Fig. 1 Schematic illustration of the electrochemical principle of the zinc ion battery[9]

Fig. 2 Ragone plots of zinc ion battery and other energy storage devices

Fig. 3 Charge and discharge curues of zinc ion batteries at current density of 0.1 A/g (a) and 8 A/g (b)[9]

Fig. 4 Specific capacity metal-air battery and stability in water of zinc and other metals[40]

Fig. 5 (a) Cycling performance of rechargeable zinc ion batteries with the unmodified ZnAB and ZnAB+AC (charge/discharge at 200 mA h/g); (b) CV curves of the unmodified ZnAB and ZnAB+12wt%AC at scanning rate of 0.1 mV/s[45]

Fig. 6 (a) Discharge curves of the zinc ion battery at various rates and (b) cycle life performance of the zinc ion battery at a continuous cycling 6C/6C charge/discharge test[9]

Fig. 7 Potential profiles of the zinc/α-MnO2 Zn-ion battery during the first (black line) and the second (red line) cycles, and their cycling performance up to 30 cycles (inset). (b) Ex-situ X-ray diffraction patterns of the electrodes at various charge and discharge stages: original electrode (1), half discharged electrode (2), fully discharged electrode (3), fully recharged electrode (4), and fully re-discharged electrode (5), as indicated in Figure (a)[68]

Fig. 8 Schematic illustration of the reaction pathway of Zn-insertion in the prepared γ-MnO2 cathode[63]

Fig. 9 (a) Cycle voltammograms of composite electrodes with different mass ratios of V2O5/C and (b) cycle performance of composite electrodes[44]

Fig. 10 (a) Capacity versus number of cycles of the full cell at the current density of 60 mA/g ; (b) Capacity versus number of cycles of the full cell at different current densities[73]

Fig. 11 (a) Effect of HD Zn compared to Zn sheet as an anode on charge and discharge profiles of cycle 2 at 5C rate and (b) fractional capacity vs. cycle number compared for sheet Zn and HD Zn at 5C rate[74]

Fig. 12 (a) CVs of ZnHCF in 0.5 mol/L Na2SO4 (1), 0.5 mol/ L K2SO4 (2), and 1 mol/L ZnSO4 (3) at scan rate of 2 mV/s ; (b) Cycle life tests at a rate of 1 C (square) and 5C (circle), 1C = 60 mA/g[75]