Combinatorial Study of Tin-Transition Metal Alloys as Negative Electrodes for Lithium-Ion Batteries

Abstract

A survey of the structural and electrochemical properties of combinatorially sputter deposited -transition metal alloys [ ; , , , , , , , ] is reported. Over 512 compositions have been studied. Sputtered libraries of with , , , and show no evidence of nanocrystalline or amorphous phases at any composition. By contrast, libraries of with , , , and show composition ranges where the films are highly nanostructured or amorphous, suggesting that these elemental combinations are better glass formers. The transition metal contents of the amorphous or nanostructured phase regions are and to at least for , to at least for , for , and for . Electrochemical tests using a 64 channel combinatorial electrochemical cell show that the specific capacity of the alloys drops with transition metal content, as expected. The system shows an amorphous phase with the largest specific capacity, primarily because the amorphous phase is reached at the lowest transition metal content for . Capacity retention vs cycle number is generally best for those compositions that are amorphous or highly nanostructured. Arguments are presented to suggest that amorphous alloys are the best choice among alloys. Comparison with literature results for samples prepared by mechanical alloying, electrodeposition, vacuum deposition, etc. is made.