Reversible Low Temperature Li-Storage in Liquid Metal Based Anodes via a Co-Solvent Strategy†

Main observation and conclusion The application of lithium-ion batteries in cold climates has been hindered due to the decline in performance at low temperatures. The increased de-solvation energy and formation of Li dendrites at the anode surface emerge as the major challenges, which rely on the development of stable anode and compatible electrolytes. Herein, a self-healing GaInSn liquid metal (LM) based electrode coupled with a multi-solvent electrolyte is proposed toward reversible Li-storage at low temperatures. By using methyl butyrate (MB) as a co-solvent in 1 mol·L –1 LiTFSI of ethylene carbonate and diethyl carbonate, the electrolyte viscosity decreases from 52.07 to 13.75 mPa·s, while the ionic conductivity increases from 1.38 to 3.44 mS·cm –1 at –20 °C. Moreover, the Li/MXene@LM cells can display a discharge capacity of 500 mAh·g –1 , with capacity retention of 78% at –20 °C after 120 cycles. It is disclosed that a uniform LiF-rich solid electrolyte interface (SEI) layer on the anode is formed upon the addition of MB, which promotes the desolvation of Li ions at the interface of electrode/electrolyte especially at low temperatures. These results prove that MB as the co-solvent is well compatible with LM based anodes and holds great potential for the exploration of low-temperature energy devices.