Unlocking the potential of Lithium-rich layered oxides in all-solid-state batteries: Challenges and strategies

Lithium-rich cathode materials (LRCM) stand out as promising high-capacity cathodes (>300 mAh/g) for next-generation solid-state lithium-ion batteries (SSLIBs) owing to their unique anionic/cationic synergistic redox mechanisms. However, their deployment in liquid electrolytes is hampered by issues like irreversible capacity loss, voltage decay, and poor cycling stability. Integration with solid-state electrolytes (SSEs) offers a compelling pathway to overcome these limitations, capitalizing on the enhanced thermal stability, suppressed transition metal dissolution, and wider electrochemical stability window inherent to SSLIBs. This review systematically examines the evolution of LRCM within SSLIBs, emphasizing their structural advantages for high-voltage operation. Crucially, we identify and analyze three fundamental interfacial challenges impeding their performance: (1) sluggish interfacial charge transfer kinetics, (2) detrimental chemical/electrochemical side reactions at high voltages, and (3) mechanical degradation induced by oxygen release. To address these challenges, we provide a comprehensive and critical overview of state-of-the-art modification strategies, encompassing tailored material composition design, advanced interface engineering, and multiscale structural optimization. Furthermore, we propose forward-looking synergistic design paradigms that integrate machine learning-accelerated materials discovery with advanced characterization techniques, aiming to elucidate the critical structure-interface-property relationships governing LRCM performance in SSLIBs across multiple length scales. By bridging fundamental mechanistic understanding with practical engineering considerations, this review offers crucial insights and strategic guidance for the rational design and development of high-energy-density SSLIBs based on LRCM.