Sacrificial Additive C-Assisted Catholyte Buffer Layer for LiAlTi(PO)-Based All-Solid-State High-Voltage Batteries.

All-solid-state batteries with oxide electrolytes and high-nickel layered oxide cathodes (LiNiCoMnO and LiNiCoAlO, + + = 1, ≥ 60%) have received widespread attention owing to their high energy density and high safety. However, they generally suffer from interfacial structural instability when coupled with solid-state electrolytes, which strongly diminishes the longevity of the battery. In this work, we propose adding a sacrificial additive C to the catholyte buffer layer between LiAlTi(PO) (LATP) and LiNiCoMnO (NCM811) to enhance the electrochemical stability under high-voltage operating conditions. A uniform and robust cathode-electrolyte interphase (CEI) film enriched with LiPOF, LiPF, and CF is spontaneously formed on the surface of the cathode particles. In addition, the NCM811/Li solid-state battery delivers a discharge capacity of 150.3 mAh g with a retention of 85% after 200 charge-discharge cycles at 0.5 C. This study offers a practical approach toward realizing LATP-based all-solid-state high-voltage batteries characterized by exceptional cycling stability.