The Impact of the Addition of Rare Earth Elements to Si[sub 1−x]Sn[sub x] Negative Electrode Materials for Li-Ion Batteries

The impact of the addition of cerium and lanthanum-rich misch metal (MM, a mixture of rare earth elements) to silicon-tin alloys was studied using combinatorial and high-throughput materials science methods. Combinatorial libraries of , , and were prepared using the Dalhousie University combinatorial sputtering systems. The addition of MM increases the crystallization temperature of amorphous alloys, which makes their preparation in the amorphous state more likely by rapid solidification techniques like melt-spinning. Increasing the atomic fraction of MM in both and amorphous alloys decreases the reversible specific capacity of the alloys for lithium, but does not negatively impact capacity retention. Attractive compositions were identified in pseudoternary system that: (1) remain amorphous during charge-discharge cycling between 0.005 and vs ; (2) show excellent capacity retention; (3) have specific capacities as large as ; and (4) may be compatible with rapid solidification techniques for the production of amorphous materials. In particular, amorphous alloys containing tin and MM exhibited excellent capacity retention and reversible specific capacities near .