Performance Of Tin Based Alloys As The Negative Materials Of Lithium Ion Batteries Prepared By The Electro-deposition

Lihium-ion batteries are widely used as energy storage devices for various communication applications and digital products owing to their high power density and long cyclic life characteristics. Carbon materials are mainly used as the negative electrode in lithium ion batteries in business. Carbon has low theoretical capacity (374mAh/g) and practical capacity (200mAh/g) and cannot meet the demand of the next generation lithium ion batteries. There it is urgent to develop the new type negative electrode materials. Tin-based material is expected to replace the carbon material in lithium ion batteries because of high capacity of997mAh/g and high working potential. The problem is the huge volume-expanding in charge and discharge process which leads to severe degradation of the anode and dramatically shortens the cycle life of the batteries.In this work,tin alloy anodes were prepared by the pulse elcetro-deposition method, expecting to improve the battery properties by controlling the particle size of tin-based material.The microstructures of the tin alloy materials are investigated by X-Ray diffraction (XRD)and Scanning electroy microscope (SEM) and the electrochemical properties of lithium ion batteries using tin alloy as anode are studied by charge/discharge cycling,cyclic volatammery (CV) and AC impedance. The tin anode electrodeposited at current density of3.75mA/cm2shown the first-discharging capacity of442mAh/g and the largest-discharge capacity of331mAh/g in the later cycle. For the lithium ion batteries with tin anode sintered at200℃in air for48h, the largest discharge capacity is572.9mAh/g in the22th cycle. CuSn alloy anode prepared by sintering Cu coated Tin film in Ar at200℃for12h,the largest discapacity is910mAh/g. Heating the Cu coated Sn anode in the air for12h,the discapacity is decreased to350mAh/g. The results shown that O and Cu have been doped in the tin film in the heat treatment and the capacity and cycle properties of the batteries have been improved.