▎ 摘　　要

NOVELTY - Silicon oxide-based composite cathode active material comprises magnesium silicate (I); crystalline silicon; and an alkali metal element. USE - The silicon oxide-based composite cathode active material is useful for lithium secondary battery (claimed) of small electronic devices e.g. smartphones to large systems e.g. new and renewable energy storage systems, energy storage source for future technologies e.g. drones and robots, wearable devices, flexible devices and electric vehicle. ADVANTAGE - The silicon oxide-based composite cathode active material has excellent thermal stability; suppresses the leakage of magnesium gas, thus the initial efficiency can be significantly improved by increasing the homogeneity of the reaction; and has improved electrochemical performance by reducing the content of magnesium oxide, which is not reactive with lithium and can reduce electrochemical performance as an insulator. DETAILED DESCRIPTION - Silicon oxide-based composite cathode active material comprises magnesium silicate of formula (MgxSiOy) (I); crystalline silicon; and an alkali metal element. x=0.05-2; and y=2.5-4. An INDEPENDENT CLAIM is also included for manufacturing silicon oxide-based composite cathode active material, comprising (a) preparing a mixed powder by adding the above raw materials to be applied on the first mixed material; (b) performing primary heat-treating of the mixed powder at 400-1000° C; and (c) washing the mixed powder, filtering and drying to obtain silicon oxide-based composite.