Multiphase Functional Regulation of the Interface between Sulfide Solid-State Electrolyte and Nickel-Rich Cathode

Integrating well-established nickel-rich cathodes with sulfide solid-state electrolytes is considered an effective approach for achieving high-energy-density sulfide-based solid-state batteries. However, the primary limitation lies in the interfacial degradation phenomena occurring between oxide cathodes and sulfide solid-state electrolytes. Guided by the distinct characteristics of organic polymers and inorganic materials, a hybrid coating layer incorporating both organic and inorganic components was engineered. In this design, polyvinylpyrrolidone, selected for its superior dispersibility and chemical inertness, functions as a buffer layer by preferentially filling surface depressions, enhancing structural and chemical stability. Meanwhile, LixBOy, characterized by its great ionic conductivity, mitigates the formation of space charge layers. Through synergistic interaction, the polycrystalline cathode demonstrated enhanced performance metrics, achieving a specific discharge capacity of 174.2 mAh g-1 at 1 C, while maintaining 76.8% capacity retention after 2000 cycles at 5 C. Most notably, when implemented with the single-crystal cathode, the system maintained 80% capacity retention for up to 4778 cycles at 5 C. This work demonstrates a multiphase coating paradigm for addressing interfacial challenges between sulfide solid-state electrolytes and nickel-rich layered oxide cathodes.