A Collaboration of Interfacial Engineering and Particle Assembly Enables Highly Stable Li‐Rich Layered Cathodes for Li‐ion Batteries

Lithium‐rich layered oxide cathodes (LLO) are renowned for their high specific capacity (>250 mAh g−¹) and have emerged as promising candidates for lithium‐ion batteries. However, significant capacity fades and voltage decay pose challenges to their commercialization, primarily due to the degradation of their original structure. In this study, a simple and rapid approach is presented that combines interfacial engineering and particle assembly to achieve a highly stable LLO cathode. This cathode features a single‐crystal LLO reassembled into a porous microsphere structure, along with a surface coating of polypropylene phosphate amide (PPA) formed through in situ cross‐linking of polyacrylic acid and ammonium polyphosphate, and a deuterogenic spinel interface layer. The dual protective coatings‐PPA and spinel‐effectively inhibit the dissolution of transition metals, delay structural deterioration, and enhance lithium‐ion diffusion. Additionally, the cross‐linked PPA layer strengthens the interconnection among LLO nanoparticles, improving the stability of the assembled microsphere structures while mitigating electrolyte corrosion. Consequently, the LLO@PPA electrode exhibits excellent capacity retention of 84.87% over 500 cycles at 0.5 C and shows significant improvements in rate performance. This work offers an effective modification strategy for developing next‐generation lithium‐rich cathodes with enhanced rate capacity and cycle life.