors and non-destructive life extension of quasi-solid-state polymer electrolytes

Polymer-based quasi-solid-state electrolytes (QSSE) are believed to be the most feasible candidates for solid-state batteries, but they are hindered by relatively lower ionic conductivity and narrower electrochemical window. Here, we synthesize a series of ether-free acrylates containing Li+-ligands for high-voltage-stable QSSEs. Our findings demonstrate that the polymer-involved solvation structure is critical in determining the ionic conductivity, and low-temperature crystallization of the polymer can be used for non-destructive life extension of batteries. The prepared polymers do not contain ether unit and exhibit a polymerization degree of 99% in cells without residual double-bonded monomer, endowing them with high antioxidation capability and compatibility with high-voltage positive electrodes including LiNi0.85Co0.075Mn0.075O2, 4.6 V LiCoO2 and 4.8 V Li1.13Ni0.3Mn0.57O2. The confinement of liquid in QSSEs effectively suppresses the interfacial reactions, but the residual interface reactions still gradually consume liquid electrolytes and cause capacity fading, due to the limited diffusion of the confined solvent to wet the interface. Through crystallizing the polymer matrices at -50 °C, the confined liquid in QSSEs is released and re-wets the Li-metal/polymer interface, thereby recovering the capacity and extending the life of solid-state batteries in a non-destructive manner.

MXene-Reinforced Organic-Inorganic Hybrid Protective Layer Enables Dendrite-Free and Ultra-Durable Zinc Metal Anodes

Zn metal is considered a promising anode for aqueous zinc ion batteries (AZIBs) owing to its high capacity and cost-effectiveness. However, dendrite growth, corrosion, and hydrogen evolution occurring on the Zn surface pose significant challenges to achieving stable and reliable AZIBs. Herein, a robust organic-inorganic protective layer, comprising organic zinc alginate (ZA) and inorganic Ti3C2Tx MXene, is fabricated on the Zn anode surface via a simple blade-coating approach. The organic ZA and inorganic MXene synergistically complement each other, with ZA playing a crucial role in inhibiting hydrogen evolution and enhancing electrolyte affinity, while the MXene mitigates severe side reactions, enables uniform Zn2+ deposition, and accelerates electron/ion transfer. Consequently, the ZA/MXene layer (MXZA) facilitates the Zn anode to exhibit remarkable reversibility and stability during continuous Zn plating/stripping, achieving a long-term lifespan of 2500 h at 2 mA cm-2 and 2 mAh cm-2, and 360 h even at 50 mA cm-2 and 50 mAh cm-2 in symmetric cells. When configurated with a sodium vanadate (NVO) cathode, the MXZA@Zn||NVO full cell operates stably with a high-capacity retention of 98.4% over 1000 cycles. This work provides a new perspective on developing efficient surface/interface modifications with synergistic effects toward high-performance zinc metal anodes.

Non-Flammable fluorinated gel polymer electrolyte for safe lithium metal batteries in harsh environments

Compared to liquid electrolytes, gel polymer electrolytes (GPEs) offer enhanced safety and represent an up-and-coming option for high-energy-density lithium metal batteries (LMBs). However, several challenges hindered the practical application of GPEs for LMBs, such as low ionic conductivity at room temperature, decomposition at high voltage, and poor interfacial compatibility with lithium anode. In this study, a non-flammable fluorinated GPE was synthesized using 2,2,2-trifluoroethyl acrylate (TFEA) and ethoxylated trimethylolpropane triacrylate (ETPTA) as precursor materials, with succinonitrile (SN) incorporated as a plasticizer and a dual-salt system of lithium bis(trifluoro-methane) sulfonimide and lithium difluoroxalate borate. Notably, the as-prepared GPE exhibits a high ionic conductivity of 1.33 mS cm-1 at 30 °C, an electrochemical stability window of 5.15 V (vs. Li+/Li), and excellent interfacial compatibility with the high-nickel LiNi0.93Co0.035Mn0.035O2 (NCM-93) cathode and lithium metal anode. Consequently, the Li|NCM-93 cells demonstrated outstanding cycling stability at a cutoff voltage of 4.3 V at room temperature as well as exceptional safety performances under high-temperature conditions and intense radiation conditions. Furthermore, the fluorinated GPE effectively suppresses the gas generation from high-nickel cathode materials and inhibits the growth of lithium dendrites on the anode. This work offers a novel avenue for developing safe and high-voltage solid-state LMBs for working in harsh environments.

Fiber Optic Boltzmann Thermometry in a Doped Halide Double Perovskite for Dynamic Temperature Monitoring in Pouch Cell

Temperature evolution is critical in monitoring the status of Li-ion batteries (LIBs), however, it is a challenge to develop precise thermometry down to the nanoscale regime and instantly detect the internal temperature of pouch-type LIBs. Herein, a Boltzmann type luminescence thermometry is designed and prepared in halide double perovskite Cs2NaLuCl6:Yb/Er upconversion nanocrystals and further fabricate the flexible fluorescence polymer optical fiber (POF) sensor for their in situ and real-time temperature monitoring. The thermally enhanced upconversion luminescence of the nanocrystals thermometry ensures sensitive temperature sensing in a wide temperature range, and the POF sensor exhibits stable and repeatable responses to temperature with a deviation of ±0.13 at 30 °C. Through the implementation of fluorescence POF sensors into pouch cell, the dynamic thermal state inside the LIBs is instantaneously captured without affecting the normal operations during battery cycling. This work paves the way for fluorescence POF sensors assisting in battery thermal management and evaluating the performance of battery materials for further developing LIBs.

Boron-Stabilized Anisotropic Water-in-Polymer Salt Electrolyte with an Exceptionally Low Salt Concentration by Hofmeister Effect for Aqueous Lithium-Ion Batteries

Water-based electrolytes provide safe, reliable, and cost-effective energy storage solutions; however, their application in aqueous lithium-ion batteries is hindered by low energy density and short cycling life due to the limited electrochemical stability window. While high lithium salt concentrations can mitigate some of these issues, they often lead to increased solvent viscosity and higher costs, limiting commercialization. In this study, a boron-stabilized anisotropic polyvinyl alcohol (PVA) hydrogel electrolyte, referred to as BaP, is proposed to address the challenges related to high lithium salt (LiTFSI) concentrations. Due to the Hofmeister effect, the BaP water-in-polymer electrolyte can retain a high concentration of lithium salt even when low concentrations of lithium salt are used. Briefly, the BaP promotes the salting-in phenomenon of Li ions, while the TFSI ions induce salting-out, allowing BaP to synergistically achieve high lithium salt concentrations. Due to these unique characteristics, the BaP hydrogel exhibits a wide electrochemical stability window similar to that of highly concentrated electrolytes, enabling stable operation in a LiMn2O4||Li4Ti5O12 full cell by suppressing hydrogen evolution. Moreover, the biodegradability of BaP contributes to the development of a more environmentally friendly battery system.

