The pursuit of high energy density and safe lithium ion batteries (LIBs) is a urgent goal for the development of next-generation electric vehicles (EVs). All-solid-state batteries (ASSBs) with the combination of poly(ethylene oxide) (PEO)-based solid polymer electrolyte (SPE) and Ni-rich lithium nickel manganese cobalt oxide LiNi_0.8Mn_0.1Co_0.1O₂ (NMC811) cathode are promising candidates for EVs due to their improved energy density and safety. However, the low electrochemical oxidation window of PEO-based SPE and the instability of NMC811 at the charge/discharge process seriously restrict the battery performance. Herein, a high voltage stable solid-state electrolyte layer lithium niobium oxide (LNO) is coated on the NMC811 electrode surface by atomic layer deposition for stabilizing NMC811-PEO solid polymer batteries. Electrochemical tests show that LNO coating can stabilize the NMC811 active materials and mitigate the decomposition of SPE upon the cycling process, rendering a good performance of NMC811-PEO solid polymer battery. Mechanism studies by SEM, STEM, XAS, and XPS disclose that the uncoated NMC811 suffers from chemomechanical degradations along with oxygen release triggering the decomposition of SPE, which results in unstable cathodic electrolyte interphase. With LNO coating, chemomechanical degradations and oxygen release are inhibited and the decomposition of SPE is mitigated. This work renders a stable and high-performance high-energy-density SSB for high voltage application, which paves the way toward next-generation solid-state LIBs.

追求高能量密度和安全的锂离子电池（LIB）是下一代电动汽车（EV）发展的迫切目标。全固态电池（ASSB），结合了基于聚环氧乙烷（PEO）的固体聚合物电解质（SPE）和富镍的锂镍锰锰酸钴LiNi _0.8 Mn _0.1 Co _0.1 O ₂（NMC811）阴极由于其提高的能量密度和安全性而成为电动汽车的有希望的候选者。然而，基于PEO的SPE的电化学氧化窗口低以及NMC811在充电/放电过程中的不稳定性严重限制了电池性能。在此，通过原子层沉积在NMC811电极表面上涂覆高压稳定的固态电解质层氧化铌酸锂铌（LNO），以稳定NMC811-PEO固体聚合物电池。电化学测试表明，LNO涂层可以稳定NMC811活性材料并减轻SPE在循环过程中的分解，从而使NMC811-PEO固体聚合物电池具有良好的性能。通过SEM，STEM，XAS，XPS和XPS公开了未涂覆的NMC811遭受化学机械降解以及氧释放触发SPE的分解，这导致不稳定的阴极电解质界面。使用LNO涂层可以抑制化学机械降解和氧气释放，并减轻SPE的分解。这项工作为高压应用提供了稳定，高性能的高能量密度SSB，为下一代固态LIB铺平了道路。