Method for uniformly coating carbon on nano lithium iron phosphate

Abstract

The invention discloses a method for uniformly coating carbon on nano lithium iron phosphate, which is characterized by comprising the following steps of: 1) weighting soluble ferrous salt and phosphoric acid according to a proportion, dissolving the ferrous salt and the phosphoric acid in deionized water, adding a complexing agent into the mixture, and slowly adding lithium salt solution into the mixture under continuous stirring; 2) continuously stirring the solution in an oil bath until a green precipitate is generated, and performing suction filtration and washing to obtain a solid product; 3) drying the solid product in a vacuum drying oven, and performing ball milling on the dried solid product to obtain precursor powder; 4) dissolving the precursor powder and nano amorphous carbon in the deionized water, uniformly dispersing and mixing the precursor powder and the nano amorphous carbon, and drying the mixture to obtain a nano carbon-coated precursor; and 5) grinding and breaking the nano carbon-coated precursor, and sintering to obtain the uniform carbon-coated nano lithium iron phosphate. By adopting method, the nano-size carbon is fully dispersed in the solution and is uniformly coated on lithium iron phosphate granules through the surface acting force among nano granules, and the transmission rate of ions and electrons, thereby improving the electric conductivity of the nano lithium iron phosphate.

Description

Technical field [0001] The invention relates to a preparation technology of a lithium ion battery cathode material, in particular to a method for uniform carbon coating of nano lithium iron phosphate. Background technique [0002] In lithium-ion batteries, the cathode material is the most important component and the key to determining the performance of lithium-ion batteries. Lithium iron phosphate materials have the characteristics of good safety, excellent cycle performance, environmental friendliness, and a wide range of raw materials. Among them, lithium, iron, and phosphorus are all elements with abundant reserves on the earth, especially the iron-based materials have a wide range of raw materials and low prices. Recognized as the preferred cathode material for the new generation of lithium-ion batteries, it has become the key research and development direction of major developed countries in the world today. Moreover, due to its stability at high temperatures and the elect...

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Problems solved by technology

6. No memory effect

[0004] Moreover, most of the preparation of lithium iron phosphate positive electrode materials is mostly prepared by solid phase sintering, and then it is ball milled and mixed with carbon for carbon coating to increase the conductivity of lithium iron phosphate. In fact, solid The particle size of the lithium iron phosphate prepared by the phase method is relatively large, and the carbon cannot be directly mixed and evenly coated on the outside of the lithium iron phosphate particles. Secondly, even if the lithium iron phosphate with a smaller particle size is obtained by crushing or other methods, the carbon cannot Unable to fully cover around lithium iron phosphate particles

Its conductivity is still limited, and on the one hand, the particle size obtained by the crushing method is uneven, and the efficiency is low, and secondly, it is easy to damage the structure of the material, which fundamentally determines its poor conductivity.

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