Lithium-rich oxide cathodes present high specific capacities (> 250mAhg-1) and wide operating voltage windows (2.0-4.8V), making them promising candidates for next-generation high-energy batteries. Their practical deployment, however, is limited by sluggish ion transport kinetics that arise from inherent structural constraints, including confined two-dimensional diffusion channels, transition metal migration, and local lattice distortions. These structural perturbations narrow Li+ pathways, intensify cation mixing, and generate localized strain fields, collectively increasing the Li+ migration energy barrier. To facilitate the rational design of fast-kinetic lithium-rich oxides through intrinsic structural optimization, a comprehensive elucidation of the structure-diffusion interplay is presented, with emphasis on the roles of lattice distortion and oxygen redox chemistry in modulating Li+ pathways and associated energy barriers. Structural design strategies that aim to improve ionic diffusivity are systematically evaluated, including interface engineering, morphology-directed design, and the modulation of redox chemistry. Advanced operando characterization techniques that capture dynamic structural and chemical evolution are also described as essential tools for guiding precise structure-performance analysis. The mechanistic insights and integrated analytical approaches summarized in this review establish a robust conceptual foundation for engineering lithium-rich oxides with enhanced ion transport kinetics, thereby supporting the advancement of next-generation high-power battery technologies.

The practical implementation of pure lithium nickelate (LiNiO2) as a high-capacity cathode for lithium-ion batteries is obstructed by detrimental H2–H3 phase transitions and cation mixing, which cause significant capacity fading. To address these challenges, we investigated the structural and electrochemical properties of LiNiO2 modified by magnesium (Mg) doping and tungsten (W) passivation. Herein, we report that the interplay of 2 mol % Mg doping and 0.5 mol % W passivation successfully mitigates both cation disorder and gliding-induced degradation. The optimized cathode delivers a remarkable capacity retention of 88.1% after 100 cycles at 1 C. The performance enhancement originates from the cooperative mechanism in which Mg doping suppresses Li/Ni cation mixing within the bulk lattice, whereas the W-based surface passivation layer alleviates anisotropic strain during cycling. The dual-modification strategy at both the bulk and surface provides a robust pathway to stabilize LiNiO2 and promote its practical implementation in next-generation high-energy lithium-ion batteries.

High-nickel cobalt-free cathodes are deemed promising candidates for next-generation lithium-ion batteries owing to their superior energy density, cost-effectiveness, and environmental benignity. However, their practical implementation is hindered by inherent structural instability and rapid capacity degradation. Herein, we develop a Mo/F cation-anion modified single-crystalline LiNi0.8Mn0.2O2 cathode material (SC-MFNM) via a designed facile high-temperature solid-state synthesis route. During high-temperature calcination, the lattice strain induced by structural transition promotes the outward migration of Mo6+ ions from the Ni-rich core to the surface region, leading to lattice reorganization and expansion of surface interplanar spacing. The resultant lattice gradient facilitates rapid ion transport from the electrolyte through the expanded surface lattice, while the compact inner lattice enables ordered ion insertion. Consequently, this structure effectively mitigates irreversible phase transitions and stabilizes the layered framework by suppressing cation mixing, while simultaneously preserving the high specific capacity to the Ni-rich layer core, offering an approach to improve the structural and electrochemical stability of the Ni-rich cathode. Benefiting from the structural merits, the SC-MFNM cathode exhibits exceptional cycling stability, delivering a reversible capacity of 164.9 mAh g-1 after 300 cycles at 1.0 C compared with the lower capacity of 51.5 mAh g-1 from the polycrystalline cathode. This work demonstrates the importance of lattice regulation and structural evolution in improving the structural and electrochemical stability of high-nickel cobalt-free cathodes, contributing significantly to the development of high-energy-density lithium-ion batteries with long-term cycling durability.

