Si-SiOx-Cristobalite/Graphite Composite as Anode for Li-ion Batteries

A gentle route is developed to fabricate multicomponent nanosilicon-based composite by using SiO, NaOH and graphite as starting materials. The composite is composed of nanosilicon, nonstoichiometric SiOx, cristobalite and graphite (Labeled as Si-SiOx-cristobalite/graphite). Used as anode material in Li-ion batteries, the Si-SiOx-cristobalite/graphite exhibits high lithium storage capacity with good cycling stability and rate capability. At a current density of 100 mA g−1, the composite shows a stable reversible capacity of about 990 mAh g−1(Calculated on the total mass of the composite) and the capacity retention is nearly 100% after 150 cycles. Even at 1600 mA g−1, the stable discharge capacity of the composite is also over than the theoretic capacity of graphite. In the composite, cristobalite is inert to lithium, while the other components are involved in lithiation process during the first discharge. The excellent electrochemical performance of the Si-SiOx-cristobalite/graphite electrode is attributed to the uniform distribution of active components in inert media and the conductivity enhanced by graphite.