Substituted MxCu6-xSn5 compounds (M = Fe, Co, Ni, Zn) designing multicomponent intermetallic electrodes for lithium batteries

A strategy to exploit substituted MxCu6- xSn(5) M = Fe, Co, Ni, Zn) electrodes with NiAs- type structures that transform on electrochemical lithiation in lithium cells to intermediate face- centered- cubic Li2Cu1-y MySn structures before LizSn alloys (1 < z < 4.4) are produced is discussed. Zn substitution for Cu is possible only to x approximate to 1 before the onset of secondary phases, whereas Co and Ni substitution appears to maintain the NiAs- type structure for the whole range of x (0 <= x <= 5). Substituted electrodes provide higher rechargeable capacities than Cu6Sn5. The results of the study have implications for tailoring and optimizing (i) the design of multicomponent intermetallic electrode structures containing elements that are either active or inactive towards lithium, (ii) electrode compositions, and (iii) the reversibility of lithium insertion/ metal displacement reactions in intermetallic electrode systems. (c) 2007 The Electrochemical Society.