Morphology Control And Performance Optimization Of CuCo₂O₄ As Cathode Catalyst For Nonaqueous Lithium-Air Batteries

The nonaqueous lithium-air batteries have high theoretical capacity,which is a very promising next-generation power system.However,the nonaqueous lithium-air batteries are still facing some serious challenges,such as poor stability,low energy conversion efficiency,poor cycling performance and anode corrosion.Researching and exploring highly effective cathode catalysts is one of the best ways to improve the performance of lithium-air batteries.Using highly active electrocatalysts and optimizing the morphology of air electrodes can promote the ORR/OER and reduce the overpotential,significantly improve the performance of lithium-air batteries.Spinel oxide is one of the best catalysts used in lithium-air battery because of its advantages of low-cost and high natural abundance,which has been proved that own the bifunctional catalytic activity.In this paper,flower-like CuCo₂O₄,CuCo₂O₄ nanosheets and CuCo₂O₄ nanoneedles spinel oxides are synthesized via a facile hydrothermal method followed by low temperature calcination.The characterization and electrochemical performance of the different morphologies of CuCo₂O₄ spinel oxides are tested.The Li₂O₂ formation mechanism and relationship between the catalytic performance and morphology of CuCo₂O₄ are discussed.The main conclusions are as follows:?1?Flower-like CuCo₂O₄ cathode catalysts are synthesized via a facile hydrothermal method followed by low temperature calcination.The sample calcined at the temperature of 400?possess best crystalline structure.And the concentration of NH₄F influence on CuCo₂O₄ morphology is explored.With the addition of 2 mmol NH₄F,CuCo₂O₄ have higher specific surface area and better electrochemical performance,possess specific surface area of 64.2 m² g^-1 and discharge capacity of 9869 mAh g^-1 and cycle 64 times with the capacity of 500 mAh g^-1.?2?CuCo₂O₄ nanosheets and CuCo₂O₄ nanoneedles have been in-situ grown on carbon textiles via a facile hydrothermal method followed by low temperature calcination.The as-prepared composite can be directly utilized as self-supported flexible cathodes in nonaqueous lithium-air batteries.The CuCo₂O₄ can significantly reduce the charge and discharge overpotential,enhance reversible charge capacity and possess outstanding cycling performance.Compared with the CCO NNs/CTs cathodes,the CCO NSs/CTs cathodes have greater discharge capacity and better cycling performance.The CCO NSs/CTs possess discharge capacity of 11793 mAh g^-1 and cycle over 65 times with the capacity of 500 mAh g^-1.?3?Furthermore,flexible lithium-air batteries have been assembled,showing excellent cycling stability for over 46 cycles with the capacity of 500 mAh g^-1 and have no significant decline after 200th bending,which fully prove that the flexible CCO NSs/CTs cathodes have broad application prospects for flexible devices.