Lithium-ion batteries (LIBs) are the dominant technology for electrochemical energy storage. However, the surging demand for LIBs has intensified concerns over cobalt (Co) scarcity, ethical sourcing, and cost volatility. To overcome these challenges, Co-free Ni-rich layered cathode materials have attracted growing attention. This review provides a comprehensive overview of recent developments in their preparation processes and performance optimization. The dual role of Co in conventional cathodes is first clarified: Co mitigates Li/Ni cation disorder but also induces lattice distortion, oxygen release, and microcrack formation. Eliminating Co, however, aggravates Rich-Ni-related issues such as structural phase transitions and severe Li/Ni cation mixing, which compromise structural and electrochemical stability. Recent progress in addressing these challenges is summarized, focusing on composition regulation, surface engineering, and structural design strategies. Preparation methodologies are discussed in detail, including wet chemical approaches that enable precise control over morphology and composition control, and solid-state techniques that offer scalability for industrial application. Optimized Co-free Ni-rich layered materials exhibit enhanced capacity retention, structural integrity, and thermal stability. Finally, the review highlights future research directions toward simplified processes, synergistic multi-technology coupling, and data-driven design to promote the commercialization of Co-free Ni-rich layered oxide cathodes for electric vehicles and large-scale energy storage systems.

LiNi0.6Mn0.4O2 (NM64), a cobalt-free cathode material with high theoretical capacity and approximately 30% lower cost than commercial LiNi0.6Co0.2Mn0.2O2 (NCM622), is a promising cathode for lithium-ion batteries. However, structural instability and sluggish kinetics limit its potential for large-scale commercial applications. To address these challenges, we propose a dual-function strategy that simultaneously enhances ion transport by reducing cation mixing and dissipates stress via elongated primary grains in oxygen-calcined NM64 (O-NM64), achieving superior robustness. Consequently, the O-NM64 exhibits a high specific capacity of 201.6 mAh g-1 at 0.2 C, coupled with a high-rate capability of 153.40 mAh g-1 at 10 C and long-term cycling stability, as evidenced by an 81.38% capacity retention after 450 cycles at 0.2 C (more than 220 days of continuous operation). Moreover, a 20 kg-scale pouch cell shows no significant capacity degradation over 300 cycles. This work demonstrates an effective approach for developing high-energy, high-power, long-cycle, resource-saving, and low-cost cathodes, offering insights into sustainable battery technologies that balance performance and cost.

ABSTRACT The rapid increase in electric vehicle (EV) adoption has significantly boosted the demand for lithium‐ion batteries (LIBs), creating an urgent need for sustainable recycling strategies. Discharging end‐of‐life LIBs is a critical preprocessing step before recycling. Electrical discharge via cables is the current industrial state of the art for large battery packs, whereas electrochemical discharge (discharging batteries in solutions) offers a reliable alternative for smaller and mixed waste streams. This study compares electrical and electrochemical discharge methods and examines their effects on the morphology and composition of electrode materials from spent LIBs. Additionally, it evaluates the potential of electrochemical discharge to enable a closed‐loop direct recycling process by recovering high‐quality active materials from spent LIBs. Characterization results reveal that the lithium content is higher on negative electrode sheets after electrical discharge than after electrochemical discharge. Unreacted lithium on Ni‐rich layered oxides can form residual lithium compounds, such as lithium carbonate (Li 2 CO 3 ) and lithium hydroxide (LiOH), which can trigger undesirable side reactions. PXRD analysis indicates that positive electrode materials subjected to electrochemical discharge retain their layered structure with minimal cation mixing, unlike those subjected to electrical discharge. Overall, the findings demonstrate that electrochemical discharge is more effective in preserving the chemical composition and structural integrity of active materials than conventional electrical discharge methods.

