Eliminating interfacial O-involving degradation in Li-rich Mn-based cathodes for all-solid-state lithium batteries

Three-Dimensional Continuous Ion Transport Skeleton-Reinforced Composite Solid Electrolyte for High-Performance Solid-State Lithium Metal Batteries

The Li1.3Al0.3Ti1.7(PO4)3 (LATP) electrolyte is recognized as a highly promising solid-state electrolyte for next-generation solid-state lithium batteries due to its high ionic conductivity, low cost, and exceptional air stability. Unfortunately, its practical application is impeded by significant grain boundary impedance and interfacial instability with lithium metal. In this study, we introduced a cost-effective template method to fabricate a three-dimensional LATP (3D-LATP) skeleton featuring continuous porosity, which was combined with the polymer poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) to fabricate a three-dimensional composite solid electrolyte (3D-CSE) exhibiting enhanced flexibility and superior interfacial contact. The 3D-LATP skeleton acts as an active filler, establishing continuous transport pathways for lithium ions within the electrolyte and substantially increasing the room-temperature ionic conductivity to 6.89 × 10-4 S cm-1. Furthermore, the nonflammability of the 3D-LATP skeleton significantly enhances the thermal stability of the electrolyte. Additionally, the inclusion of the PVDF-HFP polymer improves interfacial contact between the LATP skeleton and the electrodes, thereby mitigating erosion of the LATP skeleton by the lithium metal anode in Li|Li symmetric batteries and LiFePO4|Li full batteries. Consequently, the Li|3D-CSE|Li symmetric battery demonstrated stable lithium plating-stripping cycles for over 4000 h at 0.1 mA cm-2. Moreover, the LiFePO4|3D-CSE|Li full battery exhibited reliable cycling performance over 500 cycles at 0.5C. This high-performance 3D composite electrolyte highlights the potential of LATP for high-energy-density solid-state lithium metal batteries.

Enhanced Electrochemical Stability of Sulfide Electrolytes with Surface Modification for High-Performance LiNiO₂ Based All-Solid-State Lithium Batteries

All-solid-state lithium batteries (ASSLBs) equipped with layered Ni-rich cathodes hold great promise for achieving high-specific energy and enhanced safety. Although LiNiO2 (LNO) cathode theoretically offers superior specific capacity (≈275 mAh g-1) and cost efficiency, its practical application in ASSLBs is hindered by significant interfacial incompatibility with solid electrolytes, resulting in parasitic side reactions and sluggish charge transport, particularly under high-voltage operation. Here, a facile ball-milling strategy is presented to engineer an in situ protective layer on Li5.5PS4.5Cl1.5 (LPSC) through a spontaneous chemical reaction with Li2SO4, which effectively mitigates interfacial electrochemical instability. This modified electrolyte enables ASSLBs with LNO to achieve a record-high discharge capacity of 231.3 mAh g-1 at 0.2 C and 45 °C, alongside remarkable cycling stability (95% capacity retention after 200 cycles at 4.4 V). Additionally, even under an ultra-high voltage of 4.6 V, the battery can still retain 95% capacity over 140 cycles. Multimodal spectroscopic analyses confirm that the designed coating suppresses interfacial decomposition while maintaining rapid Li⁺ transport. This work establishes a scalable, cost-effective approach to interfacial engineering, unlocking the potential of LNO-based ASSLBs for high-specific energy applications.

Morphological Control to Enhance Diffusion Kinetics and Structural Stability on Li-Rich Layered Oxides Cathode for Long-Cycle Batteries

The morphology of cathode materials usually plays a crucial role in determining their electrochemical performance. It is a major research focus aimed at improving Li+ diffusion kinetics and enhancing structural stability on Li-rich layered oxides cathode. In this work, through finite element analysis simulations, thin plate particles with a lower ratio of active planes exhibit a more uneven Li+ concentration distribution and severe stress accumulation between the active and inactive planes after almost complete deintercalation. Columnar polyhedron and thin plate shapes were synthesized by controlling the precursor components using the typical carbonate and hydroxide coprecipitation method, respectively. It is found that the columnar polyhedron shape has a higher proportion of active planes compared to the thin plate shape. As a result, materials with a higher proportion of active planes exhibit superior Li+ diffusion kinetics and enhanced stability during cycling; specifically, the more satisfied Li+ diffusion coefficient and 88.3% capacity retention ratio following 200 cycles, while those with fewer active planes face challenges in maintaining capacity retention due to structural degradation, characterized by scanning transmission electron microscopy-high angle annular dark field and geometric phase analysis. Further research into optimizing the morphology for improved electrochemical properties is warranted.

Amorphous-Nanocrystalline Fluorinated Halide Electrolytes with High Ionic Conductivity and High-Voltage Stability

All-solid-state sodium-ion batteries (ASSSIBs) offer a cost-effective, scalable alternative to rechargeable lithium-ion batteries, but their advancement requires solid electrolytes with high ionic conductivity, wide electrochemical stability, and robust interfacial compatibility. Here, a fluorine-doped halide solid electrolyte (2NaF-ZrCl4, 2-NFZC) featuring an amorphous-nanocrystalline structure with high ionic conductivity (2.35 × 10-4 S cm-1 at 25 °C) and good high-voltage stability is presented. Fluorine doping in 2-NFZC promotes Zr-F bonding with limited Na-F interaction, which facilitates fast Na-ion transport through disordered regions and the NaF/amorphous phase interface. Paired with a NaNi1/3Fe1/3Mn1/3O2 cathode, a Na15Sn4 anode, and a Na3PS4 anode interlayer, the all-solid-state cell with the 2-NFZC electrolyte demonstrates a discharged capacity of 137.1 mAh g-1, 81.1% capacity retention over 600 cycles, and suppressed interfacial side reactions. These findings highlight the potential of fluorine doping in designing advanced solid electrolytes for high-performance all-solid-state Na-ion batteries.

Crosslinked Hetero-Chain Polymeric Interphase Enables the Stable Cycling of Li-Rich Mn-Based Lithium Metal Batteries

The lithium-rich manganese-based layered oxide (LRMO) cathode shows grar promise for high-energy density and environment-friendly batteries due to its cation and anion redox. However, it suffers from continuous electrolyte consumption and capacity decay, especially at high mass loadings (>10 mg cm-2). Conventional electrolyte/interphase strategies fail to address the structural characteristics of LRMO, limiting its practical application. Here, we reveal the specific requirements for cathode electrolyte interphase (CEI) of LRMO and accordingly design a non-fluorinated additive, 2,4,6-trivinyl-2,4,6-trimethylcyclotrisiloxane (TVTMS). TVTMS could form a crosslinked hetero-chain polymeric CEI (CHP-CEI) through ring-opening polymerization and ethylene group crosslinking, offering a unique balance of high robustness, flexibility, and mechanical energy dissipation, which could not be achieved by conventional additives. Therefore, the cracking of LRMO cathode, gas release and transition metal dissolution were effectively mitigated. It should be noted that, for the first time to our knowledge, we employed the single-particle aerosol mass spectrometry (SPAMS) to study CEI components, especially the organic/polymer species. The Li|LRMO cells based on CHP-CEI display a lifespan >825 cycles with remained capacity of 204 mAh g-1 and the cells with high-loading cathode (12 mg cm-2) achieve stable cycling >145 cycles with 80% capacity retention, which surpasses the performance of previously reported electrolytes.

Boosting Initial Coulombic Efficiency in Li-Rich Mn-based Cathodes by Tuning Orbital Hybridization

Li-rich manganese-based oxides (LRMO) are promising cathode materials for next-generation lithium-ion batteries due to their high-capacity and low-cost merits. However, the low initial coulombic efficiency (ICE) and irreversible oxygen release of LRMO severely hinder their commercialization processes. Here, we employ glyoxal treatment to modulate the hybridization between transition metal (TM) 3d and oxygen (O) 2p orbitals in LRMO. This approach is found to reduce the Co/Mn t2g-O 2p hybridization in LRMO while simultaneously activating the Co2+/Co3+ redox below the Fermi level. Our findings demonstrate that tuning TM 3d-O 2p orbital hybridization can be a viable approach to improve the ICE of LMRO. Specifically, the ICE of LRMO can be elevated from 85.3% to 102.5%, and a high specific capacity of 291.2 mAh g-1 can be achieved at 0.1 C. Moreover, the treated LRMO cathodes exhibit significantly enhanced capacity retention.

