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LiFePO4 cathode material based on P site doped and preparation method thereof

A lithium iron phosphate and cathode material technology, applied in chemical instruments and methods, phosphorus compounds, battery electrodes, etc., can solve the problems of low volume energy density, poor conductivity, and low bulk density of batteries, and achieve good rate discharge performance, crystallization The effect of good performance and wide application prospects

Inactive Publication Date: 2007-09-19
XIAMEN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Pure LiFePO 4 The material has its own shortcomings, manifested in: (1) low electronic conductivity
This leads to poor rate charge and discharge performance, which is only suitable for low current working conditions and cannot be adapted to work under high current conditions, which is not conducive to being used in power-type power batteries; (2) Low stacking density
This leads to the low volumetric energy density of batteries made of this material, and the difficulty in processing pole pieces, which affects the practical application of this material.
[0005] Currently, for LiFePO 4 A lot of work has been done on the above shortcomings of materials. In order to solve the problem of poor conductivity, methods such as surface coating (such as carbon coating, etc.) and element doping (Li site, Fe site) have been proposed; for the problem of low packing density, proposed crystal form controlled growth

Method used

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  • LiFePO4 cathode material based on P site doped and preparation method thereof
  • LiFePO4 cathode material based on P site doped and preparation method thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0018] Example 1: Add 8.34g of ferrous sulfate FeSO 4 ·7H 2 O, 3.45g ammonium dihydrogen phosphate NH 4 H 2 PO 4 Mix, add to the agate ball mill tank, add 5ml of absolute ethanol as the ball mill solvent, seal and mix on a planetary ball mill at 500rpm for 8h, dissolve and filter with deionized water after discharging, and wash with deionized water for 3~4 The concentration of 1mol / L barium nitrate Ba(NO 3 ) 2 Sulfate ion SO cannot be detected in the solution 4 2- . The filtered product was vacuum dried at 60°C for 8 hours to obtain an intermediate product. Put 3.06g lithium acetate CH 3 COOLi·2H 2 O and the intermediate product were added to the ball milling tank, 5ml of absolute ethanol was added as the ball milling solvent, and after sealing, it was mixed on a planetary ball mill at 500rpm for 10h. After the material was discharged, it was vacuum dried at 80℃ for 2h, and then heated at 10ml / s. In a nitrogen-hydrogen mixed gas atmosphere, the temperature is increased to 600°C a...

Embodiment 2

[0021] Example 2: The 16.80g ferrous acetate Fe(CH 3 COO) 2 ·2H 2 O, 11.93g ammonium phosphate (NH 4 ) 3 PO 4 Mix, add to the agate ball mill tank, add 5ml of absolute ethanol as the ball mill solvent, seal and mix on a planetary ball mill at 500rpm for 8h, dissolve and filter with deionized water after discharging, and wash with deionized water for 3~4 all over. The filtered product was vacuum dried at 80°C for 6 hours to obtain an intermediate product. 2.96g lithium carbonate Li 2 CO3 Add 5ml of absolute ethanol as the ball milling solvent with the intermediate product into the ball milling tank. After sealing, continue to mix on the planetary ball mill at 500rpm for 10h. After the material is discharged, vacuum dry at 80℃ for 2h, and then in 15ml / s of nitrogen. In the atmosphere, the temperature rises to 700°C at a heating rate of 5°C / min, the temperature is kept for 5 hours, and the furnace is lowered to room temperature to obtain lithium iron phosphate LiFePO 4 Powder, denote...

Embodiment 3

[0022] Example 3: Add 16.80 g of ferrous acetate Fe(CH 3 COO) 2 ·2H 2 O, 11.33g ammonium phosphate (NH 4 ) 3 PO 4 And 0.60g tin dioxide SnO 2 Mix, add 5ml of acetone as the ball milling solvent to the agate ball milling tank, seal and mix on a planetary ball mill at a speed of 500 rpm for 8 hours, dissolve and filter with deionized water after discharging, and wash with deionized water for 3 to 4 times. The filtered product was vacuum dried at 100°C for 6 hours to obtain an intermediate product. 3.10g lithium carbonate Li 2 CO 3 Add 5ml of acetone as the ball milling solvent with the intermediate product into the ball milling tank. After sealing, continue mixing on the planetary ball mill at 500 rpm for 10 hours. After the material is discharged, it is vacuum dried at 80°C for 2 hours, and then mixed with 10ml / s of nitrogen and hydrogen. In a gas atmosphere, the temperature is increased to 700°C at a heating rate of 5°C / min, and kept at this temperature for 5 hours, and then dropp...

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Abstract

Disclosed is a phosphorus-doped lithium iron phosphate positive electrode material and a preparation method of the same, which relates to a positive electrode materials of lithium ion batteries. The present invention provides a phosphorus-doped lithium iron phosphate positive electrode material of lithium ion batteries with higher charge-discharge capacity, excellent multiplying power performance and cycle performance, and a preparation method of the same. The positive electrode material has a formula of LiyFe(P1-xMx)O4, wherein M is doping element of Ge, Sn, Se, Te or Bi. The preparation method comprises the steps of mixing the ferrite and phosphate with dopant; adding at least one of the water, alcohol, acetone serving as ball mill solvent; scrubbing and filtrating after ball milling; vacuum drying the filtration product to obtain the intermediate product which is mixed with lithium salt; adding ball mill solvent to ball mill again; drying the product and then heating calcining in the presence of inert gas or reducing atmosphere to obtain doping type lithium iron phosphate LiyFe(P1-xMx)O4 powder.

Description

Technical field [0001] The invention relates to a lithium ion battery positive electrode material, in particular to a lithium iron phosphate positive electrode material based on phosphorus site substitution (doping) and a preparation method thereof. Background technique [0002] At present, the production of small-capacity lithium batteries in my country, such as mobile phone batteries and notebook computer batteries, has basically been saturated, but large-capacity power lithium-ion batteries have still not entered the market. Traditional small lithium-ion batteries have been dominated by lithium cobalt oxide cathode materials since their inception. Due to disadvantages such as poor safety and high price of lithium cobalt oxide, they cannot truly meet the needs of the lithium-ion power battery industry. Although the price of spinel lithium manganese oxide cathode material is low and the rate performance is good, the defect of poor high-temperature cycle stability has not been so...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B25/45H01M4/58
CPCY02E60/10
Inventor 杨勇张忠如朱昌宝
Owner XIAMEN UNIV
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