A critical SiOx layer on Si porous structures to construct highly-reversible anode materials for lithium-ion batteries.

A novel Si/SiOx porous structure with a SiOx coating layer of varying thicknesses was prepared via a simple annealing and acid washing process. When used as an anode material for lithium-ion batteries, the Si/SiOx porous structure with an ∼9 nm SiOx coating layer demonstrates significantly improved electrochemical performance with a high reversible discharge capacity of over 915 mA h g-1 after 500 long cycles at 1 A g-1. The lithiation mechanism of a SiOx layer of different thicknesses has also been investigated.