A kind of preparation method of high-pressure lithium ion battery positive electrode material lithium iron phosphate

Abstract

The invention provides a preparation method of a high compaction lithium ion battery positive pole material lithium iron phosphate. The method comprises the following steps: (1) mixing a lithium source, a high compaction iron source, a phosphorus source and solvent, then adding doped metal oxide and dispersing agent, further mixing, finally adding a carbon source, mixing, and performing dispersion and drying treatment on the uniformly mixed slurry to obtain solid powder particles; (2) performing gas flow pulverization on the solid powder particles; and (3) putting the pulverized materials in a revolving furnace with an inert gas protective atmosphere, performing heat treatment, naturally cooling the materials, then transferring into a high-temperature sintering furnace with an inert gas protective atmosphere, performing high-temperature heat treatment, naturally cooling, screening, and performing gas flow classification to obtain the high compaction density lithium iron phosphate, wherein the high compaction iron source is a Fe3O4 and Fe2O3 mixture of which the compaction density is no less than 3.6g / cm<3>. According to the preparation method provided by the invention, primary spray granulation is adopted, the process is simple, the process parameters are easy to control, and the process stability is favorable; and the compaction density of the lithium iron phosphate material prepared by the preparation method can be up to 2.7g / cm<3> or above.

Description

technical field [0001] The invention relates to a preparation method of lithium iron phosphate, in particular to a preparation method of lithium iron phosphate used as a positive electrode material of a lithium ion battery, and more particularly to a preparation method of lithium iron phosphate, a high-pressure lithium ion battery positive electrode material. Background technique [0002] As a new generation of green high-energy batteries, lithium-ion batteries are widely used due to their advantages such as high voltage, high energy density, good cycle performance, small self-discharge, no memory effect, and wide operating temperature range. [0003] application. Lithium iron phosphate is a new generation of lithium-ion battery cathode material, because of its low price, high theoretical capacity (about 170mAh / g), stable working voltage, non-toxic and environmentally friendly, stable structure, good safety, good thermal stability and long life The cycle life has become a h...

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Problems solved by technology

[0005] The Chinese patent application with the application number CN201110009020.1 discloses a method for preparing a high-capacity and high-compact-density lithium iron phosphate material, which includes (1) adding a lithium source, Fe 3+ Source, phosphate, dopant and organic carbon source are mixed, then spray granulation, (2) prepare calcined product, (3) mix calcined product and inorganic carbon source, and then spray dry to obtain two Secondary spray powder, (4) heating the secondary spray powder under vacuum conditions or in a protective atmosphere, and sintering at a constant temperature; (5) passing the above-mentioned sintered semi-finished product through secondary ball milling or jet milling to obtain phosphoric acid Iron-lithium products; its application specification records that this method solves the defects of increased product cost, difficulty in coating and low compaction density of pole pieces caused by the use of divalent iron sources, and has low production cost, and the prepared pole pieces have processability, Good electrical conductivity and electrochemical performance, but this method adopts the secondary synthesis method to prepare lithium iron phosphate, the process is complicated and the process is long, and the iron source uses ordinary iron trioxide or iron oxyhydroxide, and the prepared lithium iron phosphate is compacted lower density

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