The Preparation And Sodium-ion Energy Storage Characteristic Of Perovskite Fluorides Anode Materials

Lithium ion batteries（LIBs）have become the main power supply of portable electronic products due to high energy density.However,the continuous consumption of lithium resources,it is urgent to explore a rich element to replace lithium.Due to its abundant reserves,wide distribution and similar chemical properties to lithium,sodium based energy storage devices become the next generation of energy storage devices with great potential.Sodium based energy storage devices such as sodium ion capacitors（NICs）and sodium based dual-ion batteries（Na-DIBs）have attracted more and more attention due to their unique advantages.However,the radius of Na⁺is larger than Li⁺,the traditional electrode materials of lithium-based energy storage system are not suitable for sodium based energy storage systems.Therefore,we need to find electrode materials which are suitable for sodium ion intercalation/deintercalation to apply to sodium based energy storage systems.In this paper,we prepared two kinds of perovskite fluoride doped oxide reduction graphene composite materials controlled by pseudocapacitance.As negative electrode,they are used in different sodium based energy storage devices.The contents are as follows:1.The bimetallic perovskite fluoride doped oxide reduction graphene KCo_xMn_1-xF₃@r GO with different molar ratio of（Co:Mn=1-0,3-1,1-1,1-3,0-1）were prepared by one step solvothermal method.The composite materials Co:Mn=1-1 showed the best electrochemical performance comparing with other electrodes.The molecular formula is K_0.82Co_0.43Mn_0.57F_2.66by ICP test,which indicates K⁺and F^-vacancy.The KCMF（1-1）@r GO electrode shows the pseudocapacitance-dominated conversion-insertion hybrid mechanisms by ex-situ CV,XRD,and XPS.The designed Na-DIBs and NICs with the KCMF（1-1）@r GO anode and graphite（KS6）/activated carbon（AC）as cathodes demonstrate remarkable performance at room temperature.2.Polymetallic perovskite fluoride composite oxide reduction graphene hetero-nanostructure anode materials（KNi Co Mn F₃@r GO）with a ratio of nickel,cobalt and manganese of 1:1:1 was prepared by solvothermal method.The molecular formula is K_0.79Ni_0.25Co_0.36Mn_0.39F_2.83 by ICP test indicating K⁺and F^-vacancy.Through the ex-situ XPS,XRD,and CV test show conversion-insertion hybrids mechanisms with pseudocapacitance and diffusion control mixing hybrid kinetics.The sodium based dual-ion battery constructed by graphite（KS6）as the positive electrode and the KNCMF@r GO as negative electrode has showed excellent electrochemical performance at a wide temperature range.