A composite solid electrolyte with a framework of vertically aligned perovskite for all-solid-state Li-metal batteries

Composite solid electrolytes (CSEs), which inherit the flexibility of polymer electrolytes and the high ionic conductivity of ceramic electrolytes, hold a great potential to realize all-solid-state Li-metal batteries (ASSLMBs) with high energy density and enhanced safety. However, conventional preparation methods for CSEs by randomly dispersing ceramic particles in a polymer matrix fail to provide effective Li+ conducting networks, thus severely sacrificing the high ionic conductivity of ceramic fillers. In this work, we develop a framework of vertically aligned perovskite Li0.33La0.557TiO3 (LLTO) embedded in a PEO-LiTFSI matrix to maximize the ionic conduction. The vertically aligned LLTO structure prepared by an ice-templating method provides fast, continuous and the shortest pathways for Li+ transport, thus boosting the ionic conductivity from 0.038 to 0.13 mS cm−1. As a result, a Li|LiFePO4 full battery assembled with the developed CSE is capable of delivering a specific discharge capacity of 144.6 mAh g−1 at 1 C at 60 °C with a high capacity retention of 96.0% after 100 cycles.