Behavior of Solid Electrolyte in Li-Polymer Battery with NMC Cathode via in-Situ Scanning Electron Microscopy

Constructing Nano-Interlayer Inhibiting Interfacial Degradation toward High-Voltage PEO-Based All-Solid-State Lithium Batteries

The interfacial instability between PEO-based solid electrolyte (SPE) and high-voltage cathode materials inhibits the longevity of high-energy-density all-solid-state polymer lithium metal batteries (ASSPLBs). Herein, for the first time it is demonstrated, that contact loss caused by gas generation from interfacial side reactions between the high-voltage cathode and solid polymer electrolyte (SPE) can also arise in ASSPLBs. To alleviate the interfacial side reactions, a LiNb0.6Ti0.5O3 (LNTO) layer is well coated on LiNi0.83Co0.07Mn0.1O2 (NCM83), denoted as (CNCM83). The LNTO layer with low electronic conductivity reduces the decomposition drive force of SPE. Furthermore, Ti and Nb in the LNTO layer spontaneously migrate inside the NCM83 surface to form a strong Ti/Nb─O bond, stalling oxygen evolution in high-voltage cathodes. The interfacial degradation phenomena, including SPE decomposition, detrimental phase transition and intragranular cracks of NCM83, and void formation between cathode and SPE, are effectively mitigated by the LNTO layer. Therefore, the growth rate of interfacial resistance (RCEI) decreases from 37.6 Ω h-0.5 for bare NCM83 to 2.4 Ω h-0.5 for CNCM83 at 4.2 V. Moreover, 4.2 V PEO-based ASSPLBs achieve impressive cyclability with high capacity retention of 135 mAh g-1 (75%) even after 300 cycles at 0.5 C.

Computational approach inspired advancements of solid-state electrolytes for lithium secondary batteries: from first-principles to machine learning

The increasing demand for high-security, high-performance, and low-cost energy storage systems (EESs) driven by the adoption of renewable energy is gradually surpassing the capabilities of commercial lithium-ion batteries (LIBs). Solid-state electrolytes (SSEs), including inorganics, polymers, and composites, have emerged as promising candidates for next-generation all-solid-state batteries (ASSBs). ASSBs offer higher theoretical energy densities, improved safety, and extended cyclic stability, making them increasingly popular in academia and industry. However, the commercialization of ASSBs still faces significant challenges, such as unsatisfactory interfacial resistance and rapid dendrite growth. To overcome these problems, a thorough understanding of the complex chemical-electrochemical-mechanical interactions of SSE materials is essential. Recently, computational methods have played a vital role in revealing the fundamental mechanisms associated with SSEs and accelerating their development, ranging from atomistic first-principles calculations, molecular dynamic simulations, multiphysics modeling, to machine learning approaches. These methods enable the prediction of intrinsic properties and interfacial stability, investigation of material degradation, and exploration of topological design, among other factors. In this comprehensive review, we provide an overview of different numerical methods used in SSE research. We discuss the current state of knowledge in numerical auxiliary approaches, with a particular focus on machine learning-enabled methods, for the understanding of multiphysics-couplings of SSEs at various spatial and time scales. Additionally, we highlight insights and prospects for SSE advancements. This review serves as a valuable resource for researchers and industry professionals working with energy storage systems and computational modeling and offers perspectives on the future directions of SSE development.

Application of carbon-based adsorbents in the remediation of micro- and nanoplastics

Micro-nano plastics (MNPs) are emerging contaminants that can easily enter the food chain, posing risks to both the aquatic ecosystem and human health. Various physical, biological, and chemical methods have been explored to remove MNPs from water, and recently, adsorption technology has gained attention as an effective approach. Among the potential candidates, carbon-based adsorbent has emerged as a promising choice due to their low cost, eco-friendly nature, and sustainability. This paper summarizes recent advancements in MNP removal using carbon-based adsorbents, with a focus on the modification methods and adsorption mechanisms. Additionally, the factors influencing the adsorption performance and the methods for characterizing the adsorption mechanism are analyzed. Finally, the advantages and disadvantages of carbon-based adsorbents over other adsorbents are discussed, along with the current state of sustainable recycling and future research prospects.

