Research On Construction Of High-Energy Rechargeable Hybrid Zinc Battery And Electrode Interface Characteristics

Rechargeable zinc-air/metal oxide hybrid batteries should be expected to meet the rapidly growing needs of electronic products,electric vehicles and smart grids due to high energy density,high power density,good safety and low price.However,great challenges,such as dendrite growth,poor cycle life,and electrolyte leakage,still remain to realize industrialization.In this paper,a rechargeable zinc battery system is constructed by using KOH aqueous solution with adding Zn O as the electrolyte,Co₃O₄nanomaterials as the cathode electrocatalysts,and using copper mesh as the anode current collector.Reversible deposition/dissolution of zinc on the anode with three-dimensional?3D?structure is investigated.The charge-discharge performance of the battery rechargeable hybrid zinc battery with zinc mesh is studied.SiO₂and polyvinyl alcohol?PVA?are added to the electrolyte to form a gel electrolyte.The copper mesh is modified with rGO.The feasibility for constructing a flexible gel hybrid zinc battery system is studied.SEM and EIS analysis show that a 3D zinc anode forms on the anode current collector of copper mesh.Zinc is densely and uniformly deposited on the anode current collector of copper mesh when charged at a low current density.The deposited zinc particles become larger as the current density increases.When the cell discharges at a lower current density,the zinc anode is uniformly oxidized and dissolves,leading to the smooth electrode surface.The zinc anode surface becomes rough when discharged at a higher current density.Compared with the flat anode,the copper mesh anode reduces the internal resistance and charge transfer resistance of the battery,improves the storage capacity and utilization rate of zinc,and significantly improves the large-capacity charge and discharge performance of the battery.The cell charge at constant current of 25 m A for8 min,followed by standing for 1 min,and discharge to 0.9 V cutoff at constant current of 25 m A.The battery can stably run 4000 charge and discharge cycles?about1140 hours?,coulombic efficiency reaches about 98.2%with a flat higher discharge voltage plateau at around 1.71 V.This shows that the efficient operation with a long cycling life are realized.rGO is loaded onto the surface of copper mesh by a hydrothermal method.A gel electrolyte is prepared by adding SiO₂and PVA to KOH aqueous solution.The rGO/Cu-PVA-SiO₂gel battery system has almost the same electrochemical performance as the aqueous solution electrolyte.No significant reduction of average discharge voltage exhibits when the discharge rate increases from 1.05 C to 17.1 C.The gel electrolyte has a very limited impact on the catalytic activity for the cathode oxygen reduction reaction/oxygen precipitation reaction?ORR/OER?and the anode zinc deposition/dissolution.The results show that the battery can still stably perform4000 cycles.The Coulombic efficiency and voltage efficiency fluctuate in the range of 95.2?97.6%and 87.4?89.6%,respectively.The discharge voltage can still be maintained at 1.69 V.This provides a technical support for realizing a flexible rechargeable hybrid zinc battery.