Dual Active Sites along with Hydrophobic Structure Modulation of Vanadium Hexacyanoferrate for Aqueous Zn-Ion Batteries

Prussian blue analogs (PBAs) have attracted significant attention for use in aqueous zinc-ion batteries (AZIBs) because of their open framework, tunability, and ease of preparation. However, PBAs are still faced with low specific capacity or poor cycling performance as cathode materials for AZIBs, which is attributed to the insufficient number of active sites and structural instability due to water molecules. In this study, vanadium with multivalent properties has been introduced to form a dual active site with Fe, providing multiple electron transfers and possessing a higher specific capacity. Meanwhile, a coprecipitation method is used to form a β-cyclodextrin (β-CD) surface layer with an excluded-volume effect and rich hydroxyl side groups on the surface of vanadium hexacyanoferrate (VOHCF). The surface layer effectively prevents the direct interaction of VOHCF with active water molecules in the electrolyte while also regulating the desolvation structure of Zn2+, enhancing the long-cycle stability of electrode materials. The prepared β-cyclodextrin-vanadium hexacyanoferrate (β-CD-VOHCF) achieves a high reversible capacity (204.1 mAh·g-1 at 0.2 A·g-1), and the capacity retention ratio improves by 65% compared with VOHCF after 3200 cycles at 5 A·g-1. This study offers new ideas to inhibit vanadium dissolution and establish a foundation for the development of VOHCF.

Acute eosinophilic pneumonia caused by an exploding mobile battery: A case report

A 42-year-old woman presented to our hospital with fever and worsening dyspnea. Eight days prior to symptom onset, she inhaled smoke from a fire caused by an exploded mobile battery. Infiltrative shadows were observed in the bilateral lung fields on chest computed tomography scan, and the eosinophil fraction of the bronchoalveolar lavage fluid was elevated to 61.2 %. Therefore, she was diagnosed with acute eosinophilic pneumonia (AEP). Although AEP can be triggered by various inhalants, including tobacco exposure, this is the first reported case of AEP caused by a mobile battery explosion.

A Hyperstable Aqueous Zinc-Ion Battery Based on Mo1.74CTz MXene

The sustainable utilization of natural resources and growing demand for various electronic devices have promoted the development of safe, stable, and rechargeable aqueous zinc-ion batteries (AZIBs). However, a stable cathode material is crucial for ZIBs in an aqueous electrolyte, since it is more difficult for divalent Zn2+ to be reversibly inserted and extracted between active materials than it is for monovalent metal ions. In this work, a tailored multi-defect MXene, Mo1.74CTz, of a complete chemical formula of Mo1.74±0.06CO0.95±0.02(OH)0.63±0.01F0.3±0.03.0.2±0.05H2Oads (Mo1.74CTz), is assembled as cathode in AZIBs. It achieved 75% capacity retention and nearly 100% Coulombic efficiency even after up to 100 000 cycles as the intrinsic structural stability and many vertical holes of the Mo1.74CTz MXene contributed to alleviating the MXene collapse under repeated charge and discharge. Meanwhile, the Mo1.74CTz-based AZIBs exhibited good performance with a specific capacity of 200 mAh g-1 at a current density of 0.2 A g-1, which greatly exceeds previous reports of pure MXene-based cathodes in AZIBs. This work will aid in finding new solutions for sustainable energy development, which will pave the way for AZIBs as an alternative to lithium-ion batteries (LIBs) in the future.

Vitrimeric electrolytes - overview and perspectives

Lithium batteries, essential for consumer electronics, transportation and the energy sector, still require further improvement in performance, safety, and sustainability. Traditonal organic solvent-based electrolytes, widely used in current systems, pose significant safety risks and restrict the development of next generation devices. Vitrimers are materials with unique physical and chemical properties, which offer a promising alternative to overcome these limitations, finally reaching processability and recyclability of solid electrolytes. Despite their potential a comprehensive overview of vitrimeric electrolytes' design and application in lithium batteries is lacking. This review article summarizes the key concepts, design principles, and notable advancements in vitrimeric electrolytes. We will also discuss the challenges still restricting the widespread adoption of vitrimeric electrolytes and explore future perspectives for leveraging vitrimeric materials in high-performance, safer, and more sustainable lithium battery technologies.

Strategies and Prospects for Engineering a Stable Zn Metal Battery: Cathode, Anode, and Electrolyte Perspectives

ConspectusZinc metal batteries (ZMBs) appear to be promising candidates to replace lithium-ion batteries owing to their higher safety and lower cost. Moreover, natural reserves of Zn are abundant, being approximately 300 times greater than those of Li. However, there are some typical issues impeding the wide application of ZMBs. Traditional inorganic cathodes exhibit an unsatisfactory cycling lifetime because of structure collapse and active materials dissolution. Apart from inorganic cathodes, organic materials are now gaining extensive attention as ZMBs cathodes because of their sustainability, high environmental friendliness, and tunable molecule structure which make them usually exhibit superior cycling life. Nevertheless, due to the inferior conductivity of organic materials, their mass loading and volumetric energy density still cannot meet our demands. In addition, the specific working mechanism of inorganic/organic cathodes also needs further investigation, necessitating the use of advanced in situ characterization technologies. Reversibility of metallic Zn anodes is also crucial in determining the overall cell performances. Like Li and Na anodes, uncontrolled dendrite growth is also an annoying problem for Zn anodes, which may penetrate the separator and cause inner short circuit. In aqueous electrolyte, highly reactive H2O molecules easily attack metallic Zn anode, leading to undesired Zn corrosion. Furthermore, during cell operation, hydrogen evolution reaction (HER) occurs, which leads to continuous consumption of electrolytes and formation of insulating byproducts on Zn anodes. Although strategies like novel Zn anode design and artificial SEI layer construction are proposed to inhibit dendrites growth and protect Zn anodes from active H2O attack, the corresponding manufacturing process remains complex. Modifying electrolyte components is relatively simple to implement and effectively stabilizes Zn anodes. However, HER cannot be completely eliminated when H2O exists in the modified electrolytes. Under such conditions, nonaqueous electrolytes appear to be a promising solution for ZMBs in the future due to their aprotic nature and high stability with the Zn anodes. However, the ionic conductivity of nonaqueous electrolytes is relatively low compared to that of aqueous electrolytes. Most of the previous reviews focus only on the individual components of ZMBs. A review of ZMBs from a higher perspective, focusing on advanced ZMBs system design, is currently lacking.In this Account, we begin with a brief overview of ZMBs, highlighting their advantages and current challenges. Subsequently, we give a summary of the development of inorganic cathodes (such as MnO2) for ZMBs. Specifically, development history and representative modification strategy of inorganic cathodes are illustrated. Following this, representative organic cathodes are discussed, along with introduction of novel modification strategies for organic cathodes. Afterward, Zn anode form design, additive selection and artificial solid electrolyte interface (SEI) layer are briefed for development of Zn anodes. Thereafter, formulation of electrolyte components is systematically discussed, highlighting potential future of nonaqueous electrolyte in ZMBs. Unlike other reviews giving very detailed information in one aspect, this Account offers an overview of current opportunities and challenges faced by ZMBs. We hope this Account can provide researchers with deeper insights into the evolution of ZMBs, encouraging them to devise effective and innovative strategies that will accelerate widespread application of ZMB technology.