LiNi0.5Co0.2Mn0.3O2 (NCM523) is a promising cathode material for lithium-ion batteries with high capacity, stability, and environmental benefits, but conventional synthesis methods often cause structural degradation and cation mixing that hinder performance. In this study, a novel, optimized, and facile mixed-solvothermal approach mediated by ethylene glycol, water, and ethanolamine was employed to synthesize NCM523 cathode materials with enhanced crystallinity and optimized morphology. The effects of different calcination temperatures (700 °C, 800 °C, and 900 °C) on the structural, morphological, and chemical properties were systematically investigated. X-ray diffraction (XRD) analysis confirmed the formation of a well-ordered layered structure, with the sample mediated in ethylene glycol, water and ethanolamine and calcined at 800 °C (NCM-800) exhibiting superior phase purity and minimal cation disorder. The sample calcined at 800 °C exhibited the highest crystallite size of 37 nm and an intensity ratio of 1.42 in the case of the (003) to (104) planes, which indicates the lowest cation mixing of Li+/Ni2+ ions. X-ray photoelectron spectroscopy (XPS) further revealed optimal Ni2+/Ni3+ ratios (0.23) and lattice oxygen retention in NCM-800, indicating robust redox activity and minimal oxygen vacancies. Field emission scanning electron microscopy (FE-SEM) demonstrated that NCM-800 possessed uniform, densely packed spherical particles with minimal surface defects, contributing to improved mechanical integrity and electrochemical stability. Compared to samples calcined at lower or higher temperatures, NCM-800 achieved an optimal balance between crystallinity, particle morphology, and structural robustness. These findings highlight the potential of the mixed-solvothermal method as a promising, scalable, and cost-effective strategy for the synthesis of high-performance NCM523 cathode materials, paving the way for their application in next-generation lithium-ion batteries and advanced energy storage systems.

Lithium-rich manganese-based cathodes are promising for high-energy-density lithium-ion batteries but are hindered by poor cycling stability and rate capability. This study demonstrates that synergistic Zn2+ doping and Al2O3 coating effectively enhance their electrochemical performance. Structural analyses reveal that moderate Zn doping (LNCM@Zn2) expands the (003) interplanar spacing from 0.47 nm to 0.496 nm, lowers Li+ diffusion barriers, and suppresses transition-metal cation mixing. These modifications yield an initial discharge capacity of 276.4 mAh g-1 at 0.1C with improved rate performance. However, excessive doping (LNCM@Zn3) induces lattice overexpansion, causing structural instability and capacity fade. Concurrently, the Al2O3 coating acts as a protective layer, mitigating structural degradation and enhancing interfacial conductivity. The dual-modified Zn-doped and Al2O3-coated LNCM exhibits significantly enhanced cycling stability and superior high-rate capability compared to pristine materials. Optimal performance is achieved with the co-modified LNCM@Zn2@Al2O3, which maintains high discharge capacity at high current densities due to the combined benefits of the stabilized bulk structure (Zn doping) and protected surface (Al2O3). These results establish Zn doping coupled with Al2O3 coating as a viable strategy for developing high-performance LNCM for next-generation batteries.

ABSTRACT High‐nickel ternary materials are considered as promising cathode materials for lithium‐ion batteries, primarily due to their high specific capacity and energy density. However, the crystal structure of high‐nickel cathode materials undergoes significant changes during charge and discharge cycles. The accumulated stress leads to the formation and growth of microcracks along the inter‐particle boundaries, ultimately compromising particle integrity. Repeated volume contractions and expansions eventually cause further pulverization of the material. In this study, Al 3+ ion doping was employed to stabilize the layered structure of the high‐nickel ternary materials. Al 3+ ‐doped LiNi 0.8 Co 0.1 Mn 0.1 O 2 was synthesized by a one‐step solid‐state sintering method. The characterization confirmed that Al 3+ ions were successfully doped into the transition metal layers of the cathode material and formed stronger Al─O covalent bonds, which enhanced the stability of the bulk phase structure, suppressed phase transition, and microcracks. The cathode material doped with 1.5 mol.% Al 3+ exhibited excellent cycling stability, with a capacity retention rate increased by 15.01% after 600 cycles compared to the pristine specimen. In addition, Al 3+ doping reduces cation mixing and optimizes ion transport kinetics, the discharge capacity reached 145.5 mAh·g −1 at 10 C rate. Therefore, achieving Al 3+ ion doping through co‐lithium sintering provides an effective strategy for improving the performance of high‐nickel cathode materials in lithium‐ion batteries.