Modulating Coupled Polyhedral Distortion in Li-Rich Cathodes for Synergistically Inhibiting Capacity and Voltage Decay

Achieving significant enhancements in both capacity and voltage stability remains a formidable challenge for Li-rich layered cathodes. The severe performance degradation is attributed to large lattice strain, irreversible oxygen release and transition metal migration, but the most critical factor responsible for structural destabilization is still elusive. Here, based on density functional theory calculations, machine learning and experimental validation, a multi-hierarchy screening of complex multi-element doping systems is developed from electrochemical activity, lattice strain, oxygen stability and transition metal migration barrier. It is further identified that the coupled polyhedral distortion parameter D+σ2 of the substitution element is the most significant feature that affects the structural stability during cycling. The Li-rich layered cathode developed based on the predicted results exhibits remarkable long-term capacity stability (95.8% capacity retention over 300 cycles) and negligible voltage loss (0.02% voltage decay per cycle). This study provides a general approach by modulating coupled polyhedral distortion for the rational design of cathode materials and can be expanded to the discovery of other advanced electrodes.

Morphology Engineering in Cobalt-Free Li-Rich Oxides for High-Capacity and Strain-Tolerant Cathodes

Morphology engineering plays a critical role in enhancing ionic diffusion kinetics and activating oxygen redox activity in cobalt-free lithium-rich layered oxides (LROs), addressing their intrinsic limitations for high-energy-density batteries. Herein, a morphology-engineering strategy is proposed to synthesize cobalt-free LRO cathodes with radially arranged primary grains (LRO-RA) and short rod-like grains (LRO-SR). The radial architecture of LRO-RA establishes fast Li+ diffusion pathways, as evidenced by its near-identical Li+ diffusion coefficient to LRO-SR despite dominating oxygen redox contributions. This accelerated ion transport facilitates reversible anionic redox, yielding a 79 mAh g-1 higher initial discharge capacity (0.1C) and a 50.6 mV lower O oxidation potential compared to LRO-SR. Advanced spectroscopic and diffraction analyses confirm that the radial morphology stabilizes anionic redox, minimizes MnO6 distortion, and mitigates strain accumulation. Consequently, LRO-RA achieves a 94.8% capacity retention after 400 cycles (1C), far exceeding LRO-SR (75.6%), with mitigated voltage decay. Post-cycling analysis confirms that the dense radial grains resist electrolyte infiltration and phase transformation, preserving structural integrity. This work elucidates how morphology-driven ion transport optimization amplifies oxygen redox reversibility, offering a universal design principle for high-capacity Li-rich cathodes.

Realizing a 3 C Fast-Charging Practical Sodium Pouch Cell

Sodium-ion batteries (SIBs), endowed with relatively small Stokes radius and low desolvation energy of Na+, are reckoned as a promising candidate for fast-charging endeavors. However, the C-rate charging capability of practical energy-dense sodium-ion pouch cells is currently limited to ≤1 C, due to the high propensity for detrimental metallic Na plating on the hard carbon (HC) anode at elevated rates. Here, an ampere-hour-level sodium-ion pouch cell capable of 3 C charging is successfully developed via phosphorus (P)-sulfur (S) interphase chemistry. By rational electrolyte regulation, desired P-S constituents, namely, Na3PO4 and Na2SO4, are generated in the solid-electrolyte interphase with favorable Na+ interface kinetics. Specifically, Na+ desolvation energy barrier has been greatly lowered by the weak ion-solvent coordination near the inner Helmholtz plane on Na3PO4 interphase, while Na2SO4 expedites charge carrier mobility due to its intrinsically high ionic conductivity. Consequently, an energy-dense (126 Wh kg-1) O3-Na(Ni1/3Fe1/3Mn1/3)O2||HC pouch cell capable of 3 C charging (100 % state of charge) without Na plating can be achieved, with a great capacity retention of 91.5 % over 200 cycles. Further, the assembled power-type Na3V2(PO4)3||HC pouch cell displays an impressive fast-charging capability of 50 C, which surpasses that of previously reported high-power SIBs. This work serves as an enlightenment for developing fast-charging SIBs.

Gradient Design with Low-Tortuosity Overcoming Kinetic Limitations in High-Loading Solid-State Cathodes

The extensive commercialization of practical solid-state batteries (SSBs) necessitates the development of high-loading solid-state cathodes with fast charging capability. However, electrochemical kinetics are severely delayed in thick cathodes due to tortuous ion transport pathways and slow solid-solid ion diffusion, which limit the achievable capacity of SSBs at high current densities. In this work, we propose a conductivity gradient cathode with low-tortuosity to enable facile ion transport and counterbalance ion concentration gradient, thereby overcoming the kinetic limitations and achieving fast charging capabilities in thick cathodes. The LiNi0.8Co0.1Mn0.1O2 cathodes deliver a room-temperature (RT) capacities of 147 and 110 mAh g-1 at 5 C and 10 C, respectively, and meanwhile achieve a RT areal capacity of 3.3 mAh cm-2 at 3 C, enabling SSBs simultaneously high energy and power densities. The universality of this strategy is demonstrated in LiFePO4 cathodes, providing a novel solution for fast charging and large-scale application of high-loading SSBs.

Surface-Conducting Lithium Superionic Conductors for Solid-State Batteries

Bulk Li+-conducting lithium superionic conductors are susceptible to disruption by grain boundaries and interparticle porosity, necessitating high densification and consequently limiting the gravimetric energy density of solid-state batteries. Here, we discovered a new class of surface-conducting lithium superionic conductors achieved through surface chemisorption. After bonding with ligands, surface atoms of inert substrates become binding sites for lithium salt dissociation and hopping sites for fast surface Li+ diffusion, transforming inert materials into surface-conducting Li+ conductors. Using two-dimensional TiO2 nanosheets as a proof of concept, we show that ethylene glycolate-chemisorbed TiO2 significantly enhances lithium salt dissociation and promotes fast Li+ hopping between surface oxygen atoms, achieving a high surface ion mobility of 3.61 × 10-7 cm2·V-1·s-1─an improvement of 600% over the bulk Li+ mobility of Li7La3Zr2O12 solid oxide electrolytes. Benefiting from surface Li+ conduction, an ultralight oxide aerogel solid-state electrolyte was developed with an unprecedented low density of 0.29 g·cm-3, which is only 25% of that of liquid electrolytes and 5.7% of garnet-type solid electrolytes. A LiFePO4-based solid-state battery utilizing this new electrolyte exhibits a significantly high energy density of ∼295 Wh·kg-1, achieving 160% of that of a Li7La3Zr2O12-based solid-state battery even with the same electrolyte thickness. Furthermore, this guideline for designing surface-conducting superionic conductors is generalizable and can be extended to diverse cations and substrates, promising lightweight, highly conductive solid-state electrolytes with broad implications beyond solid-state batteries.

Towards Stable Metal-I2 Battery: Design of Iodine-Containing Functional Groups for Enhanced Halogen Bond

The redox chemistries of iodine have attracted tremendous attention for charge storage owing to their high theoretical specific capacity and natural abundance. However, the practical capacity and cycle life are greatly limited by the active mass loss originating from the dissolved iodine species in either non-aqueous or aqueous batteries. Despite intensive progress in physical and physicochemical confinements of iodine species (I2/I3 -/I-), less attention has been paid to confining iodine species beyond the host-iodine interface, inhibiting further development of iodine cathodes with high I2 contents. Here a halogen bond (XB)- enhanced design concept is proposed between I2 molecules to achieve stable cycling performances, as exemplified by the Na-I2 battery. The enhanced XB is derived from the incorporation of -B(OH)I3 groups in highly integrated porous carbon/I2 cathode (HOCF-BIn), which can generate extended interactions between -B(OH)I3 and following I2 molecules. Due to the strong intermolecular force between I2 molecules, the HOCF-BIn cathodes exhibit substantially strengthened I2/I3 -/I- confinement, enabling outstanding cycling stability at I2 loading ranging from 1.8 to 6.2 mg cm-2. This findings demonstrate a functional group to manipulate XB chemistry within I2 molecules and polyiodides for stable and low-cost metal-iodine batteries.

