Tuning Solid Interfaces via Varying Electrolyte Distributions Enables High‐Performance Solid‐State Batteries

Solid/solid interface is the major challenge for high‐performance solid‐state batteries. Solid electrolytes (SEs) play a crucial role in the fabrication of effective interfaces in solid‐state batteries. Herein, the electrolyte distribution with varied particle sizes is tuned to construct solid‐state batteries with excellent performance at different operating temperatures. Solid‐state batteries with the configuration S/L (small‐sized SE in composite cathode and large‐sized SE in electrolyte layer) show the best performance at room temperature (168 mA h g −1 at 0.2 C, retention of 99%, 100 cycles) and −20 °C (89 mA h g −1 at 0.05 C), while the configuration S/S displays better performance at elevated temperature. The superior performance of S/L battery is associated with faster lithium‐ion dynamics due to the better solid/solid interface between active materials and electrolytes. Moreover, the inferior performance at 60 °C is caused by the formation of voids and cracks in the electrolyte layer during cycling. In contrast, the S/S battery delivers superior performance at elevated operating temperature because of the integrated structure. This work confirms that tailoring electrolyte size has significant effect on fabricating all‐climate solid‐state batteries.