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A kind of lithium iron phosphate cathode material and preparation method thereof

A technology for lithium iron phosphate and positive electrode materials, applied in chemical instruments and methods, phosphorus compounds, battery electrodes, etc., can solve the problems of low ion diffusion speed, one-dimensional ion conduction, poor cycle performance and rate performance, etc. No agglomeration, excellent low temperature performance

Active Publication Date: 2015-10-14
QINGHAI TAIFENG XIANXING LITHIUM ENERGY TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] The purpose of the present invention is to provide a lithium iron phosphate positive electrode material with excellent low temperature performance and its preparation method, to overcome the technical defects of low ion diffusion rate and one-dimensional ion conduction in the existing lithium iron phosphate composite material, and to solve the problem of existing phosphoric acid The problem of poor cycle performance and rate performance of lithium iron cathode materials

Method used

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  • A kind of lithium iron phosphate cathode material and preparation method thereof
  • A kind of lithium iron phosphate cathode material and preparation method thereof
  • A kind of lithium iron phosphate cathode material and preparation method thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0036] Weigh 1.68g of lithium carbonate, 8.03g of ferrous oxalate dihydrate and 5.16g of phosphoric acid with a concentration of 85%, wherein the molar ratio Li:Fe:P=1.02:1:1, fully mixed and dried at 100°C for 3 hours A dry material is obtained. A dry material was calcined in a nitrogen atmosphere at 500° C. for 8 hours, and cooled with the furnace to obtain 7.04 g of a calcined material. Add the first-calcined material, 0.11g of lithium carbonate, 0.30g of ferrous oxalate dihydrate and 0.17g of phosphoric acid (Li:Fe:P=2:1:2) with a concentration of 85% into 50ml of acetone, and mix them thoroughly at 110 Drying at °C for 2.5 hours gave a dry material. The two-calcined material was calcined in a nitrogen atmosphere at 600° C. for 8 hours, and cooled with the furnace to obtain 7.22 g of the two-calcined material. The dioxane material and 0.36 g of glucose were added to 50 ml of acetone, mixed thoroughly and then dried at 120° C. for 2 hours to obtain a tri-dry material. The ...

Embodiment 2

[0040] Weigh 42.16g of lithium hydroxide, 77.14g of ferric oxide, 111.14g of ammonium dihydrogen phosphate and 3.29g of tetrabutyl titanate into 700ml of deionized water, wherein the molar ratio Li:Fe:P:Ti=1.04:1 :1:0.01, mixed thoroughly and dried at 90°C for 5 hours to obtain a dry material. A dry material was calcined in an argon atmosphere at 600° C. for 4 hours, and cooled with the furnace to obtain 152.43 g of a calcined material. Add the first-calcined material, 2.10g lithium hydroxide, 2.00g ferric oxide and 5.76g ammonium dihydrogen phosphate (Li:Fe:P=2:1:2) into 700ml deionized water, mix well and set at 150°C Drying was carried out for 2 hours to obtain a dry material. Calcined the two-calcined material in an argon atmosphere at 500° C. for 9 hours, and cooled with the furnace to obtain 157.61 g of the two-calcined material. Add the two-calcined material and 12g of rock sugar into 700ml of deionized water, mix well and dry at 120°C for 2 hours to obtain the three-...

Embodiment 3

[0042] Weigh 53.52g of anhydrous lithium acetate, 178.20g of ferric oxalate pentahydrate, 101.04g of diammonium hydrogen phosphate and 0.78g of aluminum oxide and add them to 1000ml of acetone, wherein the molar ratio Li:Fe:P:Al=1.06:1: 1:0.02, mixed thoroughly and dried at 200°C for 2 hours to obtain a dry material. A dry material was calcined in a nitrogen atmosphere at 550° C. for 6 hours, and cooled with the furnace to obtain 120.70 g of a calcined material. Add the first-calcined material, 1.96g of anhydrous lithium acetate, 3.46g of ferric oxalate pentahydrate and 3.93g of diammonium hydrogen phosphate (Li:Fe:P=2:1:2) into 1000ml of acetone, mix well and set at 160°C Drying was carried out for 2 hours to obtain a dry material. Calcined the two-dried material in a nitrogen atmosphere at 700° C. for 5 hours, and cooled with the furnace to obtain 123.61 g of the two-calcined material. Add the two-burned material and 12g of asphalt into 1000ml of acetone, mix well and dry ...

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Abstract

The invention relates to an LFP (lithium iron phosphate) positive electrode material with excellent low-temperature property. The LFP positive electrode material comprises LFP particles, and lithium iron pyrophosphate covering the LFP particles. The preparation method comprises the steps of fully mixing a Li-source compound, a Fe-source compound, a P-source compound and a compound containing doped metal M in a dispersing agent according to the molar ratio of X:1:1:Y, grinding and drying to obtain a dry material A, wherein X is not less than 1.02 and not greater than 1.10, and Y is not less than 0 and not greater than 0.05; heating the material A to obtain a sintered material B; adding B, the Li-source compound, the Fe-source compound and the P-source compound into the dispersing agent, grinding, and drying to obtain a dry material C; and heating the material C to obtain the LFP particles coated with lithium iron pyrophosphate. Furthermore, a carbon layer can be generated to improve the electron conductivity. The LFP positive electrode material provided by the invention is effectively improved in the low-temperature property and the rate capability.

Description

technical field [0001] The invention belongs to the technical field of cathode materials for lithium ion batteries, and in particular relates to a lithium iron phosphate material with excellent low-temperature performance used as an anode material for lithium ion secondary batteries and a preparation method thereof. Background technique [0002] Since the advent of lithium iron phosphate materials (Padhi AK, Nanjundaswamy KS and Goodenough JB, J. Electrochem. Soc. 1997, 144: 1188-1194), due to its low cost and environmental friendliness, it is now used as a cathode material for lithium-ion secondary batteries Has been widely used. The polyanion structure of lithium iron phosphate crystal has good stability. On the one hand, it makes the structure of the material stable and not easy to collapse during electrochemical charge and discharge, so that it has excellent performance in capacity retention and cycle performance; however, on the other hand, it also makes the material T...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/58C01B25/45
CPCY02E60/10
Inventor 张卫东周恒辉黄长靓
Owner QINGHAI TAIFENG XIANXING LITHIUM ENERGY TECH CO LTD
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