Flaky iron phosphate, and preparation method and application thereof

Abstract

The invention discloses flaky iron phosphate, and a preparation method and application thereof. The microscopic morphology of the flaky iron phosphate is a primary particle in a sheet shape with a thickness of 10 to 50 nm, a length of 100 nm to 3 [mu]m and a width of 100 nm to 3 [mu]m. The preparation method comprises the following steps of: weighing a ferrous ion solution and adding phosphoric acid and a crystal modifier; weighing a phosphorus salt solution and adding an oxidizing agent; carrying out mixing to obtain a mixed solution C, controlling the pH value of the mixed solution C to be 1.5-2.2, and carrying out a reaction to obtain pale yellow iron phosphate slurry; converting the iron phosphate slurry into white or pink-white iron phosphate slurry containing crystal forms under theconditions of stirring and heating, reducing a stirring speed by 20%-50% after the completion of the conversion, and carrying out ageing and heat preservation; performing solid-liquid separation, andcollecting a solid portion to obtain a crystalline iron phosphate precipitate; and washing the precipitate and then performing calcination to obtain the flaky iron phosphate. The iron phosphate of theinvention can be used for preparing lithium iron phosphate with high compaction density.

Description

technical field [0001] The invention relates to the field of new energy technology, in particular to a sheet-shaped iron phosphate and its preparation method and application. Background technique [0002] At present, lithium iron phosphate electrode materials have entered the stage of rapid industrialization and application promotion. Power and energy storage batteries made of lithium iron phosphate as the positive electrode also show good safety and cycle performance, and their application scale is gradually expanding. However, Future energy demands put forward higher energy density requirements for lithium iron phosphate power and energy storage batteries. [0003] As the precursor of lithium iron phosphate, the morphology and particle size distribution of iron phosphate have a great influence on the compaction density of lithium iron phosphate cathode. Therefore, it is of high application value to study the preparation of iron phosphate with controllable morphology. At p...

AI Technical Summary

Problems solved by technology

At present, the primary particles of commercial iron phosphate are spherical, and the secondary particles are porous honeycomb structure. The secondary particles further form soft aggregates without specific morphology. This kind of iron phosphate has more internal pores, which reduces the compaction density.

Iron phosphate is used as the skeleton of lithium iron phosphate. During the downstream wet grinding process of lithium iron phosphate, these internal porous iron phosphates are easily broken, resulting in too narrow particle size distribution of lithium iron phosphate, and a large number of pores between balls. If there is no Filling gaps with suitable small particle size balls will further reduce the compacted density of the material

In the preparation process of ferric phosphate with more internal pores, the ratio of wet material is relatively high when free water is removed to form ferric phosphate dihydrate, usually at 50m 2 / g or so, for this kind of ferric phosphate dihydrate with high porous ratio, most iron phosphate manufacturers melt the ferric phosphate through high temperature above 800℃ and prolong the sintering time, so that the specific ratio of anhydrous ferric phosphate is 1.5~3m 2 / g, to reduce the internal pores of iron phosphate, but this process leads to increased energy consumption, and at the same time, it will cause the material to sinter and agglomerate seriously, and the subsequent crushing process is difficult, which greatly reduces the production efficiency of the enterprise. The processing performance of iron phosphate has strict requirements on the preparation process of the subsequent positive lithium iron phosphate material. If the processing technology of the lithium iron phosphate manufacturer is not suitable, the iron phosphate prepared by using this iron phosphate will usually cause difficulty in discharging.

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