Figure 8. The reaction mechanism of Zn//ZMOP-4/PCNTs-6 ZISC is as follows: (a) GCD curve of Zn//ZMOP-4/PCNTs-6 ZISC under different charging/discharging states (current density is 0.2 A g-1); (b and c) XRD patterns of ZMOP-4 cathode and PCNT-6 anode at different charging/discharging states.
The seven major characteristic peaks of the typical α-MnO2 are distinctly described. And comparing the XRD patterns of the samples, the crystal framework of the ZMOP-4 electrode materials isn’t affected by charging-discharging process can be found. The XRD pattern almost shows non-change during the charging-discharging procedure, which indicates that the tunneling crystal structure of ZMOP-4 nanowires is reversible and stable during the ion insertion/extraction process. Meanwhile, it also can support the good cyclic stability of ZISCs. Similarly, as for PCNTs anode (Figure 8c ), there is no new crystal structure appearing, which also can indicate the excellent stability of ZISCs.