A Multiscale, Dynamic Elucidation of Li Solubility in the Alloy and Metallic Plating Process

Li-containing alloys and metallic deposits offer substantial Li+ storage capacities as alternative anodes to commercial graphite. However, the thermodynamically in sequence, yet kinetically competitive mechanism between Li solubility in the solid solution and intermediate alloy-induced Li deposition remains debated, particularly across the multiple scales. The elucidation of the mechanism is rather challenging due to the dynamic alloy evolution upon the non-equilibrium, transient lithiation processes under coupled physical fields. Here, influential factors governing Li solubility in the Li-Zn alloy are comprehensively investigated as a demonstrative model, spanning from the bulk electrolyte solution to the ion diffusion within the electrode. Through real-time phase tracking and spatial distribution analysis of intermediate alloy/Li metallic species at varied temperatures, current densities and particle sizes, the driving force of Li solubility and metallic plating along the Li migration pathway are probed in-depth. This study investigates the correlation between kinetics (pronounced concentration polarization, miscibility gap in lattice grains) and rate-limiting interfacial charge transfer thermodynamics in dedicating the Li diffusion into the solid solution. Additionally, the lithiophilic alloy sites with the balanced diffusion barrier and Li adsorption energy are explored to favor the homogeneous metal plating, which provides new insights for the rational innovation of high-capacity alloy/metallic anodes.

Tailoring Practically Accessible Polymer/Inorganic Composite Electrolytes for All-Solid-State Lithium Metal Batteries: A Review

Highlights

The current issues and recent advances in polymer/inorganic composite electrolytes are reviewed. The molecular interaction between different components in the composite environment is highlighted for designing high-performance polymer/inorganic composite electrolytes. Inorganic filler properties that affect polymer/inorganic composite electrolyte performance are pointed out. Future research directions for polymer/inorganic composite electrolytes compatible with high-voltage lithium metal batteries are outlined.

Abstract

Solid-state electrolytes (SSEs) are widely considered the essential components for upcoming rechargeable lithium-ion batteries owing to the potential for great safety and energy density. Among them, polymer solid-state electrolytes (PSEs) are competitive candidates for replacing commercial liquid electrolytes due to their flexibility, shape versatility and easy machinability. Despite the rapid development of PSEs, their practical application still faces obstacles including poor ionic conductivity, narrow electrochemical stable window and inferior mechanical strength. Polymer/inorganic composite electrolytes (PIEs) formed by adding ceramic fillers in PSEs merge the benefits of PSEs and inorganic solid-state electrolytes (ISEs), exhibiting appreciable comprehensive properties due to the abundant interfaces with unique characteristics. Some PIEs are highly compatible with high-voltage cathode and lithium metal anode, which offer desirable access to obtaining lithium metal batteries with high energy density. This review elucidates the current issues and recent advances in PIEs. The performance of PIEs was remarkably influenced by the characteristics of the fillers including type, content, morphology, arrangement and surface groups. We focus on the molecular interaction between different components in the composite environment for designing high-performance PIEs. Finally, the obstacles and opportunities for creating high-performance PIEs are outlined. This review aims to provide some theoretical guidance and direction for the development of PIEs.

Improving the Electrochemical Stability of a Polyester-Polycarbonate Solid Polymer Electrolyte by Zwitterionic Additives

Rechargeable batteries with solid polymer electrolytes (SPEs), Li-metal anodes, and high-voltage cathodes like LiNi _x Mn _y Co _z O₂ (NMC) are promising next-generation high-energy-density storage solutions. However, these types of cells typically experience rapid failure during galvanostatic cycling, visible as an incoherent voltage noise during charging. Herein, two imidazolium-based zwitterions, with varied sulfonate-bearing chain length, are added to a poly(ε-caprolactone-co-trimethylene carbonate):LiTFSI electrolyte as cycling-enhancing additives to study their effect on the electrochemical stability of the electrolyte and the cycling performance of half-cells with NMC cathodes. The oxidative stability is studied with two different voltammetric methods using cells with inert working electrodes: the commonly used cyclic voltammetry and staircase voltammetry. The specific effects of the NMC cathode on the electrolyte stability is moreover investigated with cutoff increase cell cycling (CICC) to study the chemical and electrochemical compatibility between the active material and the SPE. Zwitterionic additives proved to enhance the electrochemical stability of the SPE and to facilitate improved galvanostatic cycling stability in half-cells with NMC by preventing the decomposition of LiTFSI at the polymer-cathode interface, as indicated by X-ray photoelectron spectroscopy (XPS).

