Study On Synthesis And Electrocheical Performance Of Phosphorus-Based Materials As Anode For Sodium Ion Batterries

Phosphorous cathode material has up to 2596 m Ahg^-1 sodium storage capacity,but it has the disadvantages of poor conductivity and poor cycling performance.The introduction of active/inactive metal elements to form metal phosphorous alloy can improve the conductivity of the material and effectively buffer the volume effect in the charging and discharging process,thus improving the electrochemical performance of the material.At present,most metal phosphates are synthesized by means of high-energy ball milling,high-temperature calcining and solid-state reaction,etc.These methods have complex operation steps,long cycle,high cost,and are not suitable for mass production.Therefore,their application is limited.In addition,in the process of electrode preparation,the synthesized powder materials also need to be mixed with conductive agent,binder.Not only the operation is complex and the cycle is long,but also reduce the overall specific capacity of the sodium ion battery.Electrodeposition method has the advantages of low cost,simple operation and short period,and it can directly achieve electrodeposition of multi-alloy in copper collector fluid.The prepared electrode can be used to prepare sodium ion battery as long as it is dried.In this paper,new electrode materials were prepared by electrodeposition and their electrochemical properties were systematically studied.The main research contents are as follows:1.Sb-Fe-P composite material was successfully prepared and Sb₄₇Fe₃₉P₁₄ anode material with the best performance was screened.Sb-Fe-P anode materials with different mole ratios,morphologies and structures were prepared by electrodeposition method by controlling current density.The experimental results show that the prepared Sb₄₇Fe₃₉P₁₄ electrode has the best electrochemical performance when the current density is 12.5 Adm^-2.Under the charge and discharge current density of 100 m Ag^-1,the charging capacity of Sb₄₇Fe₃₉P₁₄ electrode is 431.4 m Ahg^-1.After 200 cycles,its reversible capacity is still up to 422 m Ahg^-1,which is 97.8%of the first capacity.At the same time,the material has a good multiplier performance,which is mainly due to its microstructure, active/inactive metal synergy.Kinetic studies have shown that the excellent multiplier capability of Sb₄₇Fe₃₉P₁₄ electrode is due to the interaction between pseudo capacitance and solid state diffusion.2.Sb-Co-P composite material was successfully prepared,and the best performance of Sb₈₀Co₁₁P₉ anode material was screened.Sb-Co-P ternary alloy anode materials with different morphology,structure and composition were prepared by electrodeposition method by adjusting the composition of antimony potassium tartrate in the plating solution.The experimental results show that the prepared Sb₈₀Co₁₁P₉ electrode has excellent electrochemical performance when the concentration of antimony potassium tartrate in the plating solution is 33 g L^-1.In the charging and discharging process,the first charging capacity of Sb₈₀Co₁₁P₉ was 756 m Ahg^-1,the first coulomb efficiency was 84.4%,the reversible capacity was kept at 586.3 m Ahg^-1in the 100th cycle,and the capacity retention rate was 77.6%.This is mainly due to its microstructure and synergistic action of active/inactive metal matrix.In this paper,the preparation of Sb-Fe-P and Sb-Co-P alloy systems and their electrochemical properties were systematically studied.The best electrochemical properties of the alloy components were obtained through optimization,and the kinetic mechanism was studied by means of cyclic voltammetry and EIS impedance.The results of this study are helpful to explore the application of electrodeposition technology in the preparation of other metal alloy composites with excellent cycle life and high multiplier properties.