g-C3N4: An Interface Enabler for Solid-State Lithium Metal Batteries.

Solid-state Li metal batteries (SSLMBs) have attracted considerable interests due to their promising energy density as well as high safety. However, the realization of a well-matched Li metal/solid-state electrolyte (SSE) interface remains challenging. Herein, we report g-C3N4 as a new interface enabler. We discover that introducing g-C3N4 into Li metal can not only convert the Li metal/garnet-type SSE interface from point contact to intimate contact but also greatly enhance the capability to suppress the dendritic Li formation because of the greatly enhanced viscosity, decreased surface tension of molten Li, and the in situ formation of Li3N at the interface. Thus, the resulting Li-C3N4|SSE|Li-C3N4 symmetric cell gives a significantly low interfacial resistance of 11 omega cm(2) and a high critical current density (CCD) of 1500 mu A cm(-2). In contrast, the same symmetric cell configuration with pristine Li metal electrodes has a much larger interfacial resistance (428 omega cm(2)) and a much lower CCD (50 mu A cm(-2)).