Fundamentals, Status and Promise of Li-Rich Layered Oxides for Energy-Dense Li-Ion Batteries

Li-ion batteries (LIBs) are the dominant electrochemical energy storage devices in the global society, in which cathode materials are the key components. As a requirement for higher energy-dense LIBs, Li-rich layered oxides (LLO) cathodes that can provide higher specific capacity are urgently needed. However, LLO still face several significant challenges before bringing these materials to market. In this Review, the fundamental understanding of LLO is described, with a focus on the physical structure-electrochemical property relationships. Specifically, the various strategies toward reversible anionic redox is discussed, highlighting the approaches that take the basic structure of the battery into account. In addition, the application for all-solid-state batteries and consider the prospects for LLO is assessed.

Ductile Inorganic Solid Electrolytes for All-Solid-State Lithium Batteries

Solid electrolytes, as the core of all-solid-state batteries (ASSBs), play a crucial role in determining the kinetics of ion transport and the interface compatibility with cathodes and anodes, which can be subdivided into catholytes, bulk electrolytes, and anolytes based on their functional characteristics. Among various inorganic solid electrolytes, ductile solid electrolytes, distinguished from rigid oxide electrolytes, exhibit excellent ion transport properties even under cold pressing, thus holding greater promise for industrialization. However, the challenge lies in finding a ductile solid electrolyte that can simultaneously serve as catholyte, bulk electrolyte, and anolyte. Fortunately, due to the immobility of solid electrolytes, combining multiple types of solid electrolytes allows for leveraging their respective advantages. In this review, we discuss five types of solid electrolytes, sulfides, halides, nitrides, antiperovskite-type, and complex hydrides, and the challenges and superiorities for these electrolytes are also addressed. The impact of pressure on ASSBs has been systematically discussed. Furthermore, the suitability of electrolytes as the catholyte, bulk electrolyte, and anolyte is discussed based on their functional characteristics and physicochemical properties. This discussion aims to deepen our understanding of solid electrolytes, enabling us to harness the advantages of various types of solid electrolytes and develop practical, high-performance ASSBs.

In-situ positive electrode-electrolyte interphase construction enables stable Ah-level Zn-MnO2 batteries

Engineering the formulation of an Mn-based positive electrode is a viable strategy for producing an efficient aqueous zinc-ion battery. However, Mn dissolution and the byproducts result in capacity fading, thus limiting its electrochemical performances. To solve the undesirable issues, the concept of in-situ forming the positive electrode/electrolyte interface on the commercial MnO2 is designed, with the help of introducing the Dioctyl Phthalate into the ZS-based electrolyte (2 M ZnSO4 + 0.2 M MnSO4), designated as ZS-DOP electrolyte. An advanced three-dimensional chemical and imaging analysis on a model material reveals the dynamic formation of positive electrode/electrolyte interface. The formed organic interface effectively suppresses the corrosion of the electrolytes with its hydrophobicity, and adjusts the pH value according to Le Chatelier's Principle to inhibit the production of by-products. Specifically, the pouch cell assembled with the ZS-DOP electrolyte attains a reversible capacity of ~2.5 Ah and powers the unmanned aerial vehicle. Furthermore, photovoltaic energy storage applications deliver a stable capacity of 0.5 Ah and realize the power supply for mobile phones and other electronic devices. Our results facilitate the development of in-situ surface protection on the positive electrode in aqueous zinc-ion battery, providing insights into its practical application.

Ferrocyanide "Skin"-Mediated Anticatalysis: Mitigating Self-Discharge in Aqueous Electrochemical Devices

The interest in aqueous energy storage devices is surging due to their exceptional safety profile. However, in aqueous energy storage systems, interfacial side reactions, predominantly attributed to the oxygen evolution reaction (OER), result in significant self-discharge, which is concomitant with the deterioration of both voltage and capacity. Herein, we propose the construction of a ferrocyanide "skin" on transition metal compounds (TMCs) to mitigate this issue. This engineered "skin" creates Fe-C≡N terminations, initiating a new reaction pathway featured by the bonding process of N-O and N-H bonds. This reaction pathway presents a significant energy barrier, effectively shielding the active sites for the OER from H2O molecules and hydroxyl ions. Taking NiO as an example, the ferrocyanide "skin" effectively suppresses the undesired phase transition from NiOOH to Ni(OH)2 during the idling process of a fully charged electrode, enabling the as-modified electrode to achieve a remarkable voltage retention of 80.0% after 1 week of idling within a device. Furthermore, this concept demonstrates extensive applicability, extending to a range of TMC materials, including but not limited to manganese oxide, vanadium oxide, and nickel cobalt oxide. These findings highlight the efficacy of the ferrocyanide "skin" design strategy as a broadly applicable paradigm for suppressing H2O-induced undesirable phase transitions in aqueous energy storage devices.

Construction of Multifunctional Conductive Carbon-Based Cathode Additives for Boosting Li6PS5Cl-Based All-Solid-State Lithium Batteries

The electrochemical performance of all-solid-state lithium batteries (ASSLBs) can be prominently enhanced by minimizing the detrimental degradation of solid electrolytes through their undesirable side reactions with the conductive carbon additives (CCAs) inside the composite cathodes. Herein, the well-defined Mo3Ni3N nanosheets embedded onto the N-doped porous carbons (NPCs) substrate are successfully synthesized (Mo-Ni@NPCs) as CCAs inside LiCoO2 for Li6PSC5Cl (LPSCl)-based ASSLBs. This nano-composite not only makes it difficult for hydroxide groups (-OH) to survive on the surface but also allows the in situ surface reconstruction to generate the ultra-stable MoS2-Mo3Ni3N heterostructures after the initial cycling stage. These can effectively prevent the occurrence of OH-induced LPSC decomposition reaction from producing harmful insulating sulfates, as well as simultaneously constructing the highly-efficient electrons/ions dual-migration pathways at the cathode interfaces to facilitate the improvement of both electrons and Li+ ions conductivities in ASSLBs. With this approach, fine-tuned Mo-Ni@NPCs can deliver extremely outstanding performance, including an ultra-high first discharge-specific capacity of 148.61 mAh g-1 (0.1C), a high Coulombic efficiency (94.01%), and a capacity retention rate after 1000 cycles still attain as high as 90.62%. This work provides a brand-new approach of "conversion-protection" strategy to overcome the drawbacks of composite cathodes interfaces instability and further promotes the commercialization of ASSLBs.

High Configuration Entropy Promises Electrochemical Stability of Chloride Electrolytes for High-Energy, Long-Life All-Solid-State Batteries

Solid-state electrolytes (SSEs) with high ionic conductivity, stability, and interface compatibility are indispensable for high-energy-density and long-life all-solid-state batteries (ASSBs), yet there are scarce SSEs with sufficient ionic conductivity and electrochemical stability. In this study, with a high-entropy SSE (HE-SSE, Li2.9In0.75Zr0.1Sc0.05Er0.05Y0.05Cl6), we show the high configuration entropy has a thermodynamically positive relationship with the high-voltage stability. As a result, the ASSBs with HE-SSE and high-voltage cathode materials exhibit superior high-voltage and long-cycle stability, achieving 250 cycles with 81.4 % capacity retention when charged to 4.8 V (vs. Li+/Li), and even 5000 cycles if charged to 4.6 V (vs. Li+/Li). Experimental characterizations and density functional theory calculations confirm that the HE-SSE greatly suppresses the high-voltage degradation of SSE at the interface, promoting the high-voltage stability coordinately through high entropy and interface stability. The high entropy design offers a general strategy to simultaneously improve the high-voltage stability and ionic conductivity of SSEs, creating an avenue to building high-energy and long-life ASSBs.