Expanding the active charge carriers of polymer electrolytes in lithium-based batteries using an anion-hosting cathode

Ionic-conductive polymers are appealing electrolyte materials for solid-state lithium-based batteries. However, these polymers are detrimentally affected by the electrochemically-inactive anion migration that limits the ionic conductivity and accelerates cell failure. To circumvent this issue, we propose the use of polyvinyl ferrocene (PVF) as positive electrode active material. The PVF acts as an anion-acceptor during redox processes, thus simultaneously setting anions and lithium ions as effective charge carriers. We report the testing of various Li||PVF lab-scale cells using polyethylene oxide (PEO) matrix and Li-containing salts with different anions. Interestingly, the cells using the PEO-lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) solid electrolyte deliver an initial capacity of 108 mAh g⁻¹ at 100 μA cm⁻² and 60 °C, and a discharge capacity retention of 70% (i.e., 70 mAh g⁻¹) after 2800 cycles at 300 μA cm⁻² and 60 °C. The Li|PEO-LiTFSI|PVF cells tested at 50 μA cm⁻² and 30 °C can also deliver an initial discharge capacity of around 98 mAh g⁻¹ with an electrolyte ionic conductivity in the order of 10⁻⁵S cm⁻¹.

The energy content of secondary batteries is often limited by the charge carriers available in the system. Here, the authors employed an anion acceptor cathode for simultaneous use of electrolyte anions and cations as effective charge carriers in solid polymer electrolytes for lithium-based batteries.

Ferroelectric Engineered Electrode-Composite Polymer Electrolyte Interfaces for All-Solid-State Sodium Metal Battery

To enhance the compatibility between the polymer-based electrolytes and electrodes, and promote the interfacial ion conduction, a novel approach to engineer the interfaces between all-solid-state composite polymer electrolyte and electrodes using thin layers of ferroelectrics is introduced. The well-designed and ferroelectric-engineered composite polymer electrolyte demonstrates an attractive ionic conductivity of 7.9 × 10^-5 S cm^-1 at room temperature. Furthermore, the ferroelectric engineering is able to effectively suppress the growth of solid electrolyte interphase (SEI) at the interface between polymer electrolytes and Na metal electrodes, and it can also enhance the ion diffusion across the electrolyte-ferroelectric-cathode/anode interfaces. Notably, an extraordinarily high discharge capacity of 160.3 mAh g^-1 , with 97.4% in retention, is achieved in the ferroelectric-engineered all-solid-state Na metal cell after 165 cycles at room temperature. Moreover, outstanding stability is demonstrated that a high discharge capacity retention of 86.0% is achieved over 180 full charge/discharge cycles, even though the cell has been aged for 2 months. This work provides new insights in enhancing the long-cyclability and stability of solid-state rechargeable batteries.

Solid Polymer Electrolyte Reinforced with a Li1.3Al0.3Ti1.7(PO4)3-Coated Separator for All-Solid-State Lithium Batteries

Poly(ethylene oxide) (PEO)-based solid-state lithium batteries (SSLBs), accompanied by potential high energy density and reliable safety, have attracted wide attention. However, PEO-based solid-state electrolytes (SSEs) are hard to scale up due to their low oxidation stability, low ionic conductivity at room temperature, and relatively poor mechanical properties. Here, a PEO-based ceramic-polymer (PCP) composite SSE is designed. The porous Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP)-coated polyethylene (PE) separator is filled with PEO/lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) solution, which possesses both a robust mechanical property and processable flexibility. The results show the PCP membrane effectively suppresses the growth of lithium (Li) dendrites identified by a flat Li deposition. It is attributed to the robustness of the PCP membrane itself and the formation of a mixed ionic/electronic conducting interphase (MCI) intertwined with a solid electrolyte interface (SEI) between the PCP membrane and the Li anode. The MCI-SEI intertwined mixed phase facilitates the homogeneous Li deposition and enhances the cycle stability of the electrolyte/anode interface. Hence, the PCP membrane effectively prevents short-circuiting and shows a good cycling stability of more than 2000 h in a Li/PCP/Li symmetric cell with a current density of 0.2 mA cm^-2 at 60 °C. Moreover, the Li/PCP/LiFePO₄ all-solid-state battery shows a stable cycling performance with 160 mAh g^-1 at 0.2C after 200 cycles at 60 °C. The results show the purposed PCP membrane based on a LATP-coated PE separator is easy to be fabricated and could be practical for many applications.

In-Depth Mechanism Understanding for Potassium-Ion Batteries by Electroanalytical Methods and Advanced In Situ Characterization Techniques

The advancement of potassium ion batteries (PIBs) stimulated by the dearth of lithium resources is accelerating. Major progresses on the electrochemical properties are based on the optimization of electrode materials, electrolytes, and other components. More significantly, the prerequisites for optimizing these key compositions are in-depth and comprehensive exploration of electrochemical reaction processes, including the evolution of morphology and structure, phase transition, interface behaviors, and K⁺ movement, etc. As a result, the obtained K⁺ storage mechanism via analyzing aforementioned reaction processes sheds light on furthering practical application of PIBs. Typical electrochemical analysis methods are capable of obtaining physical and chemical characteristics. The advent of in situ electrochemical measurements enables dynamic observation and monitoring, thereby gaining extensive insights into the intricate mechanism of capacity degradation and interface kinetics. By coupling with these powerful electrochemical characterization techniques, inspiring works in PIBs will burgeon into wide realms of energy storage fields. In this review, some typical electroanalytical tests and in situ hyphenated measurements are described with the main concentration on how these techniques play a role in investigating the potassium storage mechanism for PIBs and achieving encouraging results.

