Method for producing lithium iron phosphate by solid-phase sintering of pure liquid-phase mixture

Abstract

The invention relates to the field of lithium ion battery positive electrode materials, in particular to a method for producing lithium iron phosphate through solid-phase sintering of pure liquid-phase mixed materials. The preparation method comprises the following steps: adding a proper amount of acid radical catching agent into a solution of soluble iron source, phosphorus source and lithium source according to a molar ratio of 1: 1: 1, carrying out spray drying to obtain a lithium iron phosphate precursor with uniformly mixed ion and molecule levels, and carrying out carbon source adding, grinding, high-temperature sintering, crushing and crushing by using a mature solid-phase sintering process to obtain the lithium iron phosphate positive electrode material. According to the method, ion molecule level uniform material mixing before solid-phase sintering is realized, the grinding and material mixing procedures which are high in cost and time consumption are omitted, and the batch stability and the battery performance of the sintered lithium iron phosphate are improved.

Description

technical field [0001] The invention belongs to the technical field of positive electrode materials for lithium ion batteries, in particular to a method for producing lithium iron phosphate by solid-phase sintering of pure liquid phase mixture. Background technique [0002] In 1997, Goodenough et al. first reported that lithium iron phosphate with olivine structure can be used as lithium battery, which has attracted extensive attention and a lot of research. It has a wide range of raw material sources, low cost, no environmental pollution, and good cycle performance. With the advantages of good thermal stability and outstanding safety performance, it is an ideal cathode material for power lithium-ion batteries. With the application of new energy vehicles and energy storage, its industry has shown an explosive growth trend. [0003] There are two main synthesis methods of lithium iron phosphate, solid phase method and liquid phase method. The biggest advantage of solid phase ...

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Problems solved by technology

Although the performance of lithium iron phosphate is improved by adding lithium titanate, it cannot fundamentally solve the problem of uniformity of solid phase mixing

[0008] CN100570930 discloses a method for preparing nanoscale lithium iron phosphate using the principle of co-precipitation method. The method uses iron powder lithium phosphate hydroxide to obtain a lithium iron phosphate precursor, and then uses solid-phase roasting to obtain lithium iron phosphate. This method can be compared with The mature mixing process of iron phosphate and lithium carbonate can get a better mixing effect, but because of the use of iron powder, which is an insoluble iron source, there is still no way to fundamentally solve the problem of uniformity of mixing

[0009] CN103560246B discloses a kind of method of full liquid phase mixing, spray granulation, pre-fired once, then carbon wrapping after grinding, spraying again, and then roasting to obtain lithium iron phosphate, but the method uses Fe(NO 3 ) 3 The iron source uses the characteristic that nitrate can be decomposed cleanly at high temperature, but in the process of decomposing nitrate, it will decompose a large amount of NO and NO2 highly toxic gases, and it is very corrosive, which is harmful to equipment and production personnel. There are major safety hazards

[0010] CN108461720A discloses a semi-solid phase mixing using an acidic chelating agent, without time-consuming and energy-consuming grinding process, effectively shortening the synthesis time, although the mixing effect of this method is much better than the traditional all-solid phase process, but far Far less than the mixing effect of pure liquid phase

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