Model-constrained deep learning for online fault diagnosis in Li-ion batteries over stochastic conditions

For the intricate and infrequent safety issues of batteries, online safety fault diagnosis over stochastic working conditions is indispensable. In this work, we employ deep learning methods to develop an online fault diagnosis network for lithium-ion batteries operating under unpredictable conditions. The network integrates battery model constraints and employs a framework designed to manage the evolution of stochastic systems, thereby enabling fault real-time determination. We evaluate the performance using a dataset of 18.2 million valid entries from 515 vehicles. The results demonstrate our proposed algorithm outperforms other relevant approaches, enhancing the true positive rate by over 46.5% within a false positive rate range of 0 to 0.2. Meanwhile, we identify the trigger probability for four safety fault samples, namely, electrolyte leakage, thermal runaway, internal short circuit, and excessive aging. The proposed network is adaptable to packs of varying structures, thereby reducing the cost of implementation. Our work explores the application of deep learning for real-state prediction and diagnosis of batteries, demonstrating potential improvements in battery safety and economic benefits.

Functionalized Separators Boosting Electrochemical Performances for Lithium Batteries

The growing demands for energy storage systems, electric vehicles, and portable electronics have significantly pushed forward the need for safe and reliable lithium batteries. It is essential to design functional separators with improved mechanical and electrochemical characteristics. This review covers the improved mechanical and electrochemical performances as well as the advancements made in the design of separators utilizing a variety of techniques. In terms of electrolyte wettability and adhesion of the coating materials, we provide an overview of the current status of research on coated separators, in situ modified separators, and grafting modified separators, and elaborate additional performance parameters of interest. The characteristics of inorganics coated separators, organic framework coated separators and inorganic-organic coated separators from different fabrication methods are compared. Future directions regarding new modified materials, manufacturing process, quantitative analysis of adhesion and so on are proposed toward next-generation advanced lithium batteries.

Mechanism of stable lithium plating and stripping in a metal-interlayer-inserted anode-less solid-state lithium metal battery

To reliably operate anode-less solid-state Li metal batteries, wherein precipitated Li acts as the anode, stabilizing the interface between the solid electrolyte and electrode is crucial. The interface can be controlled by a metal interlayer on the electrolyte to form a Li alloy buffer that facilitates stable Li plating/stripping, thereby mitigating the loss of physical contact and preventing short circuits. However, the mechanism governing stable Li plating/stripping in the metal interlayer without degrading battery materials remains unclear owing to an incomplete understanding of the dynamic and complex electrochemical reactions in the solid state. Through multiple operando and post-mortem analyses of the Li deposition behavior in the morphology, chemistry and microstructure, a close correlation is found between the Li-metal alloying process with the microstructural evolution and electrochemical performance when Ag, Au, Zn, and Cu interlayers were adopted on the garnet-type solid electrolyte Li6.5La3Zr1.5Ta0.5O12. The Ag interlayer improved the interfacial stability enabled by Ag-dissolved Li, which inhibited dendritic growth, passing through the phase-separated Li-Ag alloy microstructure, while the other metals did not because of the Li plating at the Li-metal alloy/solid electrolyte interface. This work provides fundamental guidance for material selection and interface design, advancing the development of anode-less solid-state batteries.

A Knowledge-Data Dual-Driven Framework for Predicting the Molecular Properties of Rechargeable Battery Electrolytes

Developing rechargeable batteries that operate within a wide temperature range and possess high safety has become necessary with increasing demands. Rapid and accurate assessment of the melting points (MPs), boiling points (BPs), and flash points (FPs) of electrolyte molecules is essential for expediting battery development. Herein, we introduce Knowledge-based electrolyte Property prediction Integration (KPI), a knowledge-data dual-driven framework for molecular property prediction of electrolytes. Initially, the KPI collects molecular structures and properties, and then automatically organizes them into structured datasets. Subsequently, interpretable machine learning further explores the structure-property relationships of molecules from a microscopic perspective. Finally, by embedding the discovered knowledge into property prediction models, the KPI achieved very low mean absolute errors of 10.4, 4.6, and 4.8 K for MP, BP, and FP predictions, respectively. The KPI reached state-of-the-art results in 18 out of 20 datasets. Utilizing molecular neighbor search and high-throughput screening, 15 and 14 promising molecules, with and without Chemical Abstracts Service Registry Number, respectively, were predicted for wide-temperature-range and high-safety batteries. The KPI not only accurately predicts molecular properties and deepens the understanding of structure-property relationships but also serves as an efficient framework for integrating artificial intelligence and domain knowledge.

Crystal structure regulation of trititanium pentoxide for advanced zero-strain lithium storage anode

Significant advancements have been made in electric vehicles and consumer devices. However, lithium-ion batteries with commercial graphite anodes still face challenges owing to their sluggish lithium-ion kinetics, low lithiation potential, and limited cycle stability. Consequently, there is a considerable research interest in developing new anode materials with rich resources, "zero-strain" characteristics for long-term cycling, and outstanding electrochemical properties. In this study, we thoroughly examine the relationship between the structure and electrochemical characteristics of λ and β phases of titanium pentoxides (Ti3O5). The findings indicate that the β phase of Ti3O5 exhibits a overall electrochemical performance compared to the λ phase. Moreover, β-Ti3O5 electrodes deliver a low, yet safe average operating potential of 0.82 V versus Li/Li+ and a reversible specific capacity of 181.9 mA h/g at 0.1 A/g, thereby significantly outperforming λ-Ti3O5 electrodes, with a value of only 55.7 mA h/g. The performance difference can be primarily attributed to the changes in the crystal structure, with the β phase exhibiting a lower energy barrier for lithium-ion diffusion than the λ-phase. Moreover, the β-Ti3O5 electrodes exhibit an good rate performance (capacity retention of 49.5 % at 10 A/g) and good cycling stability (absence of capacity degradation after 2000 cycles at 1.0 A g-1). These advantages suggest that β-Ti3O5 is a promising anode material for reliable, rapid-charging, and secure lithium-ion storage.

Challenges and opportunities for high-quality battery production at scale

As the world electrifies, global battery production is expected to surge. However, batteries are both difficult to produce at the gigawatt-hour scale and sensitive to minor manufacturing variation. As a result, the battery industry has already experienced both highly-visible safety incidents and under-the-radar reliability issues-a trend that will only worsen if left unaddressed. Here we highlight both the challenges and opportunities to enable battery quality at scale. We first describe the interplay between various battery failure modes and their numerous root causes. We then discuss how to manage and improve battery quality during production. We hope our perspective brings greater visibility to the battery quality challenge to enable safe global electrification.