Recent Progress and Challenges of Li-Rich Mn-Based Cathode Materials for Solid-State Lithium-Ion Batteries

Li-rich Mn-based (LRM) cathode materials, characterized by their high specific capacity (>250 mAh g-¹) and cost-effectiveness, represent promising candidates for next-generation lithium-ion batteries. However, their commercial application is hindered by rapid capacity degradation and voltage fading, which can be attributed to transition metal migration, lattice oxygen release, and the toxicity of Mn ions to the anode solid electrolyte interphase (SEI). Recently, the application of LRM cathode in all-solid-state batteries (ASSBs) has garnered significant interest, as this approach eliminates the liquid electrolyte, thereby suppressing transition metal crosstalk and solid-liquid interfacial side reactions. This review first examines the historical development, crystal structure, and mechanisms underlying the high capacity of LRM cathode materials. It then introduces the current challenges facing LRM cathode and the associated degradation mechanisms and proposes solutions to these issues. Additionally, it summarizes recent research on LRM materials in ASSBs and suggests strategies for improvement. Finally, the review discusses future research directions for LRM cathode materials, including optimized material design, bulk doping, surface coating, developing novel solid electrolytes, and interface engineering. This review aims to provide further insights and new perspectives on applying LRM cathode materials in ASSBs.

Boosting Anionic Redox Reactions of Li-Rich Cathodes through Lattice Oxygen and Li-Ion Kinetics Modulation in Working All-Solid-State Batteries

The use of lithium-rich manganese-based oxides (LRMOs) as the cathode in all-solid-state batteries (ASSBs) holds great potential for realizing high energy density over 600 Wh kg-1. However, their implementation is significantly hindered by the sluggish kinetics and inferior reversibility of anionic redox reactions of oxygen in ASSBs. In this contribution, boron ions (B3+) doping and 3D Li2B4O7 (LBO) ionic networks construction are synchronously introduced into LRMO materials (LBO-LRMO) by mechanochemical and subsequent thermally driven diffusion method. Owing to the high binding energy of B─O and high-efficiency ionic networks of nanoscale LBO complex in cathode materials, the as-prepared LBO-LRMO displays highly reversible and activated anionic redox reactions in ASSBs. The designed LBO-LRMO interwoven structure enables robust phase and LBO-LRMO|solid electrolyte interface stability during cycling (over 80% capacity retention after 2000 cycles at 1.0 C with a voltage range of 2.2-4.7 V vs Li/Li+). This contribution affords a fundamental understanding of the anionic redox reactions for LRMO in ASSBs and offers an effective strategy to realize highly activated and reversible oxygen redox reactions in LRMO-based ASSBs.

Electrolyte Design Enables Rechargeable LiFePO4/Graphite Batteries from -80 °C to 80 °C

Lithium iron phosphate (LFP)/graphite batteries have long dominated the energy storage battery market and are anticipated to become the dominant technology in the global power battery market. However, the poor fast-charging capability and low-temperature performance of LFP/graphite batteries seriously hinder their further spread. These limitations are strongly associated with the interfacial lithium (Li)-ion transport. Here we report a wide-temperature-range ester-based electrolyte that exhibits high ionic conductivity, fast interfacial kinetics and excellent film-forming ability by regulating the anion chemistry of Li salt. The interfacial barrier of the battery is quantitatively unraveled by employing three-electrode system and distribution of relaxation time technique. The superior role of the proposed electrolyte in preventing Li0 plating and sustaining homogeneous and stable interphases are also systematically investigated. The LFP/graphite cells exhibit rechargeability in an ultrawide temperature range of -80 °C to 80 °C and outstanding fast-charging capability without compromising lifespan. Specially, the practical LFP/graphite pouch cells achieve 80.2 % capacity retention after 1200 cycles (2 C) and 10-min charge to 89 % (5 C) at 25 °C and provide reliable power even at -80 °C.

Robust I···H-O Intramolecular Halogen Bond Boosts Reversible I3-/I- Redox Behavior for Sustainable Potassium-Iodine Batteries

Potassium-iodine batteries show great promise as alternatives for next-generation battery technology, owing to their high power density and environmental sustainability. Nevertheless, they suffer from polyiodide dissolution and the multistep electrode fabrication process, which leads to severe performance degradation and limitations in mass-market adoption. Herein, we report a simple "solution-adsorption" strategy for scale-up production of Ti3C2(OH)x-wrapped carbon nanotube paper (CNP), as an economic host for strengthening the iodine encapsulation. The cutting-edge characterizations and theoretical calculation results reveal that CNP exhibits great affinity to the electrochemically active I3-/I- redox couple, while the Ti-OH functional groups on MXene restrict the dissolution of polyiodides through forming the stable I···H-O intramolecular halogen bond. Benefiting from such a synergistic effect, the free-standing electrode ensures the reversible redox chemistry for developing high-performing potassium-iodine batteries. The fabricated pouch cell (100 mAh) shows a high energy density (130 Wh kg-1) with a full charge/discharge of 10 min, outperforming state-of-the-art new battery systems that require both high energy/power density. Such a potassium-iodine battery reduces the cost to 255 US$ kW h-1, which is much lower than that of the cathode materials in lithium-ion batteries and offers a sustainable option for grid-scale energy storage.

Reversible Configurations of 3-Coordinate and 4-Coordinate Boron Stabilize Ultrahigh-Ni Cathodes with Superior Cycling Stability for Practical Li-Ion Batteries

Ultrahigh-Ni layered oxide cathodes are the leading candidate for next-generation high-energy Li-ion batteries owing to their cost-effectiveness and ultrahigh capacity. However, the increased Ni content causes larger volume variations and worse lattice oxygen stability during cycling, resulting in capacity attenuation and kinetics hysteresis. Herein, a Li2SiO3-coated Li(Ni0.95Co0.04Mn0.01)0.99B0.01O2 ultrahigh-Ni cathode that well-addresses all the above issues, which is also the first time to realize the real doping of B ions is demonstrated. The as-obtained cathode delivers a reversible capacity of up to 237.4 mAh g-1 (924 Wh kg-1 cathode) and a superior capacity retention of 84.2% after 500 cycles at 1C in pouch-type full-cells. Advanced characterizations and calculations verify that the boron-doping is existed in terms of 3-coordinate and 4-coordinate configurations and their high electrochemical reversibility during de-/lithiation, which greatly stabilizes oxygen anions and impedes Ni-ion migration to Li layer. Furthermore, the B-doping engineers the primary particle microstructure for better relaxing the lattice strain and accelerating Li-ion diffusion. This work advances the energy density of cathode materials into the domain of above 900 Wh kg-1, and the concept will inspire more intensive study on ultrahigh-Ni cathodes.

A Plastic-Crystal Electrolyte Layer Promotes Interfacial Stability of Ni-Rich Oxide Cathode in Li6PS5Cl-Based All-Solid-State Rechargeable Li Batteries

Unfavorable parasitic reactions between the Ni-rich layered oxide cathode and the sulfide solid electrolyte have plagued the realization of all-solid-state rechargeable Li batteries. The accumulation of inactive by-products (P2Sx, S, POx n- and SOx n-) at the cathode-sulfide interface impedes fast Li-ion transfer, which accounts for sluggish reaction kinetics and significant loss of cathode capacity. Herein, we proposed an easily scalable approach to stabilize the cathode electrochemistry via coating the cathode particles by a uniform, Li+-conductive plastic-crystal electrolyte nanolayer on their surface. The electrolyte, which simply consists of succinonitrile and Li bis(trifluoromethanesulphonyl)imide, serves as an interfacial buffer to effectively suppress the adverse phase transition in highly delithiated cathode materials, and the loss of lattice oxygen and generation of inactive oxygenated by-products at the cathode-sulfide interface. Consequently, an all-solid-state rechargeable Li battery with the modified cathode delivers high specific capacities of 168 mAh g-1 at 0.1 C and a high capacity retention >80 % after 100 cycles. Our work sheds new light on rational design of electrode-electrolyte interface for the next-generation high-energy batteries.