In Situ and In Operando Techniques to Study Li-Ion and Solid-State Batteries: Micro to Atomic Level

This work summarizes the most commonly used in situ techniques for the study of Li-ion batteries from the micro to the atomic level. In situ analysis has attracted a great deal of interest owing to its ability to provide a wide range of information about the cycling behavior of batteries from the beginning until the end of cycling. The in situ techniques that are covered are: X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Scanning Transmission Electron Microscopy (STEM). An optimized setup is required to be able to use any of these in situ techniques in battery applications. Depending on the type of data required, the available setup, and the type of battery, more than one of these techniques might be needed. This study organizes these techniques from the micro to the atomic level, and shows the types of data that can be obtained using these techniques, their advantages and their challenges, and possible strategies for overcoming these challenges.

Thermal evolution of NASICON type solid-state electrolytes with lithium at high temperature via in situ scanning electron microscopy

We present the thermal evolution of two NASICON-type ceramics namely LATP (Li_1+xAl_xTi_2-x(PO₄)₃) and LAGP (Li_1+xAl_xGe_2-x(PO₄)₃) by monitoring the electrode-electrolyte interfaces (i.e., Li/LATP and Li/LAGP) at temperatures up to 330 °C via in situ scanning electron microscopy, post-mortem energy-dispersive spectroscopy, and X-ray diffraction. Upon melting of Li and contacting electrolytes, LAGP decomposes completely to form Li based alloys, while LATP is partially decomposed without alloying.

Solid Polymer Electrolytes with High Conductivity and Transference Number of Li Ions for Li-Based Rechargeable Batteries

Smart electronics and wearable devices require batteries with increased energy density, enhanced safety, and improved mechanical flexibility. However, current state-of-the-art Li-based rechargeable batteries (LBRBs) use highly reactive and flowable liquid electrolytes, severely limiting their ability to meet the above requirements. Therefore, solid polymer electrolytes (SPEs) are introduced to tackle the issues of liquid electrolytes. Nevertheless, due to their low Li⁺ conductivity and Li⁺ transference number (LITN) (around 10^-5 S cm^-1 and 0.5, respectively), SPE-based room temperature LBRBs are still in their early stages of development. This paper reviews the principles of Li⁺ conduction inside SPEs and the corresponding strategies to improve the Li⁺ conductivity and LITN of SPEs. Some representative applications of SPEs in high-energy density, safe, and flexible LBRBs are then introduced and prospected.

Inorganic Fillers in Composite Gel Polymer Electrolytes for High-Performance Lithium and Non-Lithium Polymer Batteries

Among the various types of polymer electrolytes, gel polymer electrolytes have been considered as promising electrolytes for high-performance lithium and non-lithium batteries. The introduction of inorganic fillers into the polymer-salt system of gel polymer electrolytes has emerged as an effective strategy to achieve high ionic conductivity and excellent interfacial contact with the electrode. In this review, the detailed roles of inorganic fillers in composite gel polymer electrolytes are presented based on their physical and electrochemical properties in lithium and non-lithium polymer batteries. First, we summarize the historical developments of gel polymer electrolytes. Then, a list of detailed fillers applied in gel polymer electrolytes is presented. Possible mechanisms of conductivity enhancement by the addition of inorganic fillers are discussed for each inorganic filler. Subsequently, inorganic filler/polymer composite electrolytes studied for use in various battery systems, including Li-, Na-, Mg-, and Zn-ion batteries, are discussed. Finally, the future perspectives and requirements of the current composite gel polymer electrolyte technologies are highlighted.

