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

Abstract

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, Li_<i>x</i>BO_<i>y</i>, 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.