Interface Degradation of LaCl3-Based Solid Electrolytes Coupled with Ultrahigh-Nickel Cathodes

Despite competitive compatibility with high-nickel cathodes, chloride solid electrolytes (SEs) still experience inevitable side reactions at the cathode/SE interface, causing capacity decay in all-solid-state lithium batteries (ASSLBs) during cycling. Herein, a three-electrode ASSLB testing device is developed to comprehensively reveal the interface failure mechanisms of the ultrahigh-nickel LiNi0.92Co0.05Mn0.03O2 (NCM92) cathode paired with LaCl3-based chloride SE Li0.447La0.475Zr0.059Ta0.179Cl3 (LLZTC). Distribution of relaxation time (DRT) analysis clearly shows the ASSLB degradation accompanied by a significant NCM92/LLZTC interface impedance increase, which becomes more pronounced at the higher cutoff charging voltage of 4.8 V vs Li+/Li. Furthermore, time-of-flight secondary ion mass spectrometry (ToF-SIMS) and focused ion beam scanning electron microscopy (FIB-SEM) analysis also confirm the deterioration arising from active lattice oxygen and loss of physical contact at the NCM92/LLZTC interface. These findings reveal both electrochemical degradation and physical contact failure at the cathode/SE interface as key causes of the ASSLBs' capacity decay.

Toward High-Performance Li-Rich Mn-Based Layered Cathodes: A Review on Surface Modifications

Lithium-rich manganese-based layered oxides (LRMOs) have received attention from both the academic and the industrial communities in recent years due to their high specific capacity (theoretical capacity ≥250 mAh g-1), low cost, and excellent processability. However, the large-scale applications of these materials still face unstable surface/interface structures, unsatisfactory cycling/rate performance, severe voltage decay, etc. Recently, solid evidence has shown that lattice oxygen in LRMOs easily moves and escapes from the particle surface, which inspires significant efforts on stabilizing the surface/interfacial structures of LRMOs. In this review, the main issues associated with the surface of LRMOs together with the recent advances in surface modifications are outlined. The critical role of outside-in surface decoration at both atomic and mesoscopic scales with an emphasis on surface coating, surface doping, surface structural reconstructions, and multiple-strategy co-modifications is discussed. Finally, the future development and commercialization of LRMOs are prospected. Looking forward, the optimal surface modifications of LRMOs may lead to a low-cost and sustainable next-generation high-performance battery technology.

Dual Ionic Pathways in Semi-Solid Electrolyte based on Binary Metal-Organic Frameworks Enable Stable Operation of Li-Metal Batteries at Extremely High Temperatures

The rapid development of the electronics market necessitates energy storage devices characterized by high energy density and capacity, alongside the ability to maintain stable and safe operation under harsh conditions, particularly elevated temperatures. In this study, a semi-solid-state electrolyte (SSSE) for Li-metal batteries (LMB) is synthesized by integrating metal-organic frameworks (MOFs) as host materials featuring a hierarchical pore structure. A trace amount of liquid electrolyte (LE) is entrapped within these pores through electrochemical activation. These findings demonstrate that this structure exhibits outstanding properties, including remarkably high thermal stability, an extended electrochemical window (5.25 V vs Li/Li+), and robust lithium-ion conductivity (2.04 × 10-4 S cm-1), owing to the synergistic effect of the hierarchical MOF pores facilitating the storage and transport of Li ions. The Li//LiFePO4 cell incorporating prepared SSSE shows excellent capacity retention, retaining 97% (162.8 mAh g-1) of their initial capacity after 100 cycles at 1 C rate at an extremely high temperature of 95 °C. It is believed that this study not only advances the understanding of ion transport in MOF-based SSSE but also significantly contributes to the development of LMB capable of stable and safe operation even under extremely high temperatures.

Lanthanum doping and surface Li3BO3 passivating layer enabling 4.8 V nickel-rich layered oxide cathodes toward high energy lithium-ion batteries

Single crystalline Ni-rich layered oxide cathodes show high energy density and low cost, have been regarded as one of the most promising candidates for next generation lithium-ion batteries (LIBs). Extending the cycling voltage window will significantly improve the energy density, however, suffers from bulk structural and interfacial chemistry degradation, leading to rapidly cycle performance deterioration. Here, we propose a dual-modification strategy to synthesize La doping and Li3BO3 (LBO) coating layers modified LiNi0.8Co0.1Mn0.1O2 (NCM811) by a facile one-step heating treatment processing. In-situ EIS and XRD, ex-situ XPS techniques are applied to demonstrate that the La diffused amorphous domains and Li3BO3 passivating layers dampen the lattice distortion, enhance the interfacial chemistry behavior as well as lithium ion transportation kinetics. Specifically, surface La doping amorphous domains successfully suppress the intense lattice stress and volume changes induced by the phase transitions during lithiation/delithiation, thus avoiding the intergranular crack and enhancing the mechanical stability of the material. Moreover, the LBO layer formed by the consumption of residual lithium prevents successive parasitic reactions at the interface as well as provides rapid Li-ion diffusion channels. Furthermore, the coating layer also diminishes the residual lithium compounds, increasing the atmosphere stability and safety of LIBs. Consequently, the La doping and LBO coating NCM811 exhibits an exceptional initial specific capacity (230.6 mAh/g) at 0.5C under a high cutoff voltage of 4.8 V, and a 73.8 % capacity retention following 100 cycles. In addition, a superior specific capacity of 133.8 mAh/g is provided even at a high current density (4C). Our work paves a promising road to tackle the integral structure deterioration and interfacial instability of Ni-rich cathodes.

Amorphous AlOCl Compounds Enabling Nanocrystalline LiCl with Abnormally High Ionic Conductivity

LiCl is a promising solid electrolyte, providing it possesses high ionic conductivity. Numerous efforts have been made to enhance its ionic conductivity through aliovalent doping. However, aliovalent substitution changes the intrinsic structure of LiCl, compromising its cost-effectiveness and electrochemical stability. Here, we report nanocrystalline LiCl embedded in amorphous AlOCl compounds with a heterogeneous structure to enhance its ionic conductivity. Nanocrystallization enlarges the LiCl unit cell, while amorphization facilitates interfacial ion transport. As a result, the amorphous AlOCl-modified LiCl nanocrystal (AlOCl-nanoLiCl) demonstrates a high ionic conductivity of 1.02 mS cm-1, which is 5 orders of magnitude higher than that of LiCl. Additionally, it exhibits high oxidative stability, low cost ($19.87 US kg-1), and low Young's modulus (2-3 GPa). When AlOCl-nanoLiCl is coupled with Li-rich cathodes (Li1.17Mn0.55Ni0.24Co0.05O2, 4.8 V vs Li+/Li), all-solid-state batteries exhibit remarkable long-term cycling stability (>1000 cycles). This work presents a novel strategy to enhance the ionic conductivity of alkaline chlorides without compromising their intrinsic advantages.

Flow-electrode capacitive separation of organic acid products and recovery of alkali cations after acidic CO2 electrolysis

Acidic CO2 electrolysis, enhanced by the introduction of alkali cations, presents a strategic approach for improving carbon efficiency compared to processes conducted in neutral and alkaline environments. However, a significant challenge arises from the dissolution of both organic acids and alkali cations in a strongly acidic feed stream, resulting in a considerable energy penalty for downstream separation. In this study, we investigate the feasibility of using flow-electrode capacitive deionization (FCDI) technology to separate organic acids and recover alkali cations from a strongly acidic feed stream (pH ~ 1). We show that organic acids, such as formic acid and acetic acid, are retained in molecular form in the separation chamber, achieving a rejection rate of over 90% under all conditions. Alkali cations, such as K+ and Cs+, migrate to the cathode chamber in ionic form, with their removal and recovery significantly influenced by their concentration and the pH of the feed stream, but responding differently to the types and concentrations of organic acids. The energy consumption for the removal and recovery of K+ is 4 to 8 times higher than for Cs+, and the charge efficiency is significantly influenced by the types of organic acid products and alkali cations. We conduct a series of electrochemical measurements and analyze the impedance spectroscopy, identifying that hindered mass transfer governed the electrode process. Our findings underscore the potential of FCDI as an advanced downstream separation technology for acidic electrocatalysis processes.

