Study On Synthesis Of Copper Phosphate Material And Their Electrochemical Performance

At present,researches on cathode materials of secondary ion battery mainly focus on the embedded reaction mechanism materials.These materials have a good cycling performance,but a low reversible capacity.While the development of anode materials and electrolyte puts forward higher requirements for the capacity of cathode materials.Conversion reaction can provide a high specific capacity through a multiple electron transmission in redox reaction,which has become a new research direction.The conversion-reaction-based copper phosphate material has a high theoretical specific capacity(about 423 mAh g^-1)and stable thermostability which make it a very promising cathode material.However,the low electrical conductivity and poor reversibility during the conversion reaction process result in the bad electrochemical performance.In this paper,the effects of different process factors on the structure and morphology of copper phosphate materials were studied.Based on the results,the effects of the addition of carbon and manganese sources on electrochemical properties of copper phosphate materials were explored.The structural characterization was studied by XRD,SEM,TEM,Raman and XPS test.The cycle and rate performance were tested and the mechanism was further explored.The results demonstrate that the work in this paper has an obvious promoted effect to the copper phosphate materials.Results and discussion are described as follows:?1?The Cu₃?PO₄?₂ material can be synthesised at 600-800°C through a solid-phase method.The effects of temperature,heating rate and holding time on morphology and structure of the products were studied.It was found that the product has a better particle size and distribution obtained at a heating of rate of10°C min^-1 for 1 h.Cu₃?PO₄?₂ materials with different thickness of amorphous coating were prepared by controlling the heat treatment temperature.When the amorphous coating thickness is about 3 nm,the capacity remains at 134 mAh g^-1under the current density of 0.1 A g^-1 for 30 cycles.It shows the good sodium storage performance.?2?The Cu₃?PO₄?₂ material was respectively compounded with CNTs,super P and acetylene black by ball-milling method.Compared to the pure Cu₃?PO₄?₂material,the Cu₃?PO₄?₂/CNTs composite can effectively promote the conversion reaction and provide high sodium storage capacity.What's more,it is found that the Cu₃?PO₄?₂/super P composite exhibits the better lithium storage properties.Charging and discharging at the 0.05 A g^-1 for 30 cycles,the reversible capacity is about 115 mAh g^-1.?3?The three samples of Cu₃?PO₄?₂,Cu₄O?PO₄?₂/CuO/Mn₃PO₄ composite and Mn₂O₃ were obtained by controlling the molar ratio of copper and manganese in the raw materials to be 10:1,1:1 and 1:10.Among the three,the lithium storage capacity of Cu₄O?PO₄?₂/CuO/Mn₃PO₄ composite remains about185 and 101 mAh g^-1 at a current density of 0.05 and 0.5 A g^-1 after 50 cycles.When the current density increases to 2 A g^-1,the reversible capacity remains at87 mAh g^-1.Therefore,the Cu₄O?PO₄?₂/CuO/Mn₃PO₄ composite can maintain the high capacity and excellent cycling performance at the same time.