Preparation For Fe,Bi Compounds And Studies Of The Electrochemical Performance

With the rapid development of economy,the traditional fossil energy shortage and environmental pollution has become a serious social problem urgently to be solved,so the supercapacitor and alkaline rechargeable battery as representatives of clean renewable energy storage device has become a focus of research.In this paper,β-Fe OOH,BiFeO₃ and La-Bi₂O₃ were synthesised and studied as cathode electrode materials in C//β-Fe OOH asymmeteric supercapacitor,BiFeO₃//Ni（OH）2 and La-Bi₂O₃//Ni（OH）2 alkaline rechargeable battery respecitively.The main contents of this paper are as follows:1.The FeCl₃ as raw material,water and ethylene glycol as solvent,was prepared by solvothermal method of β-FeOOH material,then the prepared electrode plate and the carbon electrode assembly of C//β-FeOOH asymmetric supercapacitor,study its electrochemical properties.The optimum preparation conditions were obtained by orthogonal experiment.The concentration of FeCl₃ was 0.10 mol L-1,the volume ratio of ethylene glycol to water was 1:6,the hydrothermal temperature was 145 ℃,and the hydrothermal time was 6 h.Under the condition of the current density of 0.5 A g-1,the specific capacitance of the β-Fe OOH material was 642 F g-1,with a retention of72% after 800 cycles.2.Using Bi（NO₃）₃ and Fe（NO₃）₃ as raw materials,tartaric acid as complexing agent,Bi FeO₃ material was prepared by self propagating combustion,with the commercialization of nickel hydroxide cathode material composed of Bi FeO₃//Ni（OH）2 alkaline rechargeable battery,study on its electrochemical performance.Orthogonal experiment was used to prepare BiFeO₃ materials,and the optimum preparation conditions were as follows: Bi（NO₃）₃ concentration was 0.10 mol L-1,the reaction temperature was 500 ℃,the reaction time was 5 h,and the heating rate was 5 ℃ min-1.The specific capacitance of Bi FeO₃ was 199 mAh g-1at 1A g-1,with a retention of 62% after 500 cycles.The best preparation basis,prepared by ethanol as the solvent of Bi（NO₃）₃ and Fe（NO₃）₃ mixed solution,the preparation of Bi FeO₃ materials with more excellent performance.The specific capacitance of Bi Fe O₃ was 238 mAh g-1 at 1 A g-1,with a retention of 79% after 500 cycles.3.Using Bi（NO₃）₃ and La（NO₃）₃ as raw material and NaOH as precipitant,La doped Bi（OH）₃ was obtained by co-precipitation method.The optimum doping ratiowas nLa/nBi =0.075.Through further calcination of prepared La doped Bi₂O₃ based on optimal doping ratio,with the commercialization of nickel hydroxide electrode materials for La-Bi₂O₃//Ni（OH）2 alkaline rechargeable battery.The specific capacitance of La doped Bi₂O₃ was 240 mAh g-1 at 1 A g-1,with a retention of 86%after 500 cycles.