Ion conducive solid-electrolyte-interphase on lithium metal prepared by NO3− short-range compensation strategy for better cycle life of high-voltage batteries

Abstract

Carbonate-based electrolyte has the advantage of anti-oxidation ability at high-voltage, and the resultant lithium (Li) metal batteries coupling with ternary metal oxide cathode show high energy density. However, the drastic side reaction between carbonate and Li metal electrode induces low ionic conductivity of in-situ solid-electrolyte-interphase (SEI) and a low cycling stability of Li metal battery. Here, we propose a strategy of NO3− consumption and short-range compensation on Li metal surface to improve its cycling stability. By constructing a uniform PVDF/LiNO3 (PFN) prefabricated layer on Li metal surface in ether/carbonate electrolyte, both the dissolution and decomposition kinetics of solid LiNO3 are enhanced due to the added ether solvent and shortened compensation distance. As a result, the consumption of LiNO3 is rapidly compensated near to Li metal, effectively enhances the content of conductive Li3N and LiNxOy in the SEI. The cycle life (2000 h) of a Li//Li battery consisting of PFN layer and the carbonate/ether electrolyte is about 2 times longer than that of carbonate/ether electrolyte with saturated LiNO3. Capacity retention rate of the assembled Li//NCM811 full battery with a high loading of 23.6 mg cm−2 is as high as 84.0 % after 115 cycles.