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Method for synthesizing spheroidal lithium phosphate

A technology of metallic lithium and phosphoric acid, applied in non-metallic elements, chemical instruments and methods, phosphorus compounds, etc., can solve the problems of single olivine phase, difficult to control conditions, difficult to obtain, etc., and achieve excellent cycle performance, low cost, energy The effect of less loss

Active Publication Date: 2006-08-23
QINGHAI TAIFENG XIANXING LITHIUM ENERGY TECH CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Ying Jierong et al. synthesized spherical precursor ferrous ammonium phosphate, and then obtained spherical lithium iron phosphate by sintering (CN200510002012.9, preparation method of high-density spherical lithium iron phosphate and lithium manganese iron phosphate). This method uses water The precursor is obtained by phase precipitation, the operation is complicated and the conditions are difficult to control
Bewlay, S.L et al. obtained spherical LiFePO by spray drying 4 (Bewlay, S.L et al Conductivity improvements to spray-produced LiFePO 4 by addition of a carbon source, Materials Letters, 58(11)1788-1791), but during the spraying process, due to the inevitable generation of ferric impurities at high temperatures, it is difficult to obtain a single olivine phase
If the conventional solid-phase method can be used to synthesize spherical, single-phase lithium metal phosphate salts, it will have great application prospects. However, there are no relevant reports in this regard.

Method used

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  • Method for synthesizing spheroidal lithium phosphate
  • Method for synthesizing spheroidal lithium phosphate
  • Method for synthesizing spheroidal lithium phosphate

Examples

Experimental program
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Embodiment 1

[0021] Will Li 2 CO 3 , FeC 2 o 4 2H 2 O, NH 4 h 2 PO 4 Mix evenly at a molar ratio of 0.55:1:1, add sugar with a molar ratio of 5% to lithium ions during mixing, and pyrolyze at 400° C. for 5 hours in a sealed tube furnace protected by nitrogen. After cooling, mix the intermediate product with 2 times the molar ratio of KCl, then sinter at 760°C for 3 hours, cool naturally, wash the initial product with deionized water, then wash with ethanol, filter and dry under vacuum at 100°C to obtain lithium iron phosphate granular products.

[0022] The obtained lithium iron phosphate product has an olivine structure with a tap density of 1.52g cm -3 . Adopt Cu target Kα radiation, λ=0.15406nm, obtain the X-ray diffraction pattern of this product, as figure 1 shown. Through field emission scanning electron microscopy, it can be seen that the lithium iron phosphate particles are spherical or spherical, with a diameter of 2-4 μm, such as figure 2 shown. The cyclic voltammet...

Embodiment 2

[0024] Will Li 2 CO 3 , FeC 2 o 4 2H 2 O, (NH 4 ) 2 HPO 4 Mix evenly at a molar ratio of 0.51:1:1, add citric acid with a molar ratio of 5% to lithium ions during mixing, and pyrolyze in a sealed tube furnace at 300°C for 12 hours, protected by nitrogen. After cooling, the intermediate product was mixed with 4 times the molar ratio of KCl, then sintered at 760°C for 10 hours, cooled naturally, the initial product was washed with deionized water, then with ethanol, filtered and dried under vacuum at 100°C. Such as image 3 As shown, the obtained product has an olivine structure, spherical particles, a diameter of 5-6 μm, and a tap density of 1.64 g cm -3 , the first discharge capacity is 121.3mAh·g -1 .

Embodiment 3

[0026] LiOH·H 2 O, NH 4 FePO 4 Mix evenly at a molar ratio of 1.2:1, and pyrolyze in a sealed tube furnace at 350°C for 24 hours, protected by nitrogen. After cooling, mix the intermediate product with 1 times the molar ratio of K 2 CO 3 Mix, then sinter at 900°C for 0.5 hour, cool naturally, wash the initial product with deionized water, then with ethanol, filter and dry under vacuum at 100°C. The obtained product has an olivine structure, the particles are spherical, the diameter is 5-7μm, and the tap density is 1.54g cm -3 , the first discharge capacity is 120.6mAh·g -1 .

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Abstract

The present invention provides process of synthesizing spherical or spheriodal lithium phosphate. The compounds of lithium ion, transition metal ion and phosphate radical ion are mixed, ground and pyrolyzed in inert atmosphere to obtain the intermediate product; the intermediate product is mixed with certain amount of melting alkali salt and sintered at high temperature to obtain initial product; and the initial product is washed, filtered and dried to obtain spherical or spheriodal lithium phosphate grains of diameter 1-5 microns, with the grain size being controllable by means of the synthesis conditions. The process has short sintering time, low power consumption, and the spherical or spheriodal lithium phosphate product has small specific surface area, excellent processing performance, great tap density, high energy density and high safety, and may be used widely in power battery for electrically driven tool, electric bicycle, etc.

Description

technical field [0001] The invention relates to the field of lithium ion batteries, in particular to a method for preparing a spherical lithium metal phosphate electrode material. technical background [0002] As a new cathode material for lithium-ion batteries, LiMPO 4 Homologs especially LiFePO 4 It has received extensive attention and in-depth research (A.K.Padhi, K.S.Nanjundaswarmy, J.B.Goodenough, J.Electrochem.Soc.144(1997)1184). LiFePO 4 With a theoretical capacity of 170mAh / g, the actual capacity can exceed 160mAh / g, which is higher than commercial LiCoO 2 To be higher, the discharge platform is about 3.4V, than LiCoO 2 slightly lower. However, it has a wide range of sources of raw materials, low cost, high safety, and environmental friendliness, and is especially suitable for batteries for various high-power electrical appliances and power batteries for automobiles. The disadvantage is that the electronic conductivity is relatively low (~10 -8 S / cm), the larg...

Claims

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Application Information

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IPC IPC(8): C01B25/45
Inventor 倪江锋周恒辉陈继涛张新祥
Owner QINGHAI TAIFENG XIANXING LITHIUM ENERGY TECH CO LTD
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