Preparation method of lithium iron phosphate, lithium iron phosphate and lithium ion battery

Abstract

The invention provides a preparation method of lithium iron phosphate, lithium iron phosphate and a lithium ion battery, and relates to the technical field of lithium ion batteries. The preparation method comprises the following steps: mixing an iron source, a phosphorus source, a lithium source and a carbon source, calcinikng, grinding, drying, and then carrying out calcinations again so as to obtain lithium iron phosphate. By adopting the specific working procedures, the particles of prepared and obtained lithium iron phosphate are similarly spherical, the particle size is in a micrometer or nanometer level, the granularity is uniform and controllable, and a uniform and firm carbon cladding layer is formed on the surface of lithium iron phosphate more easily through the similarly spherical shape, so that a complete electric conduction network can be formed, the electric conductivity of lithium iron phosphate is obviously improved, and the electrochemical performance of lithium iron phosphate is improved. The invention also provides lithium iron phosphate obtained by adopting the preparation method, lithium iron phosphate is similarly spherical, the granularity is uniform and controllable, and the carbon cladding layer on the surface of lithium iron phosphate is uniform and firm, and the complete electric conduction network can be formed, so that lithium iron phosphate has good electrochemical performance.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a preparation method of lithium iron phosphate, lithium iron phosphate and lithium ion batteries. Background technique [0002] Lithium-ion batteries mainly include three parts: positive electrode, electrolyte and negative electrode. Among them, the cathode material of lithium-ion battery is the key factor that determines the electrochemical performance, safety performance, energy density and price cost of the battery. At present, there are many cathode materials for lithium-ion batteries, such as cobalt-based cathode materials, nickel-based cathode materials, manganese-based cathode materials, and lithium iron phosphate cathode materials. [0003] Among them, lithium iron phosphate (LiFePO 4 ) The theoretical capacity of the positive electrode material is 170mAh / g, the reversible charge-discharge specific capacity is high, and at the same time, it has the advanta...

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Problems solved by technology

However, due to the limitation of its own structure, the ionic conductivity and electronic conductivity of lithium iron phosphate are low, which is only suitable for charging and discharging at low current density, and the specific capacity decreases when charging and discharging at high rates, which limits the application of this material.

[0004] At present, a large number of researches on the modification of lithium iron phosphate have been carried out at home and abroad to improve the conductivity of lithium iron phosphate, mainly including the preparation of nano-scale LiFePO 4 , Preparation of porous LiFePO 4 , metal ion doping and other methods, however, the lithium iron phosphate prepared by the above method still has a lot of room for improvement in electronic conductivity and ion conductivity, and at the same time, the particle morphology of the currently prepared lithium iron phosphate is irregular, and Uneven particle size distribution

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