Preparation method of iron phosphate and lithium iron phosphate

Abstract

The invention discloses a preparation method of iron phosphate and lithium iron phosphate. The preparation method of iron phosphate comprises the following steps: S1, preparing a mixed solution containing iron salt and phosphate; S2, performing spray pyrolysis on the mixed solution prepared in the step S1 to obtain iron phosphate, the concentrations of the ferric salt and the phosphate in the mixed solution in the step S1 do not exceed 1.5 mol / L, and the ratio of the amount of substance of the ferric salt to the amount of substance of the phosphate is (0.95-1.05):(0.95-1.05); the mixed solution in the step S2 is atomized at the rate of 10-100 ml / h and then reacts at the temperature of 500-750 DEG C, and the flow rate of carrier gas is 1-15 L / min. Compared with the prior art, the preparation method is simple, efficient, environment-friendly, controllable and stable, and the limitations of long time, large waste liquid amount and the like of an iron phosphate preparation method in the prior art are avoided.

Description

technical field [0001] The invention relates to the technical field of lithium batteries, in particular to the preparation technology of positive electrode materials of lithium ion batteries. Background technique [0002] With the emphasis on new energy vehicles in recent years, lithium-ion battery technology has developed rapidly. Lithium-ion battery is a kind of secondary battery, which mainly relies on the movement of lithium ions between the positive electrode and the negative electrode to work. During the charging and discharging process, Li + Intercalation and deintercalation between the two electrodes to achieve energy storage and supply. Lithium-ion batteries are mainly composed of positive electrodes, negative electrodes, and electrolytes. Among them, the performance of positive electrode materials has a direct impact on the performance of lithium-ion batteries, and its cost also plays a decisive role in the total cost of batteries. [0003] At present, the commer...

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Problems solved by technology

[0004] The synthetic method of ferric phosphate industrialization in the prior art is the liquid phase precipitation method, promptly uses hydrogen peroxide to oxidize divalent iron salt into ferric iron, and then uses phosphoric acid or phosphate and ferric iron to generate ferric phosphate precipitation, although this method can Ferric phosphate is prepared in batches, but it cannot effectively control the size and shape of the product. In addition, the entire process is relatively long and involves processes such as press filtration, washing, drying, calcination, and crushing, which are time-consuming Long (usually more than 12 hours) and will generate a lot of washing wastewater, increasing the difficulty of environmental protection

Chinese invention patent application document CN110002417A discloses a low-cost anhydrous iron phosphate preparation method, which specifically discloses adding iron oxide red material to phosphoric acid, adding anhydrous alcohol and stirring, passing through a spray dryer, using hot nitrogen as a heat source , maintain the nitrogen inlet air temperature at 220-250°C, and the discharge temperature at 110-130°C. After obtaining the dried material, wash it with absolute alcohol for several times until the free phosphoric acid content in the dried material is lower than 20ppm, and then wash the dried material The material is dried to obtain anhydrous iron phosphate. Although this method must avoid the long process flow and time-consuming problems of the liquid phase precipitation method, it still needs to be washed repeatedly to remove free phosphoric acid, resulting in a large amount of waste water and still operating. Complicated

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