▎ 摘　　要

NOVELTY - Cathode active material comprises an alkali metal-magnesium-hydride (RMgH3), where R is one or a combination of at least two of potassium, sodium (both preferred), lithium, rubidium or cesium. USE - Cathode active material used for electrochemical device such as solid-state lithium-ion battery for use in an electronic device (all claimed). ADVANTAGE - The alkali metal elements are introduced into the cathode active material. The alkali metal has good flexibility, and can absorb deformation energy when the cathode active material is deformed, thus releasing the internal stress of the battery. The introduction of the alkali metal can also increase the cathode active material. The conductivity of the battery improves the specific capacity, Coulomb efficiency and cycle stability of the battery. The alkali metal-magnesium-hydride reduces the crystallinity of the mixed alloy and provides more grain boundaries, thus improving the electronic conductivity of the cathode active material. The preparation method of the cathode active material is simple, the raw material sources are wide, and the production efficiency is high. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for an electrochemical device. DESCRIPTION OF DRAWING(S) - The drawing shows an X-ray diffraction spectrum of the cathode active material. (Drawing includes non-English language text).