Solid-state batteries designed with high ion conductive composite polymer electrolyte and silicon anode

Polymer solid-state batteries (SSBs) possess the advantages of good interfacial contact, but their application faces low ionic conductivity. Here, three-dimensional (3D) porous composite polymer electrolytes with propylene carbonate plasticizer (3D-PPLLP-CPEs) fabricated effectively, displaying high ionic conductivity even at room temperature. Electrochemical in-situ polymerization of 3D-PPLLP-CPEs occurs during the first discharge process, avoiding safety issues caused by the liquid plasticizer without sacrificing the ionic conductivity of the electrolyte. Besides, the controllable in-situ generated LiF-enriched interface can avoid the Li dendrite growth. To further promote the practical value of SSBs, micro-sized [email protected]3PO4@C with high initial Coulombic efficiency was adopted to replace lithium foil. The LiNi1/3Co1/3Mn1/3O2 (NCM111)//Micro [email protected]3PO4@C full cell has achieved capacity of 129.1 mAh g−1 at a current density of 0.2 C, with capacity retention of 98.5% after 100 cycles, which is the best performance based on the Si anode in SSBs. Even at the high current density of 2.0 A g−1, the capacity remains 92.5 mAh g−1. This design of CPEs and electrodes has paved a new way to construct practical SSBs.