Novel propylene carbonate based localized high concentration electrolyte with high voltage, flame retardant and wide temperature characteristics enables excellent electrochemical performances of lithium metal batteries

Abstract

The high reactivity of Li metal anodes and dendrite issues in lithium metal batteries (LMBs) pose serious challenges to the electrolytes. Herein, a novel propylene carbonate (PC) based localized high concentration electrolyte (LHCE) for LMBs is rationally designed, which achieves flame retardancy, a broad electrochemical stability window, dendrite-free Li deposition, and a wide operating temperature range. It enables Li‖NMC811 with a 50 μm thick Li metal anode and high loading capacity NMC811 cathode (14.8 mg cm⁻², 2.96 mA h cm⁻²) to achieve 80% capacity retention after 100 cycles at a high cut-off voltage of 4.5 V. Li‖NMC811 achieves 85% capacity retention after 100 cycles at 55 °C, and it exhibits a discharge specific capacity of 140 mA h g⁻¹, 95 mA h g⁻¹ and 47 mA h g⁻¹ at different low temperatures of 0 °C, −20 °C and −40 °C, respectively. Moreover, LHCE is helpful for the formation of a solid electrolyte interphase (SEI) that is rich in inorganic species, which is able to improve ion transport efficiency and suppress parasitic reactions at the electrode–electrolyte interface.