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

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.