High-performance garnet solid-state battery enabled by improved interfaces

Garnet solid electrolyte is expected to become the electrolyte of choice for next-generation solid-state batteries due to its high ionic conductivity and wide electrochemical window. However, the poor interfacial contact between electrolyte and electrodes limits the battery performance. In this work, the interface between the garnet and cathode is improved by utilizing a deep eutectic electrolyte (DEE) composed of 2,2′-dipyridyl disulfide and lithium bis(trifluoromethanesulphonyl)imide (LiTFSI) with high ionic conductivity and viscosity. It can favorably bind carbon and LiFePO4 particles, forming an intimate contact between the garnet and active material. In addition, by utilizing a succinonitrile gel electrolyte between the lithium metal anode and garnet, the assembled solid-state cell shows improved interfacial stability and promising cycling performance, i.e., a high initial discharge capacity of 134.2 mAh g−1 and capacity retention of 97.8% after 100 cycles at 0.2 C.