Lithium-doped boron phosphate-modified carbon-coated LMFP positive electrode material and preparation method thereof

A technology of carbon-coated lithium manganese iron phosphate and lithium manganese iron phosphate, which is applied in the direction of battery electrodes, structural parts, electrical components, etc., can solve the problems of material specific capacity decrease, battery flatulence, and electrode sheets are not easy to dry, and achieve the purpose of inhibiting dissolution , Guaranteed capacity, and improved cycle stability

Active Publication Date: 2018-01-23
中科致良新能源材料(浙江)有限公司
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Problems solved by technology

However, due to the smaller size of lithium manganese iron phosphate particles, the gap between the particles is too small when it is made into a battery, it is difficult for the electrolyte to completely infiltrate, and it is difficult for lithium ions to reach the surface of some lithium manganese iron phosphate particles, resulting in material ratio Decrease in capacity; at the same time, lithium manganese iron phosphate particles have a larger specific surface area, so it is easier to absorb moisture, the electrode sheet is not easy to dry, and it is easy to cause problems such as battery flatulence
In addition, the charging potential of lithium manganese iron phosphate particles generally needs to be above 4.3V, which may cause the dissolution of some manganese ions, resulting in a decrease in cycle performance.

Method used

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  • Lithium-doped boron phosphate-modified carbon-coated LMFP positive electrode material and preparation method thereof
  • Lithium-doped boron phosphate-modified carbon-coated LMFP positive electrode material and preparation method thereof
  • Lithium-doped boron phosphate-modified carbon-coated LMFP positive electrode material and preparation method thereof

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preparation example Construction

[0025] The present invention also discloses a preparation method of a carbon-coated lithium manganese iron phosphate positive electrode material modified by lithium-doped boron phosphate, comprising the following steps:

[0026] S1, dissolving boric acid and ammonium dihydrogen phosphate in an aqueous solution in proportion to form a first solution, while dissolving lithium hydroxide in another part of an aqueous solution to form a second solution, the moles of lithium hydroxide, boric acid, and ammonium dihydrogen phosphate The ratio is x:(1-x / 3):1, x=0.05-0.13; the concentration range of ammonium dihydrogen phosphate in the first solution is 0.01-0.1mol / L; the concentration of lithium hydroxide in the second solution The range is 0.002-0.2mol / L;

[0027] S2, mixing the carbon-coated lithium manganese iron phosphate particles with the first solution obtained in step S1 under the condition of ultrasonic dispersion while stirring, the carbon-coated lithium manganese iron phosph...

Embodiment

[0034] Preparation of 2wt% lithium-doped boron phosphate modified carbon-coated lithium manganese iron phosphate positive electrode material: 0.1147g of boric acid and 0.2171g of ammonium dihydrogen phosphate were dissolved in 30ml of deionized water, stirred at room temperature to form the first solution, and 0.004g of Lithium hydroxide was dissolved in 5ml deionized water, and stirred at room temperature to form the second solution; 9.8g of carbon-coated lithium manganese iron phosphate was weighed and poured into the first solution, and ultrasonically dispersed for 15 minutes while stirring, and then placed at 90 ℃ heating and stirring, slowly drop the second solution into it, continue heating and stirring to evaporate the water to dryness, and obtain block Li x B 1-x / 3 PO 4 (x=0.05) a mixture of a precursor and lithium manganese iron phosphate material; transfer the precursor to a tube furnace, slowly raise the temperature to 110°C for 2h under a nitrogen atmosphere, then...

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Abstract

The invention discloses a lithium-doped boron phosphate-modified carbon-coated LMFP positive electrode material and a preparation method thereof. The particle sizes of LMFP primary particles are smaller than 80nm; and a carbon coating layer which is 0.1-2nm in thickness is formed on the surface of each LMFP primary particle. The LMFP primary particles are reunited to form carbon-coated LMFP secondary particles of which the particle sizes are 10-50 microns; and gaps between the primary particles in the carbon-coated LMFP secondary particles are filled with lithium-doped boron phosphate. The lithium-doped boron phosphate is a lithium-ion conductor, so that the LMFP primary particles in the secondary particles can be provided with a lithium-ion transport channel, and development of the capacity of active materials in the secondary particles is ensured; and meanwhile, lithium-doped boron phosphate modification is surface coating on the LMFP primary particles, so that dissolution of manganese ions can be suppressed and the cycling stability of the LMFP material is improved.

Description

technical field [0001] The invention relates to the technical field of lithium-ion battery cathode materials, in particular to a carbon-coated lithium manganese iron phosphate cathode material modified with lithium-doped boron phosphate and a preparation method thereof. Background technique [0002] The main reason that restricts the large-scale application of lithium iron phosphate to battery materials is its poorer electronic conductivity (<10 -10 S cm -1 ) and lithium ion diffusion rate, resulting in extremely low charge and discharge capacity and poor battery rate performance. In order to improve lithium ion transmission efficiency and electron conduction efficiency, the primary particle size of lithium manganese iron phosphate must be reduced to a scale smaller than 80 nanometers, which is much smaller than the diameter of traditional lithium iron phosphate particles close to 200 nanometers. This reduction in primary particle diameter brings new problems while enab...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/58H01M4/62H01M10/0525
CPCY02E60/10
Inventor 卢威高珊陈朝阳卞果
Owner 中科致良新能源材料(浙江)有限公司
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