Solid polymer electrolyte-based high areal capacity all-solid-state batteries enabled with ceramic interlayers

Solid polymer electrolytes (SPEs) based all-solid-state batteries (ASSBs) have attracted extensive attention as a promising candidate for next-generation energy storage systems. Typical ASSBs require high fabrication pressure to achieve high areal capacity, under which, however, SPEs struggle and risk damage or failure due to their low mechanical strength. There is also a lack of study on complex stress and strain SPEs experience during ASSB cell assembly processes. Here, ceramic solid electrolytes are selected as interlayers to address the stress–strain conditions during assembling. As a result, high areal capacity ASSBs with a LiCoO₂ loading of 12 mg·cm⁻² were assembled with SPE-based composite electrolytes. Around 200 cycles were carried out for these cells at a current density of 1 mA·cm⁻² under room temperature. The capacity decay of the battery at 200 cycles is observed to be as low as 0.06% per cycle. This work identifies a critical issue for application of SPEs in ASSBs and provides a potential strategy for the design of SPE-based ASSBs with high specific energy and long cycle life.