Polysilaketals: High-Performance Polyether-Based Electrolytes with Tunable Disubstituted Silane Linkers

Polymer electrolytes exhibit higher energy density and improved safety in lithium-ion batteries relative to traditionally used liquid electrolytes but are currently limited by their lower electrochemical performance. Aiming to access polymer electrolytes with competitive electrochemical properties, we developed the anionic ring-opening polymerization (AROP) of cyclic silaketals to synthesize amorphous silicon-containing polyether-based electrolytes with varying substituent bulk of the general formula [OSi(R)2(CH2CH2O)2]n (R=alkyl, phenyl). As opposed to previously reported uncontrolled polycondensation routes toward low molecular weight polysilaketals, AROP allows access to targeted molecular weights above the entanglement threshold of the polymers. The polysilaketal with the lowest steric bulk (P(OSiMe,Me-2EO)) exceeds the conductivity of poly(ethylene oxide) (PEO), a leading polymer electrolyte. To the best of our knowledge, this is the first solid polymer electrolyte to achieve this benchmark. Steric bulk in polysilaketals was found to impart stability and two bulkier polysilaketals, P(OSiEt,Et-2EO) and P(OSiMe,Ph-2EO), exhibited higher current fractions than PEO over a wide range of salt loadings. Moreover, the efficacy of P(OSiEt,Et-2EO) was competitive with that of PEO. Taken together, the tunable and competitive electrochemical properties of polysilaketals validate the systematic incorporation of silyl groups as a strategy to access high performance polymer electrolytes.

Designing Nonflammable Liquid Electrolytes for Safe Li-Ion Batteries

Li-ion batteries are essential technologies for electronic products in the daily life. However, serious fire safety concerns that are closely associated with the flammable liquid electrolyte remains a key challenge. Tremendous effort has been devoted to designing nonflammable liquid electrolytes. It is critical to gain comprehensive insights into nonflammability design and inspire more efficient approaches for building safer Li-ion batteries. This review presents current mechanistic understanding of safety issues and discusses state-of-the-art nonflammable liquid electrolytes design for Li-ion batteries based on molecule, solvation, and battery compatibility level. Various safety test methods are discussed for reliable safety risk evaluation. Finally, the challenges and perspectives of the nonflammability design for Li-ion electrolytes are summarized.

Infrared nanosensors of piconewton to micronewton forces

Mechanical force is an essential feature for many physical and biological processes1-7, and remote measurement of mechanical signals with high sensitivity and spatial resolution is needed for diverse applications, including robotics8, biophysics9,10, energy storage11 and medicine12,13. Nanoscale luminescent force sensors excel at measuring piconewton forces, whereas larger sensors have proven powerful in probing micronewton forces14-16. However, large gaps remain in the force magnitudes that can be probed remotely from subsurface or interfacial sites, and no individual, non-invasive sensor is capable of measuring over the large dynamic range needed to understand many systems14,17. Here we demonstrate Tm3+-doped avalanching-nanoparticle18 force sensors that can be addressed remotely by deeply penetrating near-infrared light and can detect piconewton to micronewton forces with a dynamic range spanning more than four orders of magnitude. Using atomic force microscopy coupled with single-nanoparticle optical spectroscopy, we characterize the mechanical sensitivity of the photon-avalanching process and reveal its exceptional force responsiveness. By manipulating the Tm3+ concentrations and energy transfer within the nanosensors, we demonstrate different optical force-sensing modalities, including mechanobrightening and mechanochromism. The adaptability of these nanoscale optical force sensors, along with their multiscale-sensing capability, enable operation in the dynamic and versatile environments present in real-world, complex structures spanning biological organisms to nanoelectromechanical systems.

Fish-inspired dynamic charging for ultrafast self-protective solar-thermal energy storage

Solar-thermal energy storage (STES) within solid-liquid phase change materials (PCMs) has emerged as an attractive solution to overcome intermittency of renewable energy. However, current storage systems usually suffer from slow charging rates, sacrificed storage capacity, and overheating tendency. Inspired by the thermoregulation behavior of Cyprinid fish, here, we present a quick-responsive, ultrafast, large-capacity, overheating-protective STES strategy. We fabricate a liquid-infused solar-absorbing foam charger that can rapidly advance the receding solid-liquid charging interface to efficiently store solar-thermal energy as latent heat and spontaneously float upward to cease the charging process upon overheating. This bioinspired dynamic charging is adaptable to a variety of PCMs, unlocking the potential for safe and efficient utilization of renewable thermal energy.

Nanoporous Aramid Nanofiber Separators with High Modulus and Thermal Stability for Safe Lithium-Ion Batteries

Developing high-safety separators is a promising strategy to prevent thermal runaway in lithium-ion batteries (LIBs), which stems from the low melting temperatures and inadequate modulus of commercial polyolefin separators. However, achieving high modulus and thermal stability, along with uniform nanopores in these separators, poses significant challenges. Herein, the study presents ultrathin nanoporous aramid nanofiber (ANF) separators with high modulus and excellent thermal stability, enhancing the safety of LIBs. These separators are produced using a microfluidic-based continuous printing strategy, where the flow thickness can be meticulously controlled at the micrometer scale. This method allows for the continuous fabrication of nanoporous ANF separators with thicknesses ranging from 1.6 ± 0.1 µm to 2.7 ± 0.1 µm. Thanks to the double-side solvent diffusion, the separators exhibit controllably uniform pore sizes with a narrow distribution, spanning from 40 ± 5 nm to 105 ± 9 nm, and a high modulus of 3.3 ± 0.5 GPa. These nanoporous ANF separators effectively inhibit lithium dendrite formation, resulting in a high-capacity retention rate for the LIBs (80% after 240 cycles). Most notably, their robust structural and mechanical stability at elevated temperatures significantly enhances LIB safety under transient thermal abuse conditions, thus addressing critical safety concerns associated with LIBs.

Ecofriendly, Highly Selective Lithium Extraction by Redox-Mediated Electrodialysis

The rapid proliferation of lithium battery applications has underscored the critical role of lithium supply in the transition to industrial electrification. Existing lithium production methods encounter significant challenges in efficiency, scalability, environmental impact, and cost. The integration of redox-mediated electrodialysis with a dense ceramic Li6/16Sr7/16Ta3/4Hf1/4O3 perovskite membrane, distinguished by its unique lattice structure allowing only lithium-ion exchange and transport, enables efficient, highly lithium-selective extraction directly from a diversity of resources including seawater and various brines. This approach offers continuous operation capability, can utilize renewable power, and has notable advantages, including chemical-free operation and little waste generation. Overall, this innovative solution presents a one-step, ecofriendly, highly selective lithium extraction method.