Quantitative image-analysis framework for precise discrimination of cation mixing in high-nickel NCM cathodes

This study reports on the green synthesis of high‐performance LiNi 1/3 Mn 1/3 Co 1/3 O 2 (NMC111) cathode materials using Actinidia deliciosa (kiwi) extract as a natural chelating and reducing agent. The electrochemical and structural performance of the green‐synthesized NMC (GS‐NMC) is systematically compared with NMCs prepared using sol–gel and solid‐state methods. Structural and surface analyses show that GS‐NMC possesses a highly ordered layered structure with minimal cation mixing, improved crystallinity, and increased surface area. Electron microscopy and Brunauer–Emmett–Teller analyses confirm a refined nanoscale morphology with well‐developed porosity. The X‐ray photoelectron spectroscopy results indicate reduced surface impurities and an optimal distribution of transition‐metal oxides. Electrochemical testing in a three‐electrode aqueous LiOH system demonstrates that GS‐NMC achieves enhanced surface redox activity, low interfacial resistance, and stable pseudocapacitive behavior (≈120 mAh g −1 within a ±1.0 V window) over 1000 cycles. In comparison, sol–gel and solid‐state samples exhibit higher polarization and faster capacity fading. Although tested under aqueous half‐cell conditions, the results show that green synthesis offers a promising route to produce structurally robust and electrochemically responsive NMC materials. The findings also highlight the promise of biogenic synthesis as a sustainable alternative to traditional methods and as a versatile platform for designing high‐performing cathode materials for next‐generation lithium‐ion batteries.

Ni‐rich layered oxides, such as LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811), offer high capacity but suffer from structural degradation and rapid fading under extended cycling. Herein, Mg doping as a structural stabilization strategy, directly comparing incorporation via precursor coprecipitation, solid‐state lithiation, and a novel two‐step route is introduced. All Mg doped NMC811 compositions show reduced cation mixing and enhanced cycling stability, with 0.1% Mg yielding the most favorable lattice evolution as revealed by operando X‐ray diffraction. For the first time, operando electrochemical dilatometry is utilized to investigate the doped NMC811, revealing direct correlations between electrode volume changes and electrochemical behaviour. While Mg primarily suppresses structural degradation, the solid‐state lithiation route delivers the greatest performance gains, outperforming both coprecipitation and the combined approach. This work demonstrates that targeted Mg incorporation can noticeably extend the lifetime of Ni‐rich cathodes and establishes operando dilatometry as a powerful tool for linking atomic‐scale stabilization strategies with macroscopic electrode mechanics.

Optimizing the electrochemical performance of nickel-rich cathode materials, specifically Ni0.8Mn0.1Co0.1(OH)2 (NMC811) precursors, involves careful adjustment of several factors, including modification, calcination temperature and lithium content. In this study, we explored the influence of lithium content on the structural, morphological and electro­chemical performances of LixNi0.8Co0.1Mn0.1O2, by varying 5, 10, 15 and 20 mol.% of Li excess. An appropriate amount of Li was found to suppress cation mixing effectively. Rietveld refinement showed that increasing Li content gradually reduced cation mixing by enhancing the occupancy of Li⁺ ions at the 3a sites, thereby hindering Ni²⁺ migration. Although a higher Li addition (20 mol.%) induced a slight lattice contraction, it exhibited the highest c/a ratio (the ratio of the lattice parameters c and a in the layered hexagonal structure), indicative of a well-ordered layered structure. Furthermore, Li exceeded 20 mol.% suppressed the H2/H3 phase transition, contributing to greater structural stability during cycling. While 15 mol.% Li excess achieved the highest initial discharge capacity (185.42 mAh g-1 at 0.1 C), 20 mol.% Li excess exhibited superior capacity retention (82.05 % over 80 cycles at 0.1 C). These results demonstrate the critical role of lithium stoichiometry in maintaining structural integrity and electrochemical stability of Ni-rich NMC cathodes, offering valuable insights for the design of high-performance lithium-ion batteries.

