LITHIUM MANGANESE OXIDE POSITIVE ELECTRODE ACTIVE MATERIAL, POSITIVE ELECTRODE PLATE CONTAINING SAME, SECONDARY BATTERY, BATTERY MODULE, BATTERY PACK AND ELECTRICAL DEVICE

The present application provides a lithium manganate positive electrode active material, comprising a lithium manganate matrix and a cladding layer as a "barrier layer" and a "functional layer". The cladding layer can not only "prevent" the transition metal ions which have been produced by the lithium manganate matrix from directly "running" into the electrolyte solution, but also "prevent" the hydrofluoric acid in the electrolyte solution from directly contacting with the lithium manganate substrate, and then prevent the lithium manganate matrix from dissolving out more transition metal manganese ions; as a "functional layer", the cladding layer contains various effective ingredients (oxyacid salts of aluminum, calcium and/or magnesium; organic bonding materials; oxalates and/or silicates) inside, which can reduce the transition metal manganese ions already present inside the battery through chemical reactions or adsorption effects, thus slowing down the generation of transition metal manganese and the decomposition of the SEI film (solid electrolyte interphase film) catalyzed by the transition metal manganese, thereby improving the cycling capacity retention rate of the battery.