Revealing how internal sensors in a smart battery impact the local graphite lithiation mechanism

Smart batteries, i.e., equipped with internal and external sensors, are emerging as promising solutions to enhance battery state of health and optimize operating conditions. However, for accurate correlations between the evolution of the cell parameters (e.g., temperature, strain) and physicochemical degradation mechanisms, it is crucial to know the reliability of sensors. To address this question, we perform a synchrotron operando X-ray diffraction experiment to investigate the local and global impact of the presence of internal sensors on a commercial prismatic Li-ion battery cell at various (dis)charge rates. We find that, while the overall electrochemical performance is unaffected, the sensors have a substantial impact on the local graphite lithiation kinetics, especially at high (dis)charge rates. These results show the importance of controlling local deformations induced by internal sensors and tailoring the dimensions of these sensors to obtain reliable battery performance indicators and optimize smart batteries.

Electrolyte Design Strategies for Aqueous Sodium-Ion Batteries: Progress and Prospects

Sodium-ion batteries (SIBs) have emerged as one of today's most attractive battery technologies due to the scarcity of lithium resources. Aqueous sodium-ion batteries (ASIBs) have been extensively researched for their security, cost-effectiveness, and eco-friendly properties. However, aqueous electrolytes are extremely limited in practical applications because of the narrow electrochemical stability window (ESW) with extremely poor low-temperature performance. The first part of this review is an in-depth discussion of the reasons for the inferior performance of aqueous electrolytes. Next, research progress in extending the electrochemical stabilization window and improving low-temperature performance using various methods such as "water-in-salt", eutectic, and additive-modified electrolytes is highlighted. Considering the shortcomings of existing solid electrolyte interphase (SEI) theory, recent research progress on the solvation behavior of electrolytes is summarized based on the solvation theory, which elucidates the correlation between the solvation structure and the electrochemical performance, and three methods to upgrade the electrochemical performance by modulating the solvation behavior are introduced in detail. Finally, common design ideas for high-temperature resistant aqueous electrolytes that are hoped to help future aqueous batteries with wide temperature ranges are summarized.

Imaging in-operando LiCoO2 nanocrystallites with Bragg coherent X-ray diffraction

Although the LiCoO2 (LCO) cathode material has been widely used in commercial lithium ion batteries (LIB) and shows high stability, LIB's improvements have several challenges that still need to be overcome. In this paper, we have studied the in-operando structural properties of LCO within battery cells using Bragg Coherent X-ray Diffraction Imaging to identify ways to optimise the LCO batteries' cycling. We have successfully reconstructed the X-ray scattering phase variation (a fingerprint of atomic displacement) within a  ≈ (1.6 × 1.4 × 1.3) μm3 LCO nanocrystal across a charge/discharge cycle. Reconstructions indicate strained domains forming, expanding, and fragmenting near the surface of the nanocrystal during charging, with a determined maximum relative lattice displacements of 0.467 Å. While discharging, all domains replicate in reverse the effects observed from the charging states, but with a lower maximum relative lattice displacements of 0.226 Å. These findings show the inefficiency-increasing domain dynamics within LCO lattices during cycling.

Advanced electrolytes for high-performance aqueous zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) have garnered significant attention in the realm of large-scale and sustainable energy storage, primarily owing to their high safety, low cost, and eco-friendliness. Aqueous electrolytes, serving as an indispensable constituent, exert a direct influence on the electrochemical performance and longevity of AZIBs. Nonetheless, conventional aqueous electrolytes often encounter formidable challenges in AZIB applications, such as the limited electrochemical stability window and the zinc dendrite growth. In response to these hurdles, a series of advanced aqueous electrolytes have been proposed, such as "water-in-salt" electrolytes, aqueous eutectic electrolytes, molecular crowding electrolytes, and hydrogel electrolytes. This comprehensive review commences by presenting an in-depth overview of the fundamental compositions, principles, and distinctive characteristics of various advanced aqueous electrolytes for AZIBs. Subsequently, we systematically scrutinizes the recent research progress achieved with these advanced aqueous electrolytes. Furthermore, we summarizes the challenges and bottlenecks associated with these advanced aqueous electrolytes, along with offering recommendations. Based on the optimization of advanced aqueous electrolytes, this review outlines future directions and potential strategies for the development of high-performance AZIBs. This review is anticipated to provide valuable insights into the development of advanced electrolyte systems for the next generation of stable and sustainable multi-valent secondary batteries.

Redox-Active High-Performance Polyimides as Versatile Electrode Materials for Organic Lithium- and Sodium-Ion Batteries

Organic electrode materials for rechargeable batteries show great promise for improving the storage capacity, reducing production costs, and minimizing environmental impact toward sustainability. In this study, we report a series of newly synthesized arylamine-based polyimides, TPPA-PIs, with three different bridge functionalizations on the imide rings and isomeric constituents that can work as versatile battery electrodes. As a lithium-ion battery cathode, a maximum energy density of 248 Wh kg-1 with high voltage operation up to 4.0 V can be achieved. As a lithium-ion battery anode, the TPPA-PIs showed a reversible storage capacity of 806 mA h g-1 at 100 mA g-1 current density with good rate capability up to a current density of 2000 mA g-1. Moreover, when applied as sodium-ion battery anodes, TPPA-PIs delivered an optimum specific capacity of up to 218 mA h g-1 after 50 cycles at a 50 mA g-1 current density and revealed a long cycling stability up to 1000 cycles under a high current density of 1000 mA g-1. More importantly, these electrochemical performances of TPPA-PIs are among the best compared with other reported polymer-based electrodes. The mechanistic studies show that both bridge functionalization on the imide units and isomerism impact the electrochemical performance by regulating their intrinsic properties such as charge storage behavior, ion diffusivity, and activation energy. We believe that such a detailed study of the structural design to electrochemical performance of these polymeric electrodes will offer insights into materials development and optimization for next-generation multifunctional energy storage devices in a wide range of applications.

Photo-Crosslinked Polyurethane-Containing Gel Polymer Electrolytes via Free-Radical Polymerization Method

Using a novel technique, crosslinked gel polymer electrolytes (GPEs) designed for lithium-ion battery applications have been created. To form the photo crosslink via free-radical polymerization, a mixture of polyurethane acrylate (PUA), polyurethane methacrylate (PUMA), vinyl phosphonic acid (VPA), and bis[2-(methacryloyloxy)ethyl] phosphate (BMEP) was exposed to ultraviolet (UV) radiation during the fabrication process. The unique crosslinked configuration of the membrane increased its stability and made it suitable for use with liquid electrolytes. The resulting GPE has a much higher ionic conductivity (1.83 × 10-3 S cm-1) than the commercially available Celgrad2500 separator. A crosslinked structure formed by the hydrophilic properties of the PUA-PUMA blend and the higher phosphate content from BMEP reduced the leakage of the electrolyte solution while at the same time providing a greater capacity for liquid retention, significantly improving the mechanical and thermal stability of the membrane. GPP2 shows electrochemical stability up to 3.78 V. The coin cell that was assembled with a LiFePO4 cathode had remarkable cycling characteristics and generated a high reversible capacity of 149 mA h g-1 at 0.1 C. It also managed to maintain a consistent Coulombic efficiency of almost 100%. Furthermore, 91.5% of the original discharge capacity was maintained. However, the improved ionic conductivity, superior electrochemical performance, and high safety of GPEs hold great promise for the development of flexible energy storage systems in the future.