High-Performance Sheet-Type Sulfide All-Solid-State Batteries Enabled by Dual-Function Li4.4Si Alloy-Modified Nano Silicon Anodes

The silicon-based anodes are one of the promising anodes to achieve the high energy density of all-solid-state batteries (ASSBs). Nano silicon (nSi) is considered as a suitable anode material for assembling sheet-type sulfide ASSBs using thin free-standing Li6PS5Cl (LPSC) membrane without causing short circuit. However, nSi anodes face a significant challenge in terms of rapid capacity degradation during cycling. To address this issue, dual-function Li4.4Si modified nSi anode sheets are developed, in which Li4.4Si serves a dual role by not only providing additional Li+ but also stabilizing the anode structure with its low Young's modulus upon cycling. Sheet-type ASSBs equipped with the Li4.4Si modified nSi anode, thin LPSC membrane, and LiNi0.83Co0.11Mn0.06O2 (NCM811) cathode demonstrate exceptional cycle stability, with a capacity retention of 96.16% at 0.5 C (1.18 mA cm-2) after 100 cycles and maintain stability for 400 cycles. Furthermore, a remarkable cell-level energy density of 303.9 Wh kg-1 is achieved at a high loading of 5.22 mAh cm-2, representing a leading level of sulfide ASSBs using electrolyte membranes at room temperature. Consequently, the chemically stable slurry process implemented in the fabrication of Li4.4Si-modified nSi anode sheet paves the way for scalable applications of high-performance sulfide ASSBs.

Bulk/Interfacial Structure Design of Li-Rich Mn-Based Cathodes for All-Solid-State Lithium Batteries

Li-rich Mn-based cathode materials (LRMO) are promising for enhancing energy density of all-solid-state batteries (ASSBs). Nonetheless, the development of efficient Li+/e- pathways is hindered by the poor electrical conductivity of LRMO cathodes and their incompatible interfaces with solid electrolytes (SEs). Herein, we propose a strategy of in-situ bulk/interfacial structure design to construct fast and stable Li+/e- pathways by introducing Li2WO4, which reduces the energy barrier for Li+ migration and enhances the stability of the surface oxygen structure. The reversibility of oxygen redox was improved, and the voltage decay of the LRMO cathode was addressed significantly. As a result, the bulk structure of the LRMO cathodes and the high-voltage solid-solid interfacial stability are improved. Therefore, the ASSBs achieve a high areal capacity (∼3.15 mAh/cm2) and outstanding cycle stability of ≥1200 cycles with 84.1% capacity retention at 1 C at 25 °C. This study offers new insights into LRMO cathode design strategies for ASSBs, focusing on ultrastable high-voltage interfaces and high-loading composite electrodes.

Interpenetrating LiB/Li3BN2 phases enabling stable composite lithium metal anode

Host-less lithium metal anode generally suffers from large volume changes and serious dendrite growth during cycling, which poses challenges for its practical application. Interpenetrating phase composites with continuous architectures offer a solution to enhance mechanical properties of materials. Herein, a robust composite Li anode (LBN) material is fabricated through the metallurgical reaction between Li and hexagonal boron nitride (h-BN) with the formation of interpenetrating LiB/Li3BN2 phases. As LiB fibers are anchored by Li3BN2 granules, the collapse and slippage of LiB fibers are suppressed whilst the mechanical strength and structural stability of LBN are reinforced. By rolling, ultrathin (15 μm), freestanding, and electrochemically stable LBN foil can be obtained. The LBN anode exhibits a high average Coulombic efficiency of 99.69% (1 mA cm-2, 3 mAh cm-2) and a long lifespan of 2500 h (1 mA cm-2, 1 mAh cm-2). Notably, the LiCoO2 (with double-sided load 40 mg cm-2)|LBN pouch cell can operate over 450 cycles with a capacity retention of 90.1%. The exceptional cycling stability of LBN can be ascribed to the interpenetrating reinforcement architectures and synergistic electronic/ionic conductivity of the LiB/Li3BN2 dual-lithiophilic-phases. This work provides a new methodology for thin Li strip processing and reinforced-architecture design, with implications beyond battery applications.

Constructing An Oxyhalide Interface for 4.8 V-Tolerant High-Nickel Cathodes in All-Solid-State Lithium-Ion Batteries

All-solid-state lithium batteries (ASSBs) have received increasing attentions as one promising candidate for the next-generation energy storage devices. Among various solid electrolytes, sulfide-based ASSBs combined with layered oxide cathodes have emerged due to the high energy density and safety performance, even at high-voltage conditions. However, the interface compatibility issues remain to be solved at the interface between the oxide cathode and sulfide electrolyte. To circumvent this issue, we propose a simple but effective approach to magic the adverse surface alkali into a uniform oxyhalide coating on LiNi0.8Co0.1Mn0.1O2 (NCM811) via a controllable gas-solid reaction. Due to the enhancement of the close contact at interface, the ASSBs exhibit improved kinetic performance across a broad temperature range, especially at the freezing point. Besides, owing to the high-voltage tolerance of the protective layer, ASSBs demonstrate excellent cyclic stability under high cutoff voltages (500 cycles~94.0 % at 4.5 V, 200 cycles~80.4 % at 4.8 V). This work provides insights into using a high voltage stable oxyhalide coating strategy to enhance the development of high energy density ASSBs.

Highly-Solvating Electrolyte Enables Mechanically Stable and Inorganic-Rich Cathode Electrolyte Interphase for High-Performing Potassium-Ion Batteries

Cathode-electrolyte interphase (CEI) is crucial for the reversibility of rechargeable batteries, yet receives less attention compared to solid-electrolyte interphase (SEI). The prevalent weakly-solvating electrolyte is usually proposed from the standing point of obtaining robust SEI, however, the resultant weak ion-solvent interaction gives rise to excessive free solvents and forms thick CEI with high kinetic barriers, which is disadvantageous for interfacial stability at the high working voltage. Herein, a highly-solvating electrolyte is reported to immobilize free solvents by generating stable ternary complexes and facilitate the growth of homogeneous and ultrathin CEI to boost the electrochemical performances of potassium-ion batteries (PIBs). Through time-of-flight secondary ion mass spectrometry and cryogenic transmission electron microscopy, It is revealed that the deliberately coordinated complexes are the key to forming mechanically stable and inorganic-rich CEI with superior diffusion kinetics for high-performing PIBs. Coupling with a K0.5MnO2 cathode and a soft carbon (SC) anode, a high energy density (202.3 Wh kg-1) is achieved with an exceptional cycle lifespan (92.5% capacity retention after 500 cycles) in a SC||K0.5MnO2 full cell, setting new performance benchmarks for PIBs.

Ni-Rich Layered Oxide Cathodes/Sulfide Electrolyte Interface in Solid-State Lithium Battery

Because of the high specific capacity and low cost, Ni-rich layered oxide (NRLO) cathodes are one of the most promising cathode candidates for the next high-energy-density lithium-ion batteries. However, they face structure and interface instability challenges, especially the battery safety risk caused by using an intrinsic flammable organic liquid electrolyte. In this regard, a solid electrolyte with high safety is of great significance to promote the development of energy storage. Among them, sulfide electrolytes are considered to be the most potential substitutes for liquid electrolytes because of their high ionic conductivity and good processing properties. Nevertheless, the interfacial incompatibility between the sulfide electrolyte and NRLO cathode is the critical challenge for high-performance sulfide all-solid-state lithium batteries (ASSLBs). In this review, we summarize the problems of the Ni-rich cathode/sulfide solid electrolyte interface and the strategies to improve the interface stability. On the basis of these insights, we highlight the scientific problems and technological challenges that need to be resolved urgently and propose several potential directions to further improve the interface stability. The objective of this study is to provide a comprehensive understanding and insightful recommendations for the enhancement of the sulfide ASSLBs with NRLO cathode.