High nickel-rich layered oxide: The intrinsic role of cation substitution and metal-oxide coating in tuning cationic mixing and enhancing electronic conductivity

Growing demand for high-energy-density lithium-ion batteries (LIBs) has established high-nickel layered oxides as one of the most promising cathode candidates. Compared with commonly used high-nickel polycrystalline layered oxides, high-nickel single-crystalline layered oxides have attracted more attention due to their improved structural and cycling stability. However, the synthesis of high-nickel single-crystalline nickel cobalt manganese lithium oxide (NCM) particles requires a high calcination temperature, leading to particle agglomeration and aggravated Li+/Ni2+ cation mixing. In addition, high-nickel single-crystalline NCM could suffer from sluggish Li+ diffusion kinetics and structural degradation caused by severe phase transformation. Herein, we adopted the molten salt method to prepare a single-crystalline LiNi0.95Co0.025Mn0.025O2 cathode at a relatively low synthesis temperature to relieve particle agglomeration. Meanwhile, the Nb doping strategy is employed to broaden the interplanar spacing to facilitate Li+ diffusion, inhibit the Li+/Ni2+ cation mixing, and restrain the severe phase transformation. The obtained Nb-doped single-crystalline LiNi0.95Co0.025Mn0.025O2 (SC-NCM-N) cathode achieves a high reversible capacity of 216.4 mAh g-1 at 0.1 C (1 C = 180 mAh g-1), along with an improved capacity retention (88.7% after 100 cycles at 1 C) in comparison with the polycrystalline LiNi0.95Co0.025Mn0.025O2 (P-NCM, 66.8%) and pristine single-crystalline LiNi0.95Co0.025Mn0.025O2 (SC-NCM, 79.1%). This work offers insights into developing high-nickel single-crystalline cathodes for high-energy-density LIBs.

The development of high-energy lithium-ion batteries is essential for achieving a sustainable society. LiNiO2 has attracted significant attention as a potential alternative positive electrode material to conventional ternary layered oxides due to its high energy density and cobalt-free composition. However, the practical application of LiNiO2 is hindered by its poor electrode reversibility during cycling. On charging, nickel ions in LiNiO2 migrate from octahedral sites in the nickel layer to adjacent tetrahedral sites in the lithium layer in the high-voltage region and return to their original positions after discharge. This migration mechanism destabilizes remaining oxide ions in the vacant octahedral nickel sites, leading to surface reaction with electrolyte solutions and partial oxygen loss.1 To address this issue, adjusting the Li/Ni stoichiometry to introduce cation mixing through has been proposed.2 This approach effectively suppresses nickel ion migration to tetrahedral sites and enhances capacity retention. Furthermore, cation mixing has also been introduced by metal substitution.3 In this study, effects of niobium-substitution on electrochemical properties and structural evolution of pure nickel-based positive electrode materials are examined. Niobium-substituted LiNiO2 is synthesized by mixing nickel hydroxide, niobium oxide, and lithium hydroxide, and calcined at 650 °C for 12 hours under oxygen atmosphere. Niobium-substitution increases the amount of cation mixing and reduces primary particle size. Compared with non-substituted LiNiO2, the Nb-substituted samples demonstrate superior cyclability without sacrificing the reversible capacity. The impacts of niobium-substitution on the structural evolution during charging and electrochemical performance will be discussed in detail.

Lithium-ion batteries play a pivotal role in modern energy storage, powering devices ranging from portable electronics to electric vehicles and renewable energy systems. NMC 811 (Li0.8Mn0.1Co0.1O2) is a promising cathode material known for its high energy density. However, its performance is compromised by challenges such as cation mixing – specifically, the exchange of nickel and lithium ions within the crystal lattice – and surface degradation, which collectively lead to reduced cycle life and capacity fading. This research investigates multi-element coating and doping strategies aimed at enhancing the stability and longevity of NMC 811 cathodes. These multi-element approaches involve simultaneous doping and coating with multiple species to synergistically enhance material performance. Specifically, we focus on co-doping and co-coating NMC 811 with boron, aluminum, and niobium species synthesized using our collaborator’s one-pot process to mitigate degradation mechanisms. These approaches aim to stabilize the crystal structure, minimize detrimental phase transformations, and enhance interfacial stability during cycling. The materials were rigorously characterized to provide comprehensive insights into their structural, morphological, chemical, and electrochemical properties. Characterization techniques employed include X-ray Diffraction (XRD) for phase identification and crystallographic analysis, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) for detailed morphological and microstructural investigations, scanning transmission electron microscopy coupled with energy dispersive X-ray spectroscopy (STEM-EDS) for elemental distribution analyses, and X-ray photoelectron spectroscopy (XPS) for surface chemistry characterization. Furthermore, electrochemical performance was evaluated through extensive galvanostatic cycling and rate capability tests to systematically assess capacity retention, cycling stability, and performance at various charge/discharge rates. By addressing the underlying issues affecting NMC 811 cathode performance through these advanced multi-elemental doping and coating techniques, this study contributes substantially to the development of safer, more durable, and highly efficient lithium-ion batteries. The resulting improvements in battery durability, capacity retention, and overall performance are critical for meeting the demanding requirements of next-generation energy storage applications, particularly in electric vehicles and grid-scale energy storage solutions.

