Stabilized, prelithiated silicon oxide particles for lithium ion battery anodes

Abstract

Although silicon-oxide based particles have stable capacity and high cycling efficiency as anode active material, they are known to suffer significant capacity loss during the first battery cycles. The addition of lithium silicate may help to mitigate the initial capacity loss, but it has been difficult to produce such anodes. During battery manufacture cell components are exposed to water, and lithium silicate is water soluble. As lithium silicate dissolves, the pH of the water increases, which can etch silicon, degrading the anode active material. Such degradation can be mitigated by doping lithium silicate with multivalent elements or by converting some silicon to metal silicide before water processing. Doping of lithium silicate makes it less soluble in water. And metal silicide is not as easily etched as silicon. While retaining the excellent capacity and stability of silicon-oxide based material, these methods and the structures they produce have been shown to increase the effective energy density of batteries that employ such structures by offsetting capacity loss in the first cycles.