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Method for improving lithium ion battