Solventless thermal crosslinked polymer protective layer for high stable lithium metal batteries

Abstract

Owing to its high theoretical capacity (3860 mA h g⁻¹), Li metal is emerging as a next-generation anode material. However, its volume expansion is a major obstacle in its commercialization because it causes the collapse of the solid electrolyte interphase layer and lowers the coulombic efficiency of the battery. Moreover, it induces dendrite formation, which causes internal short circuits. To overcome this obstacle, we propose the use of a cross-linked poly(ethylene glycol) dimethacrylate (c-PEGDMA) film containing ethylene oxide units as a protective layer for the metal surface. We prepared the c-PEGDMA by using a simple solventless process. It was coated on the surface of Li metal for a short time and thermally cured. The film was found to inhibit the volume expansion of Li metal during cycling, thereby reducing coulombic efficiency degradation and dendrite growth. The proposed surface stabilization technique is expected to be effective for Li metal batteries.