Durable and Adjustable Interfacial Engineering of Polymeric Electrolytes for Both Stable Ni-Rich Cathodes and High-Energy Metal Anodes.

Achieving stable cycling of high-voltage solid-state lithium metal batteries is crucial for next-generation rechargeable batteries with high energy density and high safety. However, the complicated interface problems in both cathode/anode electrodes preclude their practical applications hitherto. Herein, to simultaneously solve such interfacial limitations and obtain sufficient Li + conductivity in the electrolyte, an ultrathin and adjustable interface is developed at the cathode side through a convenient surface in situ polymerization (SIP), achieving a durable high-voltage tolerance and Li-dendrite inhibition. The integrated interfacial engineering fabricates a homogeneous solid electrolyte with optimized interfacial interactions that contributes to tame the interfacial compatibility between LiNi x Co y Mn z O 2 and polymeric electrolyte accompanied by anticorrosion of aluminum current collector. Further, the SIP enables a uniform adjustment of solid electrolyte composition by dissolving additives such as Na + and K + salts, which presents prominent cyclability in symmetric Li cells (>300 cycles at 5 mA cm -2 ). The assembled LiNi 0.8 Co 0.1 Mn 0.1 O 2 (4.3 V)||Li batteries show excellent cycle life with high Coulombic efficiencies (>99%). This SIP strategy is also investigated and verified in sodium metal batteries. It opens a new frontier for solid electrolytes toward high-voltage and high-energy metal battery technologies.