Method for preparing nanoscale lithium ferric manganese phosphate material by using co-crystallization method

Abstract

The invention relates to a method for preparing a nanoscale lithium ferric manganese phosphate material by using a co-crystallization method, which comprises the steps of mixing a selected manganese source, an iron source and a phosphorus source according to a ratio, regulating the pH value, performing oxidation treatment to obtain a required intermediate precipitate, and filtering and drying to obtain an intermediate with good morphology and ratio; and mixing and sanding the precursor with a lithium source and a carbon source to obtain mixed slurry with a required particle size, pre-treating the mixed slurry to obtain a carbon-doped early-stage product, and calcining and crushing the carbon-doped early-stage product under the protection of inert gas to obtain the lithium ferric manganese phosphate positive electrode material. According to the invention, the intermediate is synthesized in the uniformly mixed solution, the ratio of iron to manganese is easy to control, the consistency of products in large-scale production can be ensured, and the synthesized LMFP material has good morphology, consistency, stability and high rate performance.

Description

technical field [0001] The invention belongs to the technical field of new energy materials, and is a novel intermediate method for preparing lithium iron manganese phosphate, and the intermediate is used as a raw material to further prepare nanoscale lithium iron manganese phosphate material. Background technique [0002] With the development of new energy vehicles, the demand for rechargeable secondary batteries with high specific energy is increasing, and the performance requirements for products are also getting higher and higher. Since the appearance of rechargeable lithium-ion batteries in the 1990s, Due to the advantages of small size, light weight, no memory effect, fast charge and discharge speed, and no pollution, it has attracted much attention. Among them, lithium iron manganese phosphate battery has naturally entered people's field of vision as a lithium-ion battery with excellent performance. [0003] Lithium manganese phosphate battery has two discharge platfo...

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Problems solved by technology

[0005] Although LMFP has many advantages, in terms of large-scale application, lithium iron manganese phosphate cathode materials still need to solve the following problems: 1. It is necessary to improve the stability of Fe / Mn ratio, so as to ensure the consistency of products in large-scale production; 2. It is to control the morphology of nano-lithium iron manganese phosphate and the particle size of lithium iron manganese phosphate to improve the cycle life and compaction density; the third is to greatly improve the electrical conductivity of lithium iron manganese phosphate, so that the rate performance and low temperature performance can be improved. Simultaneous improvement; 4. It is necessary to solve the problem of impurity control in the production process of lithium iron manganese phosphate to prevent the possible safety problems caused by the precipitation of iron single substance; 5. It is necessary to strictly control the environment of the synthesis process to prevent the participation of oxygen and cause material oxidation

[0006] At present, most of the synthesis methods of lithium iron manganese phosphate are high-temperature solid-phase method, solvothermal method, sol-gel method, etc. The synthesized lithium iron manganese phosphate product has a large primary particle size and uneven distribution, which makes the coating of lithium iron manganese phosphate cathode material Cloth performance, gram capacity, etc. are limited

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