Preparation method of carbon-coated lithium ferric manganese phosphate and lithium ion battery

The invention relates to the technical field of battery materials, in particular to a preparation method of carbon-coated lithium ferric manganese phosphate and a lithium ion battery. The preparation method of the carbon-coated lithium iron manganese phosphate comprises the following steps: soaking waste solid lithium iron phosphate separated from a lithium ion battery by using acid wastewater in a chlorination process titanium dioxide production process, and performing solid-liquid separation after soaking to obtain filtrate; performing ICP test on the filtrate; supplementing an iron source and/or a manganese source, a lithium source and a phosphorus source, and reacting to obtain a lithium ferric manganese phosphate precursor; and uniformly mixing the lithium iron manganese phosphate precursor, a carbon source, water and a dispersing agent to obtain lithium iron manganese phosphate slurry, and sequentially grinding, drying and roasting the lithium iron manganese phosphate slurry to obtain the carbon-coated