The Synthesis Of Ternary Transition Metal Oxide For Supercapacitor Applications

As representative metals among transition metals,nickel,cobalt,manganese and other metals,their oxides have excellent electrochemical performance,their theoretical specific capacity is high,and the advantages of abundant sources and low cost have become research hotspots.However,In the actual charging and discharging process,there are problems such as low conductivity and poor reversibility,which limits its actual specific capacity and cycle life.This paper uses the synergistic effect of multi-metal ions and the advantages of combining graphene and nickel-cobalt-manganese metal oxides to prepare nickel-cobalt-manganese ternary transition metal oxides and composite materials of nickel-cobalt-manganese metal oxides and graphene,Through the collation and analysis of the experimental data,the influence of hydrothermal conditions on the properties of the material is studied,and the reaction mechanism is analyzed,which mainly includes the following research contents:(1)In this paper,petal-like ternary nickel-cobalt-manganese oxide(Ni_0.5Mn_0.5Co₂O₄)with a hierarchical structure was obtained by hydrothermal-calcination method.First,nickel salt,manganese salt,and cobalt salt were mixed with triethanolamine as an additive under hydrothermal conditions to obtain a precursor material,which is then calcined and decomposed at high temperature to obtain the final product.Combined with the electrochemical performance test results,the hydrothermal reaction at 140? for 12 h,and the calcination temperature at 500?,which are the synthesis conditions of the material with the best electrochemical performance.Three-electrode cell test results show that the specific capacity of the material is 1736.01 F g^-1at the current density of 1 A g^-1.After 2000 cycles,the capacity retention rate of the material was 85.00%,showing better cycle stability.The two-electrode cell test results show that the specific capacity of the supercapacitor is 54.56 F g^-1at the current density of 1 A g^-1.When the power density is 800 W kg^-1,the energy density can reach 19.40 Wh kg^-1.(2)We adopted a one-step hydrothermal method,combined with the advantages of graphene,to prepare a nickel-cobalt-manganese oxide/reduced graphene oxide(NCMO/r GO)composite material.Taking advantage of the strong oxidizability of potassium permanganate,nickel,cobalt,and manganese metals are evenly dispersed in the form of oxides on the surface of reduced graphene oxide.The test results of the three-electrode cell system showed that the specific capacity of the material is1304.10 F g^-1at the current density of 1 A g^-1.After 2000 cycles,the capacity retention rate of the material was 91.98%.The two-electrode cell system was tested with a composite material as the positive electrode and reduced graphene oxide as the negative electrode.The test results showed that the specific capacity of the asymmetric supercapacitor was 55.94 F g^-1at the current density of 1 A g^-1.When the power density was 800 W kg^-1,the energy density can reach 19.89 Wh kg^-1.The derivation of the synthesis method may provide guidance for the preparation of multi-element metal oxides of other elements.(3)Finally,a market economic analysis of the nickel-cobalt-manganese oxide/reduced graphene oxide composite material showed that its low production cost and excellent electrochemical performance.As supercapacitor electrode materials,nickel-cobalt-manganese oxide/reduced graphene oxide composite material have good market application prospects.