Defect-Driven Configurational Entropy in the High-Entropy Oxide Li1.5MO3-δ

Layered lithiated oxides are promising materials for next generation Li-ion battery cathode materials; however, instability during cycling results in poor performance over time compared to the high capacities theoretically possible with these materials. Here we report the characterizations of a Li1.47Mn0.57Al0.13Fe0.095Co0.105Ni0.095O2.49 high-entropy layered oxide (HELO) with the Li2MO3 structure where M = Mn, Al, Fe, Co, and Ni. Using electron microscopy and X-ray spectroscopy, we identify a homogeneous Li2MO3 structure stabilized by the entropic contribution of oxygen vacancies. This defect-driven entropy would not be attainable in the LiMO2 structure sometimes observed in similar materials as a secondary phase owing to the presence of fewer O sites and a 3+ oxidation state for the metal site; instead, a Li2-γMO3-δ is produced. Beyond Li2MO3, this defect-driven entropy approach to stabilizing novel compositions and phases can be applied to a wide array of future cathode materials including spinel and rock salt structures.

Influence Mechanism of Interfacial Oxidation of Li3YCl6 Solid Electrolyte on Reduction Potential

Halide-based solid electrolytes are promising candidates for all solid-state lithium-ion batteries (ASSLBs) due to their high ionic conductivity, wide electrochemical window, and excellent chemical stability with cathode materials. However, when tested in practice, their intrinsic electrochemical stability windows do not well match the conditions for stable operation of ASSBs. Existing literature reports halide-based ASSBs that still operate well outside the electrochemical stability window, while ASSBs that do not operate within the window are not well studied or the studies are based on the cathode material interface. In this study, we aim to elucidate the mechanism behind all-solid-state battery failure by investigating how the reduction potential of Li3YCl6 solid-state electrolyte itself changes under overcharging conditions. Our findings demonstrate that in Li-In|Li3YCl6|Li3YCl6-C half-cells during the first state of charge, Cl ions participate in charge compensation, resulting in a depletion of ligands. This phenomenon significantly affects the reduction potential of Y3+, causing it to be reduced to Y2Cl3 and ultimately to Y0 at conditions far exceeding its actual reduction potential. Furthermore, we analyze the interfacial impedance induced by this process and propose a novel perspective on battery failure.

From Liquid to Solid-State Batteries: Li-Rich Mn-Based Layered Oxides as Emerging Cathodes with High Energy Density

Li-rich Mn-based (LRMO) cathode materials have attracted widespread attention due to their high specific capacity, energy density, and cost-effectiveness. However, challenges such as poor cycling stability, voltage deca,y and oxygen escape limit their commercial application in liquid Li-ion batteries. Consequently, there is a growing interest in the development of safe and resilient all-solid-state batteries (ASSBs), driven by their remarkable safety features and superior energy density. ASSBs based on LRMO cathodes offer distinct advantages over conventional liquid Li-ion batteries, including long-term cycle stability, thermal and wider electrochemical windows stability, as well as the prevention of transition metal dissolution. This review aims to recapitulate the challenges and fundamental understanding associated with the application of LRMO cathodes in ASSBs. Additionally, it proposes the mechanisms of interfacial mechanical and chemical instability, introduces noteworthy strategies to enhance oxygen redox reversibility, enhances high-voltage interfacial stability, and optimizes Li+ transfer kinetics. Furthermore, it suggests potential research approaches to facilitate the large-scale implementation of LRMO cathodes in ASSBs.

Formulating Local Environment of Oxygen Mitigates Voltage Hysteresis in Li-Rich Materials

Li-rich cathode materials have emerged as one of the most prospective options for Li-ion batteries owing to their remarkable energy density (>900 Wh kg-1). However, voltage hysteresis during charge and discharge process lowers the energy conversion efficiency, which hinders their application in practical devices. Herein, the fundamental reason for voltage hysteresis through investigating the O redox behavior under different (de)lithiation states is unveiled and it is successfully addressed by formulating the local environment of O2-. In Li-rich Mn-based materials, it is confirmed that there exists reaction activity of oxygen ions at low discharge voltage (<3.6 V) in the presence of TM-TM-Li ordered arrangement, generating massive amount of voltage hysteresis and resulting in a decreased energy efficiency (80.95%). Moreover, in the case where Li 2b sites are numerously occupied by TM ions, the local environment of O2- evolves, the reactivity of oxygen ions at low voltage is significantly inhibited, thus giving rise to the large energy conversion efficiency (89.07%). This study reveals the structure-activity relationship between the local environment around O2- and voltage hysteresis, which provides guidance in designing next-generation high-performance cathode materials.

An ultralight, pulverization-free integrated anode toward lithium-less lithium metal batteries

The high-capacity advantage of lithium metal anode was compromised by common use of copper as the collector. Furthermore, lithium pulverization associated with "dead" Li accumulation and electrode cracking deteriorates the long-term cyclability of lithium metal batteries, especially under realistic test conditions. Here, we report an ultralight, integrated anode of polyimide-Ag/Li with dual anti-pulverization functionality. The silver layer was initially chemically bonded to the polyimide surface and then spontaneously diffused in Li solid solution and self-evolved into a fully lithiophilic Li-Ag phase, mitigating dendrites growth or dead Li. Further, the strong van der Waals interaction between the bottommost Li-Ag and polyimide affords electrode structural integrity and electrical continuity, thus circumventing electrode pulverization. Compared to the cutting-edge anode-free cells, the batteries pairing LiNi0.8Mn0.1Co0.1O2 with polyimide-Ag/Li afford a nearly 10% increase in specific energy, with safer characteristics and better cycling stability under realistic conditions of 1× excess Li and high areal-loading cathode (4 milliampere hour per square centimeter).

In Situ Construction of LiF-Li3N-Rich Interface Contributed to Fast Ion Diffusion in All-Solid-State Lithium-Sulfur Batteries

All-solid-state lithium-sulfur batteries (ASSLSBs) have attracted wide attention due to their ultrahigh theoretical energy density and the ability of completely avoiding the shuttle effect. However, the further development of ASSLSBs is limited by the poor kinetic properties of the solid electrode interface. It remains a great challenge to achieve good kinetic properties, by common strategies to substitute sulfur-transition metal and organosulfur composites for sulfur without reducing the specific capacity of ASSLSBs. In this study, a sulfur-(Ketjen Black)-(bistrifluoromethanesulfonimide lithium salt) (S-KB-LiTFSI) composite is constructed by introducing LiTFSI into the S-KB composite. The initial discharge capacity reaches up to 1483 mA h g-1, benefited from the improved ionic conductivity and diffusion kinetics of the S-KB-LiTFSI composite, where numerous LiF interphases with a Li3N component are in situ formed during cycling. Combined with DFT calculations, it is found that the migration barriers of LiF and Li3N are much smaller than that of the Li6PS5Cl solid electrolyte. The fast ionic conductors of LiF and Li3N not only enhance the Li+ transfer efficiency but also improve the interfacial stability. Therefore, the assembled ASSLSBs operate stably for 600 cycles at 200 mA g-1, and this study provides an effective strategy for the further development of ASSLSBs.

Towards Efficient Polymeric Binders for Transition Metal Oxides-based Li-ion Battery Cathodes

Transition metal oxide cathodes (TMOCs) such as LiNi0.8Mn0.1Co0.1O2 and LiMn1.5Ni0.5O4 have been widely employed in Li-ion batteries (LIBs) owing to superior operating voltages, high reversible capacities and relatively low cost. Nevertheless, despite significant advancements in practical application, TMOC-based LIBs face great challenges such as transition metal dissolution and volume expansion during cycling, which jeopardizes the future advance of high-voltage TMOCs. As a critical component of cathode, polymeric binder acts as a crucial part in maintaining the mechanical and ion/electron conductive integrity between active particles, carbon additives, and the aluminum collector, hence minimizing cathode pulverization during battery cycling. Moreover, Polymeric binder with specialized functions is thought to offer a new solution to enhancing the electrochemical stability of the TMOCs. Therefore, this review aims at providing a comprehensive summary of the ideal requirements, design strategies and recent progress of polymeric binders for TMOCs. Future design perspectives and promising research technologies for advanced binders for high-voltage TMOCs are introduced.