The integration of gel polymer electrolytes (GPEs) with high-Ni layered cathodes (NCM) has emerged as a promising strategy for realizing high-energy lithium-ion batteries, offering a potential solution to the failure modes commonly observed in liquid electrolyte systems. Yet the impact of residual monomers from incomplete curing on capacity fade has been largely overlooked.In this work, we present a comprehensive investigation of side reactions between unreacted ETPTA (ethoxylated trimethylolpropane triacrylate) monomers and NCM cathode surfaces within representative GPE systems, employing a combination of multiscale spectroscopic analyses and theoretical calculations. By systematically tuning monomer conversion during curing and linking it to interphase chemistry, transport, and electrode integrity, we reveal a direct conversion-structure-performance relationship.Density functional theory (DFT) and linear sweep voltammetry (LSV) indicate that ETPTA is oxidatively less stable than carbonate solvents. In thermally cured GPEs (TC-GPEs) with higher monomer content, initial charging triggers oxidative decomposition of residual monomers, producing organic ether/ester byproducts that drive interphase reconstruction toward an organic-rich, resistive CEI (cathode electrolyte interphase). In situ EIS reveals a sharp increase in interfacial resistance above the ETPTA oxidation threshold for low-conversion GPEs, whereas well-cured GPEs show more reversible impedance evolution.X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS) depth profiling confirm thicker organic CEI and suppressed LiF formation when residual monomers are abundant. This reconstructed interphase exhibits retarded ion transport and uneven growth across the cathode microstructure, which amplifies polarization and accelerates the onset of characteristic NCM failure modes. Structural degradation of NCM cathodes including transition metal reduction/dissolution, surface reconstruction toward rock-salt-like motifs, cation mixing, lattice distortion, and intergranular crack formation was elucidated by high-resolution transmission electron microscopy (HR-TEM) and X-ray diffraction (XRD). These chemical and structural changes manifest poorer rate capability, larger overpotentials, and inferior capacity retention compared with well-cured counterparts.Overall, this work identifies residual-monomer-initiated interphase reconstruction as a primary driver of capacity fade in NCM||GPE cells. The findings provide mechanistic insights into the multiscale fading processes in NCM‖GPE systems, highlighting the critical role of residual monomers in interphase instability, and guiding the design of more durable NCM‖GPE configurations for practical battery applications. Figure 1

