Preparation of LiFePO4

A solution and iron salt technology, applied in chemical instruments and methods, phosphorus compounds, inorganic chemistry, etc., can solve the problems of complex steps and high preparation costs, and achieve the effects of simple steps, excellent performance and low price

Active Publication Date: 2008-12-24
杭州金马新能源科技有限公司
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  • Abstract
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  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] The purpose of this invention is to provide a LiFePO 4 The preparation method, which mainly solves the technical problems that the crystal shape of lithium iron phosphate existing in the prior art is granular, and post-heat treatment must be carried out in the preparation process, the steps are relatively complicated, and the preparation cost is relatively high.

Method used

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  • Preparation of LiFePO4
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Examples

Experimental program
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Effect test

Embodiment 1

[0032] Embodiment 1: a kind of LiFePO of this example 4 The preparation method, its step is:

[0033] a. Add phosphorus-containing compound solution, surfactant, and carbon-coated carbon source to 10ml iron salt solution for hydrothermal synthesis; the iron salt solution is FeSO 4 , the phosphorus compound is H 3 PO 4 , the surfactant is PEG, the carbon-coated carbon source is sucrose; the molar ratio of Fe atom to P atom is 1:1, the molar ratio of Fe atom to surfactant is 1:1, and sucrose is 5% of FeSO4 mass.

[0034] b. Introduce nitrogen for 10 minutes, and then discharge the air;

[0035] c. Add 10ml of lithium salt solution, the lithium salt solution is LiOH, and the molar ratio of Fe atom to Li atom is 1: 2.5;

[0036] d. Introduce nitrogen for 10 minutes, control the pH value to 9.0, heat up to 180°C for hydrothermal treatment for 360 minutes;

[0037] e. Suction filtration, washing and drying to obtain pure-phase crystals of flaky or columnar LiFePO 4 finished pr...

Embodiment 2

[0042] Embodiment 2: a kind of LiFePO of this example 4 The preparation method, except that the molar ratio of Fe atoms and P atoms in step a is 1: 1.2, the rest of the steps are the same as in Example 1.

[0043] After the X-ray diffraction analysis of the obtained product, it is also LiFePO with pure phase, no impurities, and good crystallinity. 4 The sample has no change in the scanning electron microscope compared with Example 1, and its electrochemical behavior shows that its first discharge capacity increases.

[0044] The X-ray diffraction data of this embodiment product see figure 1 in b.

[0045] The first discharge curve of this embodiment is shown in Figure 5 in b.

Embodiment 3

[0046] Embodiment 3: a kind of LiFePO of this example 4 The preparation method, except that the molar ratio of Fe atoms and P atoms in step a is 1: 1.4, the remaining steps are the same as in Example 1.

[0047] The X-ray diffraction data of the obtained product is indistinguishable from that of Example 1 and Example 2. Compared with Example 1, the scanning electron microscope is obviously transformed from sheet-packed to columnar, and the electrochemical data shows that the initial discharge capacity of the product is better than that of Example 1 and Comparative Example 1. There is a noticeable attenuation.

[0048] The scanning electron microscope picture of this embodiment is shown in image 3 , is columnar, indicating that LiFePO prepared using the preparation method of the present invention 4 The sample can control the shape of the product under different conditions.

[0049] The discharge curve for the first time in this embodiment is shown in Figure 5 in c.

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Abstract

The invention relates to a preparation method of lithium battery material, in particular to a preparation method of LiFePO4 which mainly solves the technical problems existent in the prior art such as the crystal shape of lithium iron phosphate is particle-shape, a post heat treatment is needed during the preparation process, the preparation step is complicated and the preparation cost is high. The invention comprises the following steps: charging a phosphor-containing compound solution and a surfactant into a ferric salt solution for hydrothermal synthesis, wherein the ratio of Fe atom and P atom is 1:1-1.5, the mol ratio of the compound containing Fe atom and the surfactant is 1:1-3; discharging air by introducing inert gas; charging a lithium salt solution inwhich the mol ratio of Fe atom and Li atom is 1:2.5-3.5; heating the mixture solution for hydrothermal treatment by introducing inert gas; drying the product after pumping filtration and washing to obtain flake or cylindrical LiFePO4 crystal.

Description

technical field [0001] The invention relates to a preparation method of a lithium battery cathode material, in particular to a preparation method of LiFePO4. Background technique [0002] In 1997, Padhi and Goodenough found that olivine-type LiFePO4 has deintercalation behavior, its space group is Pnmb, oxygen atoms are arranged in a slightly dislocated hexagonal close-packed form, phosphorus atoms occupy the 4c ​​position of the tetrahedron, iron atoms and Li atoms occupy the 4c ​​and 4a positions of the octahedron, respectively. From the perspective of the b-axis direction, the FeO6 octahedra are connected at a certain angle on the bc plane, while the LiO6 octahedrons share edges along the b-axis direction to form a chain. One FeO6 octahedron shares edges with one PO4 tetrahedron and two LiO6 octahedrons respectively, and one PO4 tetrahedron also shares edges with two LiO6 octahedrons, which forms holes for free insertion and extraction of lithium ions. Therefore LiFePO ...

Claims

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Application Information

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IPC IPC(8): C01B25/45H01M4/58
CPCY02E60/10
Inventor 余爱水刘佳丽蒋蓉蓉龚金保王伯良王叶滔萧张兴
Owner 杭州金马新能源科技有限公司
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