To probe the kinetic properties of the ZnO cloth based LIBs, we took the electrochemical impedance spectroscopy (EIS) measurements, and the results of non-cycled and 50th cycle are shown in Fig. 5(a). The equivalent circuit model of the studied system is also shown in Fig. 5(b) according to the works reported by others [
34-
36].
Rs represents the internal resistance of the test battery,
Rf and CPE1 are associated with the resistance and constant phase element of the SEI film,
Rct and CPE2 are correlated with the charge-transfer resistance and constant phase. As shown in Fig. 5(a), the first semicircle in the high-frequency region is correlated to Li-ion diffusion through the SEI layer, the second semicircle in the middle-frequency region represents charge-transfer resistances (
Rct), which corresponds to the charge transfer resistance and interfacial capacitance between the electrode and electrolyte, and the slopping line in the low-frequency region is related to solid state diffusion of Li-ion in the bulk electrode. The fitted impedance parameters are listed in Table 1. It can be seen that the SEI film resistance
Rf and charge-transfer resistance
Rct of the non-cycled are 6.71 and 36.41 Ω, which are significantly lower than those of 50th cycle (7.03 and 63.29 Ω). From the result, we can conclude that the inside of cells has been changed after cycled compared with the non-cycled, the same results have been reported before [
37-
39].