2. Results and discussion
The Cu||Li half-cell test was electrochemically cycled to understand polarization, capacity retention, and CE. The cyclic CE indicates the rate of Li consumption during the Li plating/stripping process and the degree of electrolyte decomposition. The electrochemical performance of Cu||Li cell cycled at 0.5 mA·cm-2 with the plating stripping capacity of 2 mAh·cm-2 is shown in Figure 1a. Figure 1b and c illustrates the polarization voltages of the cells with E1 and E2 electrolytes, respectively. The cells with E2 electrolyte charged and discharged at 0.5 mA·cm-2 show a 22 mV and 29 mV polarization voltage for the 2nd and 10th cycles, respectively.