Preparation method of battery composite material and precursor thereof

A preparation method of a battery composite material, comprising steps of:

• (a) providing phosphoric acid, a first metal source, a second metal source and water, wherein the formula of the phosphoric acid is written by H3PO4, the first metal source is a ferric source, the second metal source is a manganese source, and the formula of the ferric source is written by Fe7(PO4)6;
• (b) processing a reaction of the first metal source, the second metal source, the phosphoric acid and the water to produce a first product;
• (c) calcining the first product to produce a first precursor or a second precursor, wherein each of the first precursor and the second precursor is a solid-solution containing first metal and second metal, and the formula of the first precursor and the second precursor is written by (MnxFe1-x)2P2O7, and wherein x is greater than or equal to 0.5, and is less than or equal to 0.95;
• and
• (d) processing a reaction of the first precursor or the second precursor, and at least a first reactant to obtain a reaction mixture, and then calcining the reaction mixture to produce the battery composite material, wherein the formula of the battery composite material is written by LiMnxFe1-xPO4.