Promoting high-voltage stability through local lattice distortion of halide solid electrolytes

Stable solid electrolytes are essential to high-safety and high-energy-density lithium batteries, especially for applications with high-voltage cathodes. In such conditions, solid electrolytes may experience severe oxidation, decomposition, and deactivation during charging at high voltages, leading to inadequate cycling performance and even cell failure. Here, we address the high-voltage limitation of halide solid electrolytes by introducing local lattice distortion to confine the distribution of Cl-, which effectively curbs kinetics of their oxidation. The confinement is realized by substituting In with multiple elements in Li3InCl6 to give a high-entropy Li2.75Y0.16Er0.16Yb0.16In0.25Zr0.25Cl6. Meanwhile, the lattice distortion promotes longer Li-Cl bonds, facilitating favorable activation of Li+. Our results show that this high-entropy halide electrolyte boosts the cycle stability of all-solid-state battery by 250% improvement over 500 cycles. In particular, the cell provides a higher discharge capacity of 185 mAh g-1 by increasing the charge cut-off voltage to 4.6 V at a small current rate of 0.2 C, which is more challenging to electrolytes|cathode stability. These findings deepen our understanding of high-entropy materials, advancing their use in energy-related applications.

Metal-Free Eutectic Electrolyte with Weak Hydrogen Bonds for High-Rate and Ultra-Stable Ammonium-Ion Batteries

As the need for sustainable battery chemistry grows, non-metallic ammonium ion (NH4 + ) batteries are receiving considerable attention because of their unique properties, such as low cost, nontoxicity, and environmental sustainability. In this study, the solvation interactions between NH4 + and solvents are elucidated and design principles for NH4 + weakly solvated electrolytes are proposed. Given that hydrogen bond interactions dominate the solvation of NH4 + and solvents, the strength of the solvent's electrostatic potential directly determines the strength of its solvating power. As a proof of concept, succinonitrile with relatively weak electronegativity is selected to construct a metal-free eutectic electrolyte (MEE). As expected, this MEE is able to significantly broaden the electrochemical stability window and reduce the solvent binding energy in the solvation shell, which leads to a lower desolvation energy barrier and a fast charge transfer process. As a result, the as-constructed NH4 -ion batteries exhibit superior reversible rate capability (energy density of 65 Wh kg-1 total active mass at 600 W kg-1 ) and unprecedent long-term cycling performance (retention of 90.2% after 1000 cycles at 1.0 A g-1 ). The proposed methodology for constructing weakly hydrogen bonded electrolytes will provide guidelines for implementing high-rate and ultra-stable NH4 + -based energy storage systems.

Suppressing Surface Ligand-to-Metal Charge Transfer toward Stable High-Voltage LiCoO2

Increasing the charging cutoff voltage is a viable approach to push the energy density limits of LiCoO2 and meet the requirements of the rapid development of 3C electronics. However, an irreversible oxygen redox is readily triggered by the high charging voltage, which severely restricts practical applications of high-voltage LiCoO2. In this study, we propose a modification strategy via suppressing surface ligand-to-metal charge transfer to inhibit the oxygen redox-induced structure instability. A d0 electronic structure Zr4+ is selected as the charge transfer insulator and successfully doped into the surface lattice of LiCoO2. Using a combination of theoretical calculations, ex situ X-ray absorption spectra, and in situ differential electrochemical mass spectrometry analysis, our results show that the modified LiCoO2 exhibits suppressed oxygen redox activity and stable redox electrochemistry. As a result, it demonstrates a robust long-cycle lattice structure with a practically eliminated voltage decay (0.17 mV/cycle) and an excellent capacity retention of 89.4% after 100 cycles at 4.6 V. More broadly, this work provides a new perspective on suppressing the oxygen redox activity through modulating surface ligand-to-metal charge transfer for achieving a stable high-voltage ion storage structure.

Achieving the High Capacity and High Stability of Li-Rich Oxide Cathode in Garnet-Based Solid-State Battery

Solid-state batteries (SSBs) based on Li-rich Mn-based oxide (LRMO) cathodes attract much attention because of their high energy density as well as high safety. But their development was seriously hindered by the interfacial instability and inferior electrochemical performance. Herein, we design a three-dimensional foam-structured GaN-Li composite anode and successfully construct a high-performance SSB based on Co-free Li1.2 Ni0.2 Mn0.6 O2 cathode and Li6.5 La3 Zr1.5 Ta0.5 O12 (LLZTO) solid electrolyte. The interfacial resistance is considerably reduced to only 1.53 Ω cm2 and the assembled Li symmetric cell is stably cycled more than 10,000 h at 0.1-0.2 mA cm-2 . The full battery shows a high initial capacity of 245 mAh g-1 at 0.1 C and does not show any capacity degradation after 200 cycles at 0.2 C (≈100 %). The voltage decay is well suppressed and it is significantly decreased from 2.96 mV/cycle to only 0.66 mV/cycle. The SSB also shows a very high rate capability (≈170 mAh g-1 at 1 C) comparable to a liquid electrolyte-based battery. Moreover, the oxygen anion redox (OAR) reversibility of LRMO in SSB is much higher than that in liquid electrolyte-based cells. This study offers a distinct strategy for constructing high-performance LRMO-based SSBs and sheds light on the development and application of high-energy density SSBs.

Sulfur-Assisted Surface Modification of Lithium-Rich Manganese-Based Oxide toward High Anionic Redox Reversibility

Energy storage via anionic redox provides extra capacity for lithium-rich manganese-based oxide cathodes at high voltage but causes gradual structural collapse and irreversible capacity loss with generation of On - (0 ≤ n < 2) species upon deep oxidation. Herein, the stability and reversibility of anionic redox reactions are enhanced by a simple sulfur-assisted surface modification method, which not only modulates the material's energy band allowing feasible electron release from both bonding and antibonding bands, but also traps the escaping On - via an as-constructed SnS2- x - σ Oy coating layer and return them to the host lattice upon discharge. The regulation of anionic redox inhibits the irreversible structural transformation and parasitic reactions, maintaining the specific capacity retention of as-modified cathode up to 94% after 200 cycles at 100 mA g-1 , along with outstanding voltage stability. The reported strategy incorporating energy band modulation and oxygen trapping is promising for the design and advancement of other cathodes storing energy through anion redox.

Toward Ultrastable Metal Anode/Li6PS5Cl Interface via an Interlayer as Li Reservoir

All-solid-state sulfide-based Li metal batteries are promising candidates for energy storage systems. However, thorny issues associated with undesired reactions and contact failure at the anode interface hinder their commercialization. Herein, an indium foil was endowed with a formed interlayer whose surface film is enriched with LiF and LiIn phases via a feasible prelithiation route. The lithiated alloy of the interlayer can regulate Li+ flux and charge distribution as a Li reservoir, benefiting uniform Li deposition. Meanwhile, it can suppress the reductive decomposition of the Li6PS5Cl electrolyte and maintain sufficient solid-solid contact. In situ impedance spectra reveal that constant interface impedance and fast charge transfer are realized by the interlayer. Further, long-term Li stripping/plating over 2000 h at 2.55 mA cm-2 is demonstrated by this anode. All-solid-state cells employing a LiCoO2 cathode and the Pre In anode can work for over 700 cycles with a capacity retention of 96.15% at 0.5 C.

A prototype of dual-ion conductor for all-solid-state lithium batteries

All-solid-state batteries (ASSBs) represent a promising battery strategy to achieve high energy density with great safety. However, inadequate kinetic property and poor interfacial compatibility remain great challenges, which impede their practical application. A prototype of dual-ion conductor of Li+ synchronized with Cu+ unlocks a four-electron redox reaction with high reversibility and fast kinetics. As a result, the constructed ASSB exhibited a high reversible capacity of 603.0 mA·hour g-1 and an excellent cycling retention of 93.2% over 1500 cycles. Moreover, because of the ion highway connecting active materials and catholytes constructed by dual-ion conductor, remarkable temperature tolerance (-60°C) and excellent rate performance (231.6 mA·hour g-1 at 20 mA cm-2) were achieved. The superior electrochemical performance can be ascribed to the migration pathway with small energy barrier and low tortuosity once the Cu+ introduced into Li6PS5Cl. This work creates a unique perspective of ASSBs with dual-ion conducting strategy, thus inspiring a potential developing strategy of state-of-the-art ASSBs.