Fig. 5.

Electrochemical tests of LiCoO₂-Li full cells. (A) Capacity retention (Top), CE (Middle), and ASR (Bottom) of the Li||LiCoO₂ full cells containing 1 M LiPF₆ EC-DMC (EL-0), 1 M LiPF₆ FEC-DMC (EL-1), and 1 M LiPF₆ FEC-DMC + DTD (EL-4) electrolytes, respectively. Results from two cells in each case are shown. ASR was measured at the beginning of each discharge half-cycle. The batteries were first cycled at 0.1 C for three cycles and then charged at 0.2 C and discharged at 0.5 C repeatedly between 4.5 and 3.0 V. The LiCoO₂ electrodes are ∼23 mg cm⁻² in mass loading and ∼4.2 mAh cm⁻² in areal capacity. The Li electrodes are 50 µm in thickness and 10.3 mAh cm⁻² in areal capacity. EL-4 electrolyte enables the best capacity retention, highest average CE, and the lowest ASR during cycling. Inset in A, Middle (CE vs. cycle number) is the same plot with a larger y-axis scale. Inset in the A, Bottom (ASR vs. cycle number) is the same plot with a smaller y-axis scale. B–D are voltage profiles of the Li||LiCoO₂ full cells at different number of cycles using EL-4, EL-1, and EL-0 electrolytes.