In‐Built Quasi‐Solid‐State Poly‐Ether Electrolytes Enabling Stable Cycling of High‐Voltage and Wide‐Temperature Li Metal Batteries

Abstract

Abstract Developing solid‐state electrolytes with good compatibility for high‐voltage cathodes and reliable operation of batteries over a wide‐temperature‐range are two bottleneck requirements for practical applications of solid‐state metal batteries (SSMBs). Here, an in situ quasi solid‐state poly‐ether electrolyte (SPEE) with a nano‐hierarchical design is reported. A solid‐eutectic electrolyte is employed on the cathode surface to achieve highly‐stable performance in thermodynamic and electrochemical aspects. This performance is mainly due to an improved compatibility in the electrode/electrolyte interface by nano‐hierarchical SPEE and a reinforced interface stability, resulting in superb‐cyclic stability in Li || Li symmetric batteries ( > 4000 h at 1 mA cm −2 /1 mAh cm −2 ; > 2000 h at 1 mA cm −2 /4 mAh cm −2 ), which are the same for Na, K, and Zn batteries. The SPEE enables outstanding cycle‐stability for wide‐temperature operation (15–100 ° C) and 4 V‐above batteries (Li || LiCoO 2 and Li || LiNi 0.8 Co 0.1 Mn 0.1 O 2 ). The work paves the way for development of practical SSMBs that meet the demands for wide‐temperature applicability, high‐energy density, long lifespan, and mass production.