Effect of a Polypropylene Separator with a Thin Electrospun Ceramic/Polymer Coating on the Thermal and Electrochemical Properties of Lithium-Ion Batteries

Lithium-ion batteries (LIBs) are well known for their energy efficiency and environmental benefits. However, increasing their energy density compromises their safety. This study introduces a novel ceramic-coated separator to enhance the performance and safety of LIBs. Electrospinning was used to apply a coating consisting of an alumina (Al2O3) ceramic and polyacrylic acid (PAA) binder to a polypropylene (PP) separator to significantly improve the mechanical properties of the PP separator and, ultimately, the electrochemical properties of the battery cell. Tests with 2032-coin cells showed that the efficiency of cells containing separators coated with 0.5 g PAA/Al2O3 was approximately 10.2% higher at high current rates (C-rates) compared to cells with the bare PP separator. Open circuit voltage (OCV) tests revealed superior thermal safety, with bare PP separators maintaining stability for 453 s, whereas the cells equipped with PP separators coated with 4 g PAA/Al2O3 remained stable for 937 s. The elongation increased from 88.3% (bare PP separator) to 129.1% (PP separator coated with 4 g PAA/Al2O3), and thermal shrinkage decreased from 58.2% to 34.9%. These findings suggest that ceramic/PAA-coated separators significantly contribute to enhancing the thermal safety and capacity retention of high-energy-density LIBs.

Interfacial chemistry in multivalent aqueous batteries: fundamentals, challenges, and advances

As one of the most promising electrochemical energy storage systems, aqueous batteries are attracting great interest due to their advantages of high safety, high sustainability, and low costs when compared with commercial lithium-ion batteries, showing great promise for grid-scale energy storage. This invited tutorial review aims to provide universal design principles to address the critical challenges at the electrode-electrolyte interfaces faced by various multivalent aqueous battery systems. Specifically, deposition regulation, ion flux homogenization, and solvation chemistry modulation are proposed as the key principles to tune the inter-component interactions in aqueous batteries, with corresponding interfacial design strategies and their underlying working mechanisms illustrated. In the end, we present a critical analysis on the remaining obstacles necessitated to overcome for the use of aqueous batteries under different practical conditions and provide future prospects towards further advancement of sustainable aqueous energy storage systems with high energy and long durability.

Noncombustible gel polymer electrolyte inspired by bio-radicalchemistry for high voltage and high safety Ni-rich lithium batteries

For high energy density lithium-ion batteries (LIBs) with nickel-rich ternary cathodes, the chemical degradation of electrolytes caused by free radical reactions and the hazards of thermal runaway have always been significant challenges. Inspired by the free radical scavenging of living organisms and multiphase synergistic flame retardant mechanism, we innovatively designed and prepared a multifunctional flame retardant HCCP-TMP that combines flame retardancy and free radical scavenging by combining hindered amine and cyclophosphazene. Only 1 wt% HCCP-TMP can make the polyacrylate-based gel polymer electrolyte (GPE) incombustible. Moreover, the equipped NCM811//Graphite pouch cells don't exhibit combustion behavior after thermal runaway and can resist mechanical abuse. Based on the above noncombustible GPE, the NCM811//Li battery exhibits capacity retention rate of 82.2 % after 100 cycles at a current density of 2 C and in the voltage range of 3.0-4.7 V, exhibiting excellent cyclability under high voltage. This simple molecular design simultaneously improves the fire safety and high voltage stability, demonstrating enormous application potential in the field of advanced LIBs with high safety and high energy density.

Coating Robust Layers on Ni-Rich Cathode Active Materials while Suppressing Cation Mixing for All-Solid-State Lithium-Ion Batteries

This study focused on addressing the challenges associated with the incompatibility between sulfide solid electrolytes and Ni-rich cathode active materials (CAMs) in all-solid-state lithium-ion batteries. To resolve these issues, protective layers have been explored for Ni-rich materials. Lithium lanthanum titanate (LLTO), a perovskite-type material, is recognized for its excellent chemical stability and ionic conductivity, which render it a potential protective layer in CAMs. However, traditional methods of achieving the perovskite structure involve temperatures exceeding 700 °C, resulting in challenges such as LLTO agglomeration, secondary phase formation between LLTO and CAM, and cation mixing within the CAM. In this study, a rapid technique known as flash-light sintering (FLS) was employed to fabricate a uniform and pure perovskite protective layer without inducing cation mixing within the CAM. The LLTO-coated LiNi0.8Co0.1Mn0.1O2 (NCM811) with FLS treatment demonstrated minimal cation mixing and formed a fully covered dense layer. This resulted in a high initial capacity and effectively addressed the incompatibility issues between the sulfide electrolytes and CAM. The rapid FLS method not only streamlines the fabrication of LLTO-coated NCM811 but also provides opportunities for its broader application to materials that were previously deemed impractical because of high sintering temperatures.

A novel causative factor of injury: Severe burns related to fires and explosions of lithium-ion batteries of electric motorcycles

Severe burns related to fires and explosions of lithium-ion batteries of electric motorcycles have not been reported to date. We retrospectively studied 419 patients admitted to our burn intensive care unit from January 2016 to December 2021. Of these 419 patients, 26 (22 male, 4 female; median age, 42 years) had burns related to lithium-ion battery fires and explosions, and all of their injury characteristics were similar to those of traditional flame burns. Lithium-ion battery-related burns were the eighth most common cause of burn injuries among all hospitalized patients. The 26 patients comprised 10 unemployed and 16 employed individuals. Twenty-three patients were injured at home during the battery charging process, and three were injured outdoors (one by a fire while the electric motorcycle was stationary and the others two by a fire while riding the motorcycle). The burn sites were distributed over the whole body; the burn area ranged from 10 % to 100 % of the total body surface area, and the burn depth ranged from superficial second-degree burns to third-degree burns. Twenty-three patients had inhalation injuries, and ten underwent prophylactic tracheostomy and intubation. Multiple operations were required for wound repair. Although convenient, lithium-ion electric motorcycles can also cause severe burns. To prevent these injuries, we must increase public safety awareness and education, develop new battery energy storage systems and battery management systems, and ensure the safety of batteries. Consumers should be aware of the potential dangers of lithium-ion batteries and comply with related security measures.

