Research On The Reversible Conversion Of O₂ Catalyzed By Unsymmetric Feco Monatomic Configuration And Its Application In Flexible Zinc-air Batteries

Since the insufficient catalytic activity of the air cathode of zinc-air batteries during charging(OER)and discharge(ORR)greatly hinders their practical application.A good catalyst is required to reduce the reaction barrier of the air cathode during charging and discharging.Therefore,we designs an ultra-thin nitrogen-doped carbon nanosheet-supported Fe-Co bimetallic single-atom catalyst,which has strong conductivity,rich active sites and excellent catalytic activity in this thesis.This catalyst is used as a cathode catalyst for zinc-air batteries,which significantly improves the performance of zinc-air batteries In order to adapt to the real environment,we design quasi-solid electrolytes with high ionic conductivity,excellent water absorption and water retention properties,and good mechanical properties.It was assembled into a flexible zinc-air battery and showed good performance.The main progress made is as follows:(1)An ultra-thin nitrogen-doped carbon nanosheet-supported Fe-Co bimetallic single-atom catalyst(Fe-Co(DSA)@3DNC)was successfully prepared by salt template method.A special asymmetric Fe-Co diatomic pair structure is constructed in the nitrogen-doped carbon network,and the symmetry between the asymmetric Fe-Co bimetallic atomic pairs is broken,and the center of the active metal d band is reduced,which weakens the adsorption of oxygen intermediates and promotes the dissociation of oxygen intermediates,so Fe-Co(DSA)@3DNC has excellent ORR and OER activities.In the oxygen evolution reaction(OER),the catalyst has a potential of 1.65 V at a current density of 10 mA cm-2,and in the oxygen reduction reaction(ORR),the half-wave potential of the catalyst is 0.816 V.The zinc-air battery assembled as an air cathode catalyst has a stable open-circuit voltage and can provide a power density of 215 mW cm-2,with an specific energy of 1295 Wh kg-1Zn,and can stably cycle more than 4000 cycles at a current density of 5 mA cm-2.(2)A PANa-CMCS hydrogel with double crosslinking of sodium polyacrylate(PANa)and carboxymethyl chitosan(CMCS)was prepared.There is covalent crosslinking between PANa and CMCS,and a large number of amino groups and hydroxyl groups between CMCS molecules and PANa produce strong hydrogen bonding,and the various interactions between PANa and CMCS make PANa-CMCS have good performance.The flexible zinc-air battery assembled with its quasi-solid electrolyte has a maximum power density of 102.5 mW cm-2,and an specific energy of 997 Wh kg-1Zn,which can stably charge and discharge cycle for more than 3000 minutes.The flexible zinc-air battery can adapt well to the real environment,which can light up LED lights at various bending angles.It can still stably supply power to the LED screen after the battery breaks.It has good fire resistance which can ensure the safety of electricity.