With reference to FIGS. 15A to 15C, for direct comparison with the PANa polyelectrolyte, Zn//NiCo batteries with different electrolytes including PVA and PANa are compared. It is observed that the existence of Zn2+ in electrolytes may improve the battery performance: strong redox peaks in the CV, much higher discharge plateaus and capacities at all C rates. It is important to note that Zn2+ is always absent in some polymer electrolytes such as PVA- and gelatin-based electrolyte.
It is also observed that, although a high concentration of 6 M KOH+0.2 M Zn(CH3COO)2 has demonstrated high battery performances, it may not compatible with PVA to form a free-standing film electrolyte. Therefore, only a diluted concentration may be used in PVA, thus the performance is naturally inferior.
With reference to FIGS. 16A to 16B, there is shown an electrochemical performances of solid-state Zn//NiCo batteries with PANa and PVA as electrolytes with identical contents of water (81.1%), Zn(CH3COO)2 (0.065 M) and KOH (1.95 M) operating with different currents of a, 5.8 C. b, 23 C. In spite of identical contents of water, Zn(CH3COO)2 and KOH in each electrolyte, the solid-state battery using PANa shows superior performances than that using PVA.
