Bifunctional lithium-montmorillonite enabling solid electrolyte with superhigh ionic conductivity for high-performanced lithium metal batteries

Solid-state lithium-metal batteries (SSLMBs) have been regarded as one of the most promising battery systems due to their high energy density and excellent safety. However, the low ionic conductivity of solid electrolyte (normally < 1 mS cm−1) does not meet the practical application of SSLMBs. Herein, we propose a vertically-aligned composite solid electrolytes (VA-CSE) with dual Li+ transportation paths: one dimensional (1D) Li+-transportation highway in lithium montmorillonite (Li-MMT) layer along aligned poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) channels and unique Li+ hopping path created by aggregated ions pairs in polymerized vinyl ethylene carbonate-based electrolyte. This Li-MMT/PVDF-HFP solid electrolyte (Li-MPSE) exhibits superionic conductivity of 1.99 mS cm−1 and high lithium transference number (0.73) at 30 °C. With this superior Li-MPSE electrolyte, Li/LiFePO4 solid-state batteries stably cycle 200 times with 99.7% capacity retention at 0.5 C and pouch cell also presents excellent electrochemical performance and safety.