Preparation,Optimization And Zinc Storage Property Of Manganese Dioxide-Based Cathode Material For Aqueous Zinc-Ion Batteries

Although high energy density lithium-ion batteries（LIBs）now dominate the commercial rechargeable battery market,concerns about the long-term development of LIBs have arisen due to the rising costs caused by limited lithium resources,as well as environmental pollution and safety issues caused by organic electrolytes.Therefore,high-performance aqueous zinc-ion batteries（ZIB）have received a lot of attention.To address the problems of poor cycling stability caused by manganese dissolution and the irreversible distortion of lattice structure during charge and discharge ofα-Mn O₂-based cathode materials in aqueous zinc ion batteries,and low capacity due to poor intrinsic conductivity ofα-Mn O₂.In this thesis,the material properties were optimized by compound modification with carbon material graphene（GO）,compound modification with conducting polymer polypyrrole（PPy）,introduction of heterostructured titanium dioxide（Ti O₂）,and co-doping of metallic elements Ni and Co.（1）Firstly,α-MnO₂/rGO was prepared by compounding with carbon material graphene,and the compounding with carbon material is a efficient,simple and efficient modification method.The effect of different electrolytes on the electrochemical performance was investigated,and it was proved that the electrolyte with the addition of Mn²⁺can pre-equilibrate the dissolution of Mn and improve the cycling stability.The electrochemical performance and cycling stability improved by coating PPy on Mn O₂/r GO,which attributed to the synergistic effect of PPy and r GO.（2）TiO₂was introduced to form a heterostructureα-Mn O₂/Ti O₂by compounding with Mn O₂.The function of the heterostructure is to suppress the agglomeration and pulverization of Mn and ensure the stability of the structure,and on this basis,polypyrrole was utilized to form a coating,and the electrochemical properties of the obtainedα-Mn O₂/Ti O₂@PPy were further improved,and the stability of the structure could still be ensured after cycling.（3）The Ni-Co-MnO₂electrode can be cycled more stably at high current density 5 C and still has a high specific capacity(160.9 m Ah g^-1)after 400cycles.The high specific capacity(160.9 m Ah g^-1)meets the high performance requirements of aqueous Zn-ion batteries.