Multi-phase separated silicon based alloys as negative electrode material for lithium batteries

摘要

A particulate composite of silicon, tin, and aluminum (or other suitable metal) is prepared as a negative electrode composition with increased lithium insertion capacity and durability for use with a metal current collector in cells of a lithium-ion battery or a lithium-sulfur battery. This electrode material is formed such that the silicon is present as a distinct amorphous phase in separate matrix phases of crystalline tin and crystalline aluminum. While the distinct tin and aluminum phases provide electron conductivity, each phase accommodates the insertion and extraction of lithium in the operation of the cell and all phases interact in minimizing mechanical damage to the material as the cell experiences repeated charge and discharge cycles. Other suitable metals for use in the composite with silicon and tin include copper and titanium.

主权项

1. A lithium-ion or lithium-sulfur secondary electrochemical cell or battery comprising a negative electrode composition utilizing lithium; the lithium being inserted into a negative electrode composition during charging of the cell or battery and lithium being extracted from the negative electrode composition during discharge of the cell or battery; the negative electrode material comprising a composite consisting of silicon, tin, and a second metal element selected from the group consisting of aluminum, copper, and titanium, the composite being further characterized in that the silicon, tin, and second metal are present separately in separate phases, the tin phase and the second metal element phase being crystalline or amorphous and the silicon phase being amorphous, the composite of silicon, tin, and a second metal element being further characterized by nanoscale islands of amorphous silicon phase dispersed in a matrix of a tin phase and a phase of the second metal element.