Carbon and germanium nanocages as anode electrodes in sodium-ion and potassium-ion batteries

Here, the potential of C₃₆, C₄₈, and Ge₄₈ nanocages as anodes of Na-ion battery (IB) and K-IB are investigated by DFT/M06-2X and DFT/B3LYP in gas and solvent. The E_Formation and E_Gap of C₃₆, C₄₈, and Ge₄₈ nanocages are investigated by theoretical methods. The vertical and adiabatic EA and IP of C₃₆, C₄₈, and Ge₄₈ nanocages are examined in gas and solvent. The E_ad of Na⁺ and K⁺ on inner and outer positions of C₃₆, C₄₈, and Ge₄₈ nanocages are investigated. The V_cell and C_Theory of C₃₆, C₄₈, and Ge₄₈ as anodes of batteries are investigated. The results of this paper proposed the nano materials (C₄₈ and Ge₄₈ nanocage) as anodes of Na-IB and K-IB with higher C_Theory and V_cell than graphene nanosheet.

A General Strategy of Anion-Rich High-Concentration Polymeric Interlayer for High-Voltage, All-Solid-State Batteries

All-solid-state batteries are promising energy storage systems as a power source for future electric applications. However, the solid electrolytes have suffered from oxidative vulnerability at the catalytic cathode's surface, particularly at the high-voltage charging process. The poor charge transport and the contact issue at the electrolyte/electrode interface also hamper fully utilizing high-energy-density batteries. In this work, a general design of a high-concentration polymeric interlayer is developed. The interactions between a number of anions in the high-salt-concentration and the polymer chain's functional groups have shown outstanding physicochemical properties, including the rich solvation sites and conductive nanochannels, which Li⁺ ions can coordinate to or conduct through. The high-concentration polymeric interlayer is also highly resistant to oxidation (up to 5 V) that leads to significant improvement in cycle life with various cathodes, including LiNi_1/3Co_1/3Mn_1/3O₂, LiCoO₂ and LiFePO₄, demonstrating a high Coulombic efficiency over 99.9%.

On high-temperature evolution of passivation layer in Li-10 wt % Mg alloy via in situ SEM-EBSD

Li-10 wt % Mg alloy (Li-10 Mg) is used as an anode material for a solid-state battery with excellent electrochemical performance and no evidence of dendrite formation during cycling. Thermal treatment of Li metal during manufacturing improves the interfacial contact between a Li metal electrode and solid electrolyte to achieve an all solid-state battery with increased performance. To understand the properties of the alloy passivation layer, this paper presents the first direct observation of its evolution at elevated temperatures (up to 325°C) by in situ scanning electron microscopy. We found that the morphology of the surface passivation layer was unchanged above the alloy melting point, while the bulk of the material below the surface was melted at the expected melting point, as confirmed by in situ electron backscatter diffraction. In situ heat treatment of Li-based materials could be a key method to improve battery performance.

Rapid Online Solid-State Battery Diagnostics with Optically Pumped Magnetometers

Solid-state battery technology is motivated by the desire to deliver flexible power storage in a safe and efficient manner. The increasingly widespread use of batteries from mass production facilities highlights the need for a rapid and sensitive diagnostic tool for identifying battery defects. We demonstrate the use of atomic magnetometry to measure the magnetic fields around miniature solid-state battery cells. These fields encode information about battery manufacturing defects, state of charge, and impurities, and they can provide important insights into battery aging processes. Compared with SQUID-based magnetometry, the availability of atomic magnetometers, however, highlights the possibility of constructing a low-cost, portable, and flexible implementation of battery quality control and characterization technology.

Temperature-Dependent Chemical and Physical Microstructure of Li Metal Anodes Revealed through Synchrotron-Based Imaging Techniques

The Li metal anode has been long sought-after for application in Li metal batteries due to its high specific capacity (3860 mAh g^-1 ) and low electrochemical potential (-3.04 V vs the standard hydrogen electrode). Nevertheless, the behavior of Li metal in different environments has been scarcely reported. Herein, the temperature-dependent behavior of Li metal anodes in carbonate electrolyte from the micro- to macroscales are explored with advanced synchrotron-based characterization techniques such as X-ray computed tomography and energy-dependent X-ray fluorescence mapping. The importance of testing methodology is exemplified, and the electrochemical behavior and failure modes of Li anodes cycled at different temperatures are discussed. Moreover, the origin of cycling performance at different temperatures is identified through analysis of Coulombic efficiencies, surface morphology, and the chemical composition of the solid electrolyte interphase in quasi-3D space with energy-dependent X-ray fluorescence mappings coupled with micro-X-ray absorption near edge structure. This work provides new characterization methods for Li metal anodes and serves as an important basis toward the understanding of their electrochemical behavior in carbonate electrolytes at different temperatures.

Developing high safety Li-metal anodes for future high-energy Li-metal batteries: strategies and perspectives

Developing high-safety Li-metal anodes (LMAs) are extremely important for the application of high-energy Li-metal batteries. The recently state-of-the-art technologies, strategies and perspectives for developing LMAs are comprehensively summarized in this review.