Research On Catalyst And Solid Electrolyte For Flexible Rechargeable Zinc Air Battery

This work has developed high-efficiency catalysts and electrolytes that can be used in flexible zinc-air secondary batteries.First,a phosphorus-nitrogen co-doped iron-nickel bimetallic organic framework porous carbon material was prepared and loaded with graphene（P-Fe Ni/NC@G）as a dual-functional catalyst for a flexible rechargeable zinc-air battery.The iron-nickel bimetallic framework material（Fe Ni-MOF）was prepared by hydrothermal method.Then,a phosphorus source was used to dope bimetal MOF under high temperature carbonization and coupled to load graphene,thereby obtaining P-Fe Ni/NC@G with bifunctional catalytic activity.In the oxygen evolution reaction（OER）,the overpotential of the P-Fe Ni/NC@G catalyst at a current density of 10 m A cm^-2 is 310 m V,which is much lower than the overpotential of 330 m V for the commercial catalyst ruthenium oxide.In the oxygen reduction reaction（ORR）,the half-wave potential of the P-Fe Ni/NC@G catalyst is 0.81 V,which is slightly lower than the 0.84 V half-wave potential of the commercial platinum-carbon catalyst.The open circuit voltage of the flexible rechargeable zinc-air battery integrated with P-Fe Ni/NC@G as the air cathode,polyvinyl alcohol-KOH as the solid electrolyte,and zinc sheet as the anode is 1.53 V,and the peak power density is 159 m W cm^-2,The charge-discharge voltage difference under the current density of 5 m A cm^-2 is 0.73 V,and the cycle stability of the flexible rechargeable zinc-air battery reaches 144 cycles.Its cycle performance is better than that of commercial platinum carbon-ruthenium oxide.Zinc-air battery with air cathode.This work not only expanded the database of air cathode materials,but also developed a new co-doping synthesis method for catalysts.Based on the research of the catalyst,we then developed a near-neutral gel polymer electrolyte（GPEs）composite（n-PVA-OH-MX）composed of polyvinyl alcohol（PVA）and hydroxyl-functionalized MXene.The flexible zinc-air battery performs ion exchange during the charging and discharging process.During this process,the performance of the solid electrolyte gradually decreases,which is mainly caused by the rapid loss of water during the charging and discharging process of the solid electrolyte.For this reason,it is necessary to design and develop solid electrolytes with high water-locking properties.However,high-performance solid electrolytes are manifested by high ionic conductivity and battery cycle time.Through our designed solid electrolyte n-PVA-OH-MX,not only has a higher ionic conductivity of 77.6 m S cm^-1,but also under the conditions of a current density of 2m A cm^-2 and a cycle time of 30 min,The charging and discharging cycle length of the flexible zinc-air battery is 162 h.We tested the discharge performance of the battery under different current densities,and found that the discharge voltage of the battery did not attenuate.The flexibility test of the battery was carried out under different bending angles,and the cycle performance of the battery remained unchanged.These high performances benefit from the interaction between the PVA’s three-dimensional porous network structure and the alkalized two-dimensional material MXene,so that the electrolyte has a high water retention effect.