Preparation method of lithium iron phosphate composite coated by double carbon layers

Abstract

The invention discloses a preparation method of a lithium iron phosphate composite coated by double carbon layers. The preparation method comprises the following steps: step 1, evenly mixing an iron source, a phosphorus source and a lithium source at certain molar ratio into an ethanol solution to form a mixed solution, then adding and dissolving a carbon source into the mixed solution to form a first mixture, then adding an ordered mesoporous carbon into the first mixture, conducting ultrasonic treatment for a first preset time at the room temperature to form a second mixture; step 2, putting the second mixture into a container, conducting a hydrothermal reaction for a second preset time at a first preset temperature, cooling to form a third mixture, washing and drying the third mixture to prepare a carbon doped lithium iron phosphate composite; step 3, putting the carbon doped lithium iron phosphate composite into a container under the protection of nitrogen gas, calcining for a third preset time at a second preset temperature, cooling, taking out, alternatively washing with the deionized water and absolute ethyl alcohol sequentially for a plurality of times, and drying to obtain the lithium iron phosphate composite coated by the double carbon layers.

Description

【Technical field】 [0001] The invention relates to the technical field of battery cathode materials, in particular to a preparation method of a double carbon layer-coated lithium iron phosphate composite material. 【Background technique】 [0002] Lithium iron phosphate materials with an olivine structure are widely used as cathode materials for lithium batteries due to their good cycle performance, good stability, low price, and abundant resources. However, due to the lithium iron phosphate material with an olivine structure as the positive electrode material, the electronic conductivity and ion diffusion rate of lithium iron phosphate are significantly reduced at low temperature, and the capacity loss is serious at low temperature, which limits the lithium battery. Popularization and application in low temperature environment. At present, there are three main aspects to improve the low-temperature performance of lithium batteries prepared from lithium iron phosphate material...

AI Technical Summary

Problems solved by technology

Due to the particle size, microscopic morphology, crystal structure, type and content of doping and coating substances of lithium iron phosphate materials, it is difficult to achieve the desired effect through a single improvement method, such as carbon coating to improve lithium iron phosphate , it is difficult to obtain a uniform and complete carbon coating layer, and the carbon content of a single layer of carbon coating is low, and the electronic conductivity of the material is not ideal.

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