Lithium fluorosulfonate-induced low-resistance interphase boosting low-temperature performance of commercial graphite/LiFePO4 pouch batteries

The performance of Li-ion batteries (LIBs) at sub-ambient temperatures is limited by the resistive interphases due to electrolyte decomposition, particularly on the anode surface. In this study, lithium fluorosulfonate (LFS) was added to commercial electrolytes to enhance the low-temperature electrochemical performance of LiFePO4 (LFP)/graphite (Gr) pouch cells. The addition of LFS significantly reduced the charge transfer resistance of the anode, substantially extending the cycle life and discharge capacity of commercial LFP/Gr pouch cells at -10 and -30 °C. Compared with the capacity retention rate of the baseline electrolyte at -10 °C (80 % after 25cycles), the capacity retention rate of the LFS electrolyte after 100 cycles under 0.5 C/0.5 C was retained at 94 %. Further mechanistic studies showed that the LFS additive induced the formation of a solid electrolyte interphase (SEI) film comprising inorganic-rich LiF, Li2SO4, and additional organic fluorides and sulfides to maintain good stability at the Gr/electrolyte interface during low-temperature operation. LFS suppressed electrolyte decomposition by forming a robust and low-resistance SEI film on the anode. These results demonstrate that LFS is a promising electrolyte additive for low-temperature LFP/Gr pouch cells.

Localized High-Concentration Sulfone Electrolytes with High-Voltage Stability and Flame Retardancy for Ni-Rich Lithium Metal Batteries

The localized high-concentration electrolyte (LHCE) propels the advanced high-voltage battery system. Sulfone-based LHCE is a transformative direction compatible with high energy density and high safety. In this work, the application of lithium bis(trifluoromethanesulphonyl)imide and lithium bis(fluorosulfonyl)imide (LiFSI) in the LHCE system constructed from sulfolane and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) is investigated. The addition of diluent causes an increase of contact ion pairs and ionic aggregates in the solvation cluster and an acceptable quantity of free solvent molecules. A small amount of LiFSI as an additive can synergistically decompose with TTE on the cathode and participate in the construction of both electrode interfaces. The designed electrolyte helps the Ni-rich system to cycle firmly at a high voltage of 4.5 V. Even with high mass load and lean electrolyte, it can keep a reversible specific capacity of 91.5% after 50 cycles. The constructed sulfone-based electrolyte system exhibits excellent thermal stability far beyond the commercial electrolytes. Further exploration of in-situ gelation has led to a quick conversion of the designed liquid electrolyte to the gel state, accompanied by preserved stability, which provides a direction for the synergistic development of LHCE with gel electrolytes.

Oxygen Substitution to Enhance Chemo-Mechanical Stability at the Cathode-Sulfide Electrolyte Interface in All-Solid-State Batteries

The high interface resistance at the cathode-sulfide electrolyte interface is still a crucial drawback in an all-solid-state battery, unlike the initial expectation that the all-solid-state interface would enhance electrochemical stability by reducing side reactions at the interface. In this study, we examined the fundamental mechanism of unexpected reactions at the interface of LiNi0.8Co0.1Mn0.1O2 (NCM811) and argyrodite (Li6PS5Br0.5Cl0.5, LPSBC) sulfide solid electrolytes based on the combined method of multiscale simulations and electrochemical experiments. The high interface resistance originates from the formation of a passivating layer at the interface combined with irregular atomic and electronic structures, Li depletion, mutual element exchange, and mechanical contact loss between the oxide cathode and sulfide solid electrolyte. We also confirmed that these side reactions were suppressed by O substitutions to sulfide solid electrolyte (LPSOBC), and then the chemo-mechanical stability of the all-solid battery was enhanced by alleviating the side reactions at the interface. This study provides rational insights into the design of an interface for all-solid-state batteries.

Integrated Interfacial Modulation Strategy: Trace Sodium Hydroxyethyl Sulfonate Additive for Extended-Life Zn Anode Based on Anion Adsorption and Electrostatic Shield

Aqueous zinc-ion batteries (AZIBs) are poised to play a pivotal part in meeting the growing demands for energy storage and powering portable electronics for their superior security, affordability, and environmentally friendly characteristics. However, the detrimental side reactions occurring at the zinc anode and the dendrite caused by uneven zinc plating/stripping have greatly compromised the cycling life of AZIBs, thereby impeding their practical prospects. In this study, the interfacial comodulation strategy was employed by combining the "electrostatic shielding" effect of cations with the characteristic adsorption of anions. Two molar ZnSO4 served as the matrix, and sodium hydroxyethyl sulfonate (SHES) was selected as a low-cost, nontoxic additive. Experimental results confirm that SHES and zinc anode exhibit robust interactions that lead to the formation of an electrostatic shield and a dynamic adsorption layer at the interface, thereby suppressing hydrogen evolution and corrosion. The combined "electrostatic shielding" effect of sodium ions and the robust characteristic adsorption of hydroxyethyl sulfonate anions serve to guide the directed three-dimensional (3D) diffusion of Zn2+, facilitating rapid, stable, and uniform deposition of zinc. Due to these effects, incorporating 0.2 M SHES as an additive extends the cycle life beyond 3600 h and enables a highly reversible process of deposition and stripping in symmetric cells. Additionally, the Zn-Cu half-cell exhibits reliable cycling for over 1400 cycles, achieving an average Coulombic efficiency of 99.6%. Moreover, the introduction of this additive substantially enhances the performance of Zn-MnO2 and Zn-NH4V4O10 full cells. This study demonstrates the practical feasibility of achieving anodes with high reversibility in AZIBs through the implementation of a strategy that involves anion adsorption at the interface, which holds paramount significance for the practical application of AZIBs.

Mitigating Gas Evolution in Electron Beam-Induced Gel Polymer Electrolytes Through Bi-Functional Cross-Linkable Additives

The current high-capacity lithium-ion batteries (LIBs), reliant on flammable liquid electrolytes (LEs) and nickel-rich cathodes, are plagued by safety hazards, especially the risk of hazardous gas release stemming from internal side reactions. To address these safety concerns, an electron beam (E-beam)-induced gel polymer electrolyte (E-Gel) is introduced, employing dipentaerythritol hexaacrylate (DPH) as a bi-functional cross-linkable additive (CIA). The dual roles of DPH are exploited through a strategically designed E-beam irradiation process. Applying E-beam irradiation on the pre-cycled cells allows DPH to function as an additive during the initial cycle, establishing a protective layer on the surface of the anode and cathode and as a cross-linker during the E-beam irradiation step, forming a polymer framework. The prepared E-Gel with CIA has superior interfacial compatibility, facilitating lithium-ion diffusion at the electrode/E-Gel interface. The electrochemical assessment of 1.2 Ah pouch cells demonstrates that E-Gel substantially reduces gas release by 2.5 times compared to commercial LEs during the initial formation stage and ensures superior reversible capacity retention even after prolonged cycling at 55 °C. The research underscores the synergy of bifunctional CIA with E-beam technology, paving the way for large-scale production of safe, high-capacity, and commercially viable LIBs.

