Table 1.
Impedance parameters of ZnCo2O4–Li after different cycles in the fully charged state
| Fresh cell | 10th-charge cycle | 50th-charge cycle | 70th-charge cycle | 100th-charge cycle | |
|---|---|---|---|---|---|
| OCV (V vs. Li) open-circuit voltage | 2.2 | 2.85 | 2.90 | 2.80 | 2.90 |
| R e (Ω) electrolyte resistance | 3.9 | 4.4 | 4.0 | 4.2 | 4.1 |
| R (sf+ct) (Ω) surface film + charge transfer resistance | 149.4 | 72.8 | 47.1 | 47.9 | 48.2 |
| CPE(sf+dl) (µF) constant phase element due to surface film + double layer capacitance | 12 | 160 | 125 | 113 | 102 |
| W s (Ω) Warburg resistance | 690 | 2969 | 3826 | 3838 | 3894 |
| C i (µF) intercalation capacitance | 284 | 4.7 | 3.5 | 3.0 | 2.8 |