Substituted M[sub x]Cu[sub 6−x]Sn[sub 5] Compounds (M=Fe, Co, Ni, Zn) Designing Multicomponent Intermetallic Electrodes for Lithium Batteries

A strategy to exploit substituted M x Cu 6 − x Sn 5 ( M = Fe , Co, Ni, Zn) electrodes with NiAs -type structures that transform on electrochemical lithiation in lithium cells to intermediate face-centered-cubic Li 2 Cu 1 − y M y Sn structures before Li z Sn alloys ( 1 < z < 4.4 ) are produced is discussed. Zn substitution for Cu is possible only to x ≈ 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 Cu 6 Sn 5 . 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, ( i i ) electrode compositions, and ( i i i ) the reversibility of lithium insertion/metal displacement reactions in intermetallic electrode systems.