Preparation method of nano spherical ferric phosphate as well as nano ferric phosphate prepared by the method, lithium ferric phosphate and lithium battery

Abstract

The invention discloses a preparation method of nano spherical ferric phosphate as well as nano ferric phosphate prepared by the method, lithium ferric phosphate and a lithium battery. The method comprises the following steps: mixing: dropwise adding a mixed solution consisting of a phosphorus source compound solution and an oxidant solution into a soluble ferrous compound solution, adding a nano spherical control agent, and stirring and mixing; reacting: stirring at 50 to 100 DEG C under a refluxing condition, and reacting for 5 to 10 h; filtering: magnetically filtering the mixed solution after the reaction by adopting a high magnetic filter, press filtering the filtered solution, and obtaining a ferric phosphate crude product; and calcining: calcining for 24h at 650 to 850 DEG C under the protection of inert gas, and cooling to obtain a final ferric phosphate product. By adopting the method, the morphology of the ferric phosphate product can be controlled, and the performance of the lithium ferric phosphate can be improved.

Description

technical field [0001] The invention belongs to the technical field of preparation of new energy materials, in particular to a method for LiFePO 4 The preparation method of the nano-spherical iron phosphate of the prepared precursor raw material and the nano-iron phosphate, lithium iron phosphate and lithium battery prepared by the method. Background technique [0002] Lithium (sub)iron phosphate is an important cathode material for lithium batteries. It has a voltage of 3.5V and a theoretical capacity of 170mAh / g. Compared with lithium cobalt batteries, it is not only temperature resistant, but also has higher safety. Inexpensive lithium iron phosphate (LiFePO 4 ) compounds are attracting attention as positive electrode active materials for lithium secondary batteries. With the development of electric vehicles, the research on their preparation technology and morphology control methods has been developed rapidly. Among many materials for the preparation of lithium iron ph...

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Problems solved by technology

Among the obtained industrialization results, the post-treatment of nano-scale spherical iron phosphate obtained by phosphoric acid has a good effect by controlling the pH and aging, but the outstanding defect of this method is that it takes a long time and takes 2-3 days. time, affecting productivity

For example, the patent application number 201080011745.8 uses phosphoric acid and citric acid to control together. This method is not only time-consuming and affects production efficiency, but also because phosphoric acid is prone to have multi-level anions, such as: dihydrogen phosphate, monophosphate A variety of anions such as hydrogen radicals and phosphate radicals lead to complex components. During the precipitation process, oxides, hydroxide compounds, and precipitates of different grades of phosphate radicals will be included. These inclusions will affect the quality of iron phosphate and lead to the preparation of lithium iron phosphate materials. The purity is affected, which in turn affects the performance of the cathode material lithium iron phosphate

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