Single Bath, Pulsed Electrodeposition of Copper-Tin Alloy Negative Electrodes for Lithium-ion Batteries

Single-bath, pulsed electrodeposition of Cu-Sn alloy films was performed in a bath containing Lucent Technology's SnTech plating solution and copper sulfate. Films with varying Cu-Sn stoichiometries were deposited. Deposited films were between and 6 μm thick. These films were used as working electrodes in Li/Cu-Sn electrochemical cells to test their suitability as negative electrodes for Li-ion cells. As the Cu content in the film is increased, specific capacity is sacrificed for capacity retention. Films with a Cu-Sn atomic ratio of 0.27 (high Sn content) had a maximum specific capacity of 500 mAh/g, however capacity retention is only about 20% of the original capacity after 40 cycles. High Cu content films (Cu-Sn atomic ratio of 3.83) yield specific capacities near 200 mAh/g, with 80% capacity retention after 40 cycles. © 2003 The Electrochemical Society. All rights reserved.