Graphite Oxide Based Metal Oxide Composite As Cathode Catalysts For Potassium Oxygen Battery And Electrochemical Performance Analysis

In recent years,environmental pollution and energy crises have intensified.In order to realize the large-scale utilization of renewable resources,the development of a low-cost and high-efficiency energy storage device has gradually become a current research hotspot.Because of its high specific energy（935 Wh/kg）,potassium oxygen battery is considered as a promising energy storage solution.However,potassium-oxygen batteries still face challenges such as high charging over-potential,ion transmission channel blocked by generated products,electrolyte decomposition and dendrite growth and accumulation.Aiming at the problem of the product blocking the ion transport channel,this article uses a catalyst material with good conductivity and stable structure to compound with a sparse porous graphite oxide material to increase the pores on the surface of the material,improve the transmission efficiency of ions and oxygen,and then improve the electrochemistry performance of the battery.Firstly,graphite oxide prepared by Hummers method and Mn O₂ prepared by hydrothermal method were compounded in different mass ratios,,and the composite material obtained was used as a potassium oxygen battery catalyst and assembled into a battery for electrochemical performance analysis.The results show that the graphite oxide/Mn O₂ dioxide composite material with a mass ratio of 8:1 has more obvious edge collapse,which is beneficial to the diffusion of oxygen in the catalyst.At a current density of 0.1 m A·cm^-2,the battery has a discharge capacity of 3032.04 m Ah·g^-1,a limited capacity of 300m Ah·g^-1,and three cycles.Secondly,the two ions of Zn²⁺and Mg²⁺are doped with Mn²⁺in different molar ratios by co-precipitation method to obtain zinc manganese metal oxide material（Zn Mn₂O₄）and magnesium manganese metal oxide material（Mg Mn₂O₄）as catalysts to assemble the battery and conduct electrochemical performance analysis.Find the material with the best performance ratio to compound with graphite oxide in order to improve the discharge capacity and cycle performance of the battery.The results show that Zn²⁺and Mg²⁺have different effects on manganese based materials.The addition of Zn²⁺can improve the stability of the structure and increase the capacity of the battery(3078.02 m Ah·g^-1).The addition of Mg²⁺can increase the defects on the surface of the material,then improve the cycle life of the battery（cycle 6 times）.Finally,due to the different effects of the two ions of Zn²⁺and Mg²⁺,in order to further improve the electrochemical performance of the potassium oxygen battery,the three ions of Zn²⁺,Mg²⁺and Mn²⁺were doped at a molar ratio of 1:1:2,and the co-precipitation method was used.Prepare ternary metal oxide material（Zn_xMg_yMn_zO₄）,compound it with graphite oxide according to different mass ratios,and then use it as a catalyst,assemble it into a battery and test its performance.The results show that the graphite oxide composite Zn_xMg_yMn_zO₄ material with a mass ratio of 7.5:1 has more surface pores,which is conducive to ion transport and improves the catalytic activity of the material.At a current density of 0.1 m A·cm^-2,the battery has a discharge capacity of 2844.13 m Ah·g^-1 and can be cycled 7 times.The synergistic effect of graphite oxide with Zn²⁺,Mg²⁺,and Mn²⁺ions effectively improve the discharge capacity and cycle performance of the battery.