Coordination-induced high-dielectric polymer coatings for high-energy-density lithium batteries

Abstract

The full utilization of lithium ions through high-voltage operation is redeemed as one of the most promising ways to boost the energy density of the current lithium-ion batteries (LIBs). Nevertheless, the reliable operation of high-voltage LIBs is mainly inhabited by the detrimentally interfacial reactions on the cathode surface upon high charge voltages, which is closely correlated to the solvation structure of the electrolyte. In this work, we report a fluorine-carbon-oxygen (F-C-O) coordination-induced dielectric-enhancement strategy to manipulate the electrolyte solvation structure and thus improve the lithium utilization of cathode. To realize this, graphene oxide (GO) with abundant oxygenated groups is introduced to trigger the spontaneous formation of β-phase polyvinylidene fluoride (β-PVDF) with high dielectric constant coated on a polypropylene (PP) separator. The high-dielectric PVDF@GO/PP separator is endowed with the ability to manipulate the distribution and migration of ions, thus significantly improving the lithium-ion utilization rate of the cathode, maintaining the cathode robustness in the high-voltage cycling, leading to an appreciable improvement in the discharge capacity, rate performance, and cycling stability of LiNi0.8Co0.1Mn0.1O2 (NCM811)/Li cell at wide-temperature.