Electrochemical Failure Mechanism of δ-MnO2 in Zinc Ion Batteries Induced by Irreversible Layered to Spinel Phase Transition

Phase transitions of Mn-based cathode materials associated with the charge and discharge process play a crucial role on the rate capability and cycle life of zinc ion batteries. Herein, a microscopic electrochemical failure mechanism of Zn-MnO2 batteries during the phase transitions from δ-MnO2 to λ-ZnMn2O4 is presented via systematic first-principle investigation. The initial insertion of Zn2+ intensifies the rearrangement of Mn. This is completed by the electrostatic repulsion and co-migration between guest and host ions, leading to the formation of λ-ZnMn2O4. The Mn relocation barrier for the λ-ZnMn2O4 formation path with 1.09 eV is significantly lower than the δ-MnO2 re-formation path with 2.14 eV, indicating the irreversibility of the layered-to-spinel transition. Together with the phase transition, the rearrangement of Mn elevates the Zn2+ migration barrier from 0.31 to 2.28 eV, resulting in poor rate performance. With the increase of charge-discharge cycles, irreversible and inactive λ-ZnMn2O4 products accumulate on the electrode, causing continuous capacity decay of the Zn-MnO2 battery.

Earth-Abundant Kaolinite Nanoplatelet Gel Electrolytes for Solid-State Lithium Metal Batteries

Lithium-ion batteries are the leading energy storage technology for portable electronics and vehicle electrification. However, demands for enhanced energy density, safety, and scalability necessitate solid-state alternatives to traditional liquid electrolytes. Moreover, the rapidly increasing utilization of lithium-ion batteries further requires that next-generation electrolytes are derived from earth-abundant raw materials in order to minimize supply chain and environmental concerns. Toward these ends, clay-based nanocomposite electrolytes hold significant promise since they utilize earth-abundant materials that possess superlative mechanical, thermal, and electrochemical stability, which suggests their compatibility with energy-dense lithium metal anodes. Despite these advantages, nanocomposite electrolytes rarely employ kaolinite, the most abundant variety of clay, due to strong interlayer interactions that have historically precluded efficient exfoliation of kaolinite. Overcoming this limitation, here we demonstrate a scalable liquid-phase exfoliation process that produces kaolinite nanoplatelets (KNPs) with high gravimetric surface area, thus enabling the formation of mechanically robust nanocomposites. In particular, KNPs are combined with a succinonitrile (SN) liquid electrolyte to form a nanocomposite gel electrolyte with high room-temperature ionic conductivity (1 mS cm-1), stiff storage modulus (>10 MPa), wide electrochemical stability window (4.5 V vs Li/Li+), and excellent thermal stability (>100 °C). The resulting KNP-SN nanocomposite gel electrolyte is shown to be suitable for high-rate rechargeable lithium metal batteries that employ high-voltage LiNi0.8Co0.15Al0.05O2 (NCA) cathodes. While the primary focus here is on solid-state batteries, our strategy for kaolinite liquid-phase exfoliation can serve as a scalable manufacturing platform for a wide variety of other kaolinite-based nanocomposite applications.

N-Containing Na2VTi(PO4)3/C for Aqueous Sodium-Ion Batteries

Phosphates featuring a 3D framework offer a promising alternative to aqueous sodium-ion batteries, known for their safety, cost-effectiveness, scalability, high power density, and tolerance to mishandling. Nevertheless, they often suffer from poor reversible capacity stemming from limited redox couples. Herein, N-containing Na2VTi(PO4)3 is synthesized for aqueous sodium-ion storage through multi-electron redox reactions. It demonstrates a capacity of 155.2 mAh g-1 at 1 A g-1 (≈ 5.3 C) and delivers an ultrahigh specific energy of 55.9 Wh kg-1 in a symmetric aqueous sodium-ion battery. The results from in situ X-ray diffraction analysis, ex situ X-ray photoelectron spectroscopy analysis, and first-principle calculations provide insights into the local chemical environment of sodium ions, the mechanisms underlying capacity decay during cycling, and the dynamics of ion and electron transfer at various states of charge. This understanding will contribute to the advancement of electrode materials for aqueous sodium-ion batteries.

Superspreading-Based Fabrication of Thermostable Nanoporous Polyimide Membranes for High Safety Separators of Lithium-Ion Batteries

The development of thermally stable separators is a promising approach to address the safety issues of lithium-ion batteries (LIBs) owing to the serious shrinkage of commercial polyolefin separators at elevated temperatures. However, achieving controlled nanopores with a uniform size distribution in thermostable polymeric separators and high electrochemical performance is still a great challenge. In this study, nanoporous polyimide (PI) membranes with excellent thermal stability as high-safety separators is developed for LIBs using a superspreading strategy. The superspreading of polyamic acid solutions enables the generation of thin and uniform liquid layers, facilitating the formation of thin PI membranes with controllable and uniform nanopores with narrow size distribution ranging from 121 ± 5 nm to 86 ± 6 nm. Such nanoporous PI membranes display excellent structural stability at elevated temperatures up to 300 °C for at least 1 h. LIBs assembled with nanoporous PI membranes as separators show high specific capacity and Coulombic efficiency and can work normally after transient treatment at a high temperature (150 °C for 20 min) and high ambient temperature, indicating their promising application as high-safety separators for rechargeable batteries.

Phase Evolution of Multi-Metal Dichalcogenides With Conversion-Alloying Hybrid Mechanism for Superior Lithium Storage

Traditional lithium-ion battery (LIB) anodes, whether intercalation-type like graphite or alloying-type like silicon, employing a single lithium storage mechanism, are often limited by modest capacity or substantial volume changes. Here, the kesterite multi-metal dichalcogenide (CZTSSe) is introduced as an anode material that harnesses a conversion-alloying hybrid lithium storage mechanism. Results unveil that during the charge-discharge processes, the CZTSSe undergoes a comprehensive phase evolution, transitioning from kesterite structure to multiple dominant phases of sulfides, selenides, metals, and alloys. The involvement of multi-components facilitates electron transport and mitigates swelling stress; meanwhile, it results in formation of abundant defects and heterojunctions, allowing for increased lithium storage active sites and reduced lithium diffusion barrier. The CZTSSe delivers a high specific capacity of up to 2266 mA h g-1 at 0.1 A g-1; while, maintaining a stable output of 116 mA h g-1 after 10 000 cycles at 20 A g-1. It also demonstrates remarkable low-temperature performance, retaining 987 mA h g-1 even after 600 cycles at -40 °C. When employed in full cells, a high specific energy of 562 Wh kg-1 is achieved, rivalling many state-of-the-art LIBs. This research offers valuable insights into the design of LIB electrodes leveraging multiple lithium storage mechanisms.