Protecting lithium metal anode in all‐solid‐state batteries with a composite electrolyte

Abstract

Abstract The volume of the metallic lithium anode in all‐solid‐state Li metal batteries increases significantly due to the lithium dendrite formation during the battery cycling, and the rough surface of lithium metal also reduces Li‐ion transport in Li/electrolyte interface. In this work, we developed a solid polymer composite by adding the low‐cost Si 3 N 4 particles to protect the lithium anode in all‐solid‐state batteries. The Fourier transform infrared spectroscopy (FTIR) data show that the surface of 10 wt % Si 3 N 4 particles interacts with the polyethylene oxide (PEO) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt; the interaction restricts the anion mobility and improves the ionic conductivity (1 × 10 −4 S·cm −1 ) and lithium‐ion transference number (0.28) of the composite electrolyte. The lithium metal anode is well protected by the composite electrolyte in all‐solid‐state cells, including symmetric and Li/LiFePO 4 cells. The lithium dendrite growth suppression by this composite electrolyte indicates the possible application of these low‐cost composite electrolytes for lithium metal protection.