Lithium-metal batteries have attracted extensive attention due to the increasing demand for storage devices with high energy density. For the modification of lithium-metal battery, how to effectively inhibit the growth of lithium dendrites has become a key challenge. Ether electrolytes have been widely used owing to their good compatibility with lithium metal. However, they are still difficult to be applied in high-voltage battery systems because of the poor cathodic stability. In this work, we have dissolved the lithium carboxylate, LiCO2CF3, into a dimethyl ether-based ether solvent to achieve a relatively outstanding performance in both positive and negative electrodes. Using this dilute ether electrolyte (1 mol L-1), the Li∥Cu half-cells retain a Coulombic efficiency of 98.5% after 100 cycles at the current density of 1 mA cm-2 and lithium deposition amount of 1 mAh cm-2 for each cycle. Meanwhile, the Li∥NCM523 full-batteries also realize a capacity retention of nearly 80% after 100 cycles in the voltage range of 3.0-4.3 V. Moreover, when the concentration increases to 5 mol L-1, the Coulombic efficiency of the half-cells stabilizes at around 99.0% after 250 cycles under the condition of 1 mA cm-2 current density along with the average Coulombic efficiency of as high as 98.4% and the capacity retention rate of the full-batteries is nearly 95.4% after 100 cycles and over 83.8% after 200 cycles.
Keywords: Li-metal battery; LiCO2CF3; ether electrolyte; high concentration; high voltage.