New anode systems for lithium ion cells

Samples of small particle size bismuth and electroplated Ni-Sn alloy were tested as anodes for lithium ion batteries to highlight the effects of volume changes during charge and discharge on the cycling life of the electrodes. Bismuth was used for its relatively high potential of Li-Bi alloys formation (0.8-0.6 V) which prevents other components within the electrode from being electrochemically active versus lithium in this potential window. Electrochemical tests have shown that the capacity fade during cycling is largely dependant of the amount of Bi in the electrode. Electroplated Ni-Sn alloys were directly used as anodes and do not need to be reground nor mixed with additives. Different electroplating conditions, leading to different morphology, highlight the leading role of the particle size of the active materials used in the lithium ion cells. (C) 2001 Elsevier Science B.V. All rights reserved.