Reducing resistances of all-solid-state polymer batteries via hot-press activation

All-solid-state lithium batteries (ASSLB) utilizing solid polymer electrolytes (SPEs) are attractive due to the enhanced safety and processability. However, operation of the cells usually requires elevated temperatures to overcome the low ionic conductivity or high interfacial resistance issue. Through this study, we identify that grain boundaries within SPE exist and play a crucial role on Li-ion transport and cell performance. Accordingly, a direct hot-press activation approach was proposed and demonstrated significant reduction of boundary resistance within the SPE, leading to a fourfold increase in room temperature (r.t.) ionic conductivity. The detailed morphological and structural study suggest a pressure-induced amorphization mechanism for the activation of room-temperature SPE. Through this facile activation procedure, all solid-state LiFeO₄ (LFP)|SPE|Li cells demonstrate improved performance for both high specific capacity and stable cycling at r.t.