Compound lithium iron phosphate material and preparing method thereof, positive electrode piece and lithium ion battery

Abstract

The invention relates to a compound lithium iron phosphate material and a preparing method thereof, a positive electrode piece and a lithium ion battery, and belongs to the technical field of lithiumion batteries. The compound lithium iron phosphate material is prepared from, by mass, 75-85% of lithium iron phosphate, 10-25 parts of nickel cobalt lithium manganate, 1-2% of carbon nano tube and 1-2% of conductive black. The prepared compound lithium iron phosphate material is a high high-energy density compound lithium iron phosphate material, lithium iron phosphate, nickel cobalt lithium manganate, carbon nano tube and conductive black fill one another, the porosity among materials is lowered, and the compaction density of the materials is increased.

Description

technical field [0001] The invention relates to a composite lithium iron phosphate material and a preparation method thereof, a positive pole piece and a lithium ion battery, belonging to the technical field of lithium ion batteries. Background technique [0002] In recent years, due to the advantages of high working voltage, high energy density, no memory effect, long cycle life, and no pollution, lithium-ion batteries have been more and more widely used in consumption, power, energy storage and special batteries. With the two-wheel drive of capital, the new energy automobile industry and the energy storage field have higher and higher requirements for battery energy density. Although the energy density of ternary batteries is much higher than that of lithium phosphate batteries, their prices are more expensive, and their cycle performance and safety performance are relatively high. Difference. At present, lithium iron phosphate batteries in the new energy industry are sti...

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Problems solved by technology

[0004] The Chinese invention patent with the application publication number CN101388459A discloses a preparation method of a lithium iron phosphate composite positive electrode material. The lithium iron phosphate obtained by the high-temperature solid-phase synthesis method is mixed with an additional positive electrode material and a cosolvent, and then the mixture is heated for a second time. Granulation treatment, the additional positive electrode material is at least one of lithium cobaltate, lithium manganate, lithium nickelate or lithium nickel cobalt manganate, and the flux is NaPO 3 F and LiPO 3 At least one of F, the secondary granulation treatment is carried out under a protective atmosphere at 100-900°C, and the secondary granulation treatment time is 12h-48h; the preparation method of the lithium iron phosphate composite cathode material disclosed in this patent requires The secondary treatment takes a long time and needs to add a flux. The flux is conducive to the secondary growth of lithium iron phosphate particles, but the flux will also make the positive electrode material doped with impurities such as P, which affects the performance of the positive electrode material.

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