POSITIVE ELECTRODE ADDITIVE AND PREPARATION METHOD THEREFOR, POSITIVE ELECTRODE PLATE AND SECONDARY LITHIUM ION BATTERY

The present disclosure provides a positive electrode additive and a preparation method thereof, a positive electrode plate and a lithium-ion secondary battery. The positive electrode additive comprises a modified lithium carbonate. The modified lithium carbonate comprises a lithium carbonate particle and a polymer coating. The polymer coating coats a surface of the lithium carbonate particle and comprises a polymer. The positive electrode additive of the present disclosure has low cost and simple preparation method, when the positive electrode additive is applied in lithium-ion secondary battery, it can significantly improve lithium-ion secondary battery safety performance without affecting electrical performance of the lithium-ion secondary battery.