High-Ni NCM cathodes (Ni ≥80%) have attracted extensive attention for high-energy-density lithium-ion batteries due to their high theoretical capacity. However, the high reactivity of Ni³⁺/⁴⁺ exacerbates critical issues, including electrolyte oxidation, irreversible phase transitions (layered → spinel → rock salt), gas evolution, transition metal dissolution, and microcrack formation. Moreover, the similar ionic radii of Ni²⁺ (0.69 Å) and Li⁺ (0.76 Å) promote cation mixing, compromising the stability of the layered structure. To prevent this, excess lithium sources (LiOH, Li2CO3) are introduced during synthesis, resulting in residual lithium compounds (RLCs) on the cathode surface, which can cause slurry gelation, increased interfacial resistance, and gas evolution. Although washing or wet coating processes are conventionally used to remove these RLCs, the use of solvents during such processes can damage the cathode and impose environmental and economic limitations. Dry coating strategy has been explored to overcome these limitations, but unlike wet coating, it often results in a non-uniform coating layer (island coating) due to nanoparticle agglomeration. In addition, low-Co/Co-free cathodes have also attracted attention due to the high cost of Co, but their reduced Co content leads to lower electronic conductivity and poor rate capability, posing another challenge for practical applications.In this work, Co3O4 nanoparticles were dry coated onto the surface of high-Ni/low-Co single-crystalline NCM960103 (= LiNi0.96Co0.01Mn0.03O2) cathodes, followed by post-annealing to induce reactions between RLCs and coating material. This process not only effectively removed RLCs but also reconstructed a concentration–structure dual-gradient architecture at the cathode surface. The resulting cathodes exhibited a thin and uniform Co-rich coating layer on the surface, and a disordered rock salt (DRX) layer was also constructed at the subsurface due to Ni–Co cation mixing during the high temperature post-annealing process. Such a Co-rich surface enhanced the electronic conductivity of the cathode material, which in turn significantly improved rate capability. Furthermore, due to the surface protection effect of the Co-rich coating layer and high chemical/structural stability of the subsurface DRX layer, cycling stability was also improved. This study demonstrates a facile dry coating strategy for enhancing the performance of high-Ni/low-Co cathodes, offering environmental, economic, and time-saving advantages over conventional washing and wet coating methods. Figure 1

Safety challenges in lithium-ion batteries (LIBs) have driven the development of all-solid-state batteries employing nonflammable electrolytes. [1] Among these, the sulfide-based Li₆PS₅Cl (LPSCl) stands out for its high ionic conductivity and ductility, enabling close electrode-electrolyte contact. At the same time, Ni-rich cathodes such as LiNi₀.₈Co₀.₁Mn₀.₁O₂ (NCM811) offer superior theoretical capacity but are prone to irreversible capacity loss and structural degradation when directly interfaced with sulfide electrolytes. [2, 3] Conventional oxide coatings can alleviate such issues, yet high-temperature sintering often triggers undesirable cation mixing and coating agglomeration, resulting in limited capacity retention and poor electrochemical stability. [4, 5]In this study, flash-light sintering (FLS) is introduced to fabricate a thin perovskite lithium lanthanum titanate (LLTO) layer on NCM811 powders with minimal thermal damage. By converting intense xenon-lamp irradiation into heat within milliseconds, FLS effectively prevents cation mixing in the Ni-rich core and inhibits nanoparticle agglomeration in the coating layer. Microscopic examination confirms the formation of a dense perovskite LLTO film, while chemical analyses indicate minimal side reactions between the cathode and sulfide electrolytes. Electrochemical impedance spectroscopy reveals a substantially lower charge-transfer resistance for the FLS-processed cathodes, facilitating enhanced lithium-ion transport. As a result, flash-light-sintered LLTO-coated NCM811 exhibits a high initial discharge capacity coupled with durable cycling performance.Additionally, further experiments were conducted to generate a controlled NiO-like layer on the surface of NCM811 using the same FLS process. By fine-tuning the xenon-lamp irradiation parameters, it was possible to observe and regulate the localized sintering depth, allowing only the outermost region of the NCM811 particles to form NiO-like phase. This strategic partial oxidation not only offers robust interfacial stability with sulfide electrolytes but also reduces the energy consumption and processing time compared to conventional thermal treatments, thereby lowering production costs. The NiO-like layer improves the overall electrochemical performance by mitigating side reactions and reinforcing mechanical integrity at the electrode–electrolyte interface, showcasing FLS as a versatile, cost-effective approach for engineering next-generation all-solid-state batteries.These findings highlight the potential of flash-light sintering as a rapid, scalable alternative to conventional heat treatments for temperature-sensitive cathode materials. By providing robust surface protection and maintaining high ionic conductivity, the FLS approach significantly improves the safety and cycle life of all-solid-state batteries, promoting further advancements in high-energy battery systems for electric vehicles.