Green-low-cost rechargeable aqueous zinc-ion batteries using hollow porous spinel ZnMn2O4 as the cathode material

Rechargeable aqueous zinc-ion batteries (ZIBs) have been receiving much attention recently due to their potential large-scale applications for energy storage, although only a few cathode materials have been reported as the intercalation hosts for divalent Zn2+ ions. Here, we report competitive ZIBs based on hollow porous ZnMn2O4 as the cathode and zinc as the anode. ZnMn2O4 is firstly prepared through a solvothermal carbon template dispersed by polyvinyl pyrrolidone, followed by an annealing process. The galvanostatic charge-discharge measurement demonstrates that a reversible discharge capacity of 106.5 mA h g(-1) at 100 mA g(-1) after 300 cycles can be achieved with no capacity decay after the addition of 0.05 mol L-1 of MnSO4 into the electrolyte. Meanwhile, it exhibits a high capacity of 70.2 mA h g(-1) at a large current density of 3200 mA g(-1). The excellent cycle and rate performances are attributed to the synergistic effect of the deficient spinel structure of hollow porous ZnMn2O4 with residual carbon distribution and the inhibition of Mn dissolution during the charge/discharge process.