A kind of preparation method of lithium iron manganese phosphate lithium battery cathode material

Abstract

The invention discloses a preparation method for a lithium battery positive material LiMn<1-x>Fe<x>PO4. The preparation method comprises the following steps of: dissolving and uniformly mixing a water-soluble manganese source compound, an iron source compound, a phosphate source compound, a lithium source compound and a chelating agent citric acid according to a sequence; adding a high-boiling point compound dimethylsulfoxide (DMSO); introducing a protective gas for protection; heating the mixture to obtain a product LiMn<1-x>Fe<x>PO4; mixing the product with an appropriate amount of carbon source; and sequentially grinding, heating and calcining in the protection of an inert gas to obtain the final product LiMn<1-x>Fe<x>PO4 / C material. The preparation method is carried out in a simple reaction kettle, a certain amount of the high-boiling point compound is added and mixed with water to serve as a reaction solvent, thus, the boiling point of the whole reaction system is increased, the reaction energy barrier is reduced, and the dynamic behavior of liquid-phase reaction is improved.

Description

technical field [0001] The invention relates to a method for preparing lithium iron manganese phosphate lithium iron manganese phosphate (LiMn 1−x Fe x PO 4 ), especially a method for preparing lithium iron manganese phosphate lithium battery cathode material, which belongs to the technical field of new energy material preparation. Background technique [0002] LiMnPO 4 with LiFePO 4 Same, it is a low-cost, safe and environmentally friendly lithium battery cathode material, because it has a higher ratio than LiFePO 4 The higher energy density of about 20% has attracted the attention of more researchers. However, due to its low electronic conductivity and ionic conductivity, it is far from meeting the requirements of utilization. In LiMnPO 4 In, Li + The diffusion of LiMnPO is mainly through the one-dimensional channel parallel to the b axis. During the deintercalation process of lithium ions, LiMnPO 4 To experience LiMnPO 4 to MnPO 4 phase transition. [0003] LiM...

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Problems solved by technology

[0009] Among these methods, the high-temperature solid-state reaction method is the most commonly used method, but this synthesis method has a long reaction time, cumbersome operation, low efficiency, and large energy consumption, and the particle size distribution of the final product obtained is not good. Uniform, prone to agglomeration and other phenomena, and the specific capacity of the obtained product is often not high;

[0010] Although the preparation process of the hydrothermal method is relatively simple, the obtained phase is uniform and the particle size is small, but it is limited to the preparation of small particles, and in the hydrothermal process, ions are prone to mix and match. If you want to reach the mass production level , will be subject to many restrictions, especially the high temperature and high pressure environment it requires, which is difficult to realize. In addition, the design and manufacture of high temperature and high pressure reaction vessels are also difficult and expensive

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