Synthesis And Electrochemical Performance Of Multi-element Tin And Copper Based Alloy Negative Materials

Tin-copper (Sn-Cu) base alloy is considered as one of the anode materials of next generation lithium ions batteries. The Sn-Cu alloys prepared by using an electro-plating possess the advantages of low cost, controlled composition and thickness, high specific capacity and good cycling. This paper aim to prepare the multi-element Sn-Cu base alloy negative materials from below three kinds of solution systems by using the electro-plating possess with a pulse current. The charge-discharge cycle, XRD, electrochemical impedance and environmental SEM were employed to study the electrochemical performance and the effect of the preparation condition on the electrochemical performance of the samples.First, several kind of Sn-Cu alloys with a Cu₆Sn₅ structure were prepared from a solution dissolved with NaH₂PO₂·H₂O, Na₂SnO₃·3H₂O, NaOH and CH₃COONa . While the solution was dissolved 15g/L of NaH₂PO₂·H₂O, the as-prepared sample exhibits a capacity of 666mAh/g in the 1st cycle and 349mAh/g in the 40th cycle at a current of 100mA/g in the voltage range of 0.01 to 1.7V .Second , several kinds of Sn-Cu-Ni alloys with a monoclinic Ni₃Sn₄ structure (Space group : C2/m) were prepared from a solution dissolved with C₁₀H₁₄N₂ O₈Na₂·2H₂O, KNaC₄H₄O₆·4H₂O, K₄P₂O₇ , Na₂SnO₃·3H₂O and NiSO₄·6H₂O. While the solution dissolved with 45g/L of NiSO₄, the as-prepared sample exhibits the best electrochemical performance in all samples, which discharge capacities are 764 mAh/g in the 1st cycle and 405 mAh/g in the 50th cycle at a current of 100mA/g in the voltage range from 0.01 V to 1.5 V. The charge-discharge efficiency is high during cycling.Third, several kinds of Sn-Cu-Zn alloys were prepared by using a two steps electro-plating process , in which the tin film was firstly deposited on a Cu film by using a electro-plating method to prepare several Sn -Cu film samples from a solution dissolved with Na₂SnO₃·3H₂O, NaOH and CH₃COONa .And then different Sn-Cu-Zn alloysprepared by electro-plating Zn with different time on the as-prepared Sn-Cu film from a solution dissolved MnSO₄·H₂O, ZnSO₄·7H₂O, Na₃C₆H₅O₇·2H₂O and Na₂S₂O₃. Experimental results show that the as-prepared Sn-Cu-Zn prepared by sample electro-deposed Zn for 2 min exhibits the best electrochemical performance in all samples, which exhibits a capacity of 543mAh/g in the 1st cycle, and its capacity fading ratio is 25.7% of the initial capacities in the 30 cycles at a current of 100mA/g in the voltage range of 0.01V to 1.7V with a current efficiency of 90%.