▎ 摘　　要

NOVELTY - A composite comprises silicon dioxide in a graphene matrix. USE - Composite is used as electrochemically active material for forming electrode of lithium battery, field-emission device, biosensor, semiconductor device and thermoelectric device (all claimed). ADVANTAGE - The composite improves electrical conductivity of thermoelectric material. The batteries have improved capacity and cycle characteristics. DETAILED DESCRIPTION - A composite comprises silicon dioxide (SiO2) and/or silicon oxide of formula: (SiOx, where x is more than 0 to less than 2) comprised in a graphene matrix. INDEPENDENT CLAIMS are included for the following: (1) preparation of composite, which involves contacting a reaction gas comprising a carbon source gas and silicon dioxide, and thermally-treating the reaction gas-contacted silicon dioxide; and (2) electrochemically active material comprising the composite and an electrochemically active material.