Figure 6. (a) Cycling performance of Li/ZSONT/CC//LiFePO4(LFP), Li/Cu//LFP, and Li/CC//LFP cells at 2C. (b) Charging/discharging curves of Li/ZSONT/CC//LFP, Li/Cu//LFP and Li/CC//LFP cells in the 100th and 200th cycle. (c) Rate performance of Li/ZSONT/CC//LFP, Li/Cu//LFP and Li/CC//LFP batteries cycled from 0.2 to 5C. (d) Cycling performance of high-loading Li/ZSONT/CC//LFP, Li/Cu//LFP and Li/CC//LFP batteries at 2C (cathode loading=7.0mg cm-2, N: P=4.8).
To demonstrate the practical application of ZSONT/CC host, Li/ZSONT/CC//LiFePO4 (LFP) cells (with 4 mA h cm-2 Li) were assembled using ester-based electrolyte. For comparison, Li/Cu//LFP and Li/CC//LFP full cells were also assembled with the same parameters. As depicted in Figure 6a , Li/ZSONT/CC//LFP cell delivered excellent cycle stability with retaining capacity up to 77 mA h g-1 (with a capacity retention of 71%) after 4000 cycles at 2C, exhibiting a high average CE of 99.2%. In contrast, Li/Cu//LFP cell showed a fast capacity degradation and a low-capacity retention of 33.2% after 200 cycles, and Li/CC//LFP cell dropped to 71 mA h g-1 after 725 cycles (with a capacity retention of 66.5%). Figure 6b showed the charge/discharge curves of two full cells in the 100thcycle and 200th cycle. Although the voltage plateau gap of the three cells was similar in the 100th cycle, a much smaller polarization voltage was observed in Li/ZSONT/CC//LFP full cell after 200 cycles. Besides, Li/ZSONT/CC//LFP full cell exhibited a superior rate performance to the other two (Fig. 6c ), especially at large rates, the specific capacities of Li/ZSONT/CC//LFP full cell can reach up to 104.9 mA h g-1 at 5C, much better than Li/Cu//LFP ( 92.3 mA h g-1 at 5C ) and Li/CC//LFP ( 95.4 mA h g-1 at 5C). Moreover, an N/P ratio of 4.8 with 7mg cm-2 LFP was chosen for the full cell that was cycled (Fig. 6d ) at a charging/discharging rate of 2C. The cell can run for over 300 cycles with little capacity decay, demonstrating excellent cycling performance. As a comparison, Li/Cu//LFP full cell showed a lifespan of 70 cycles, and the capacity of Li/CC//LFP full cell faded to 45.8 mA h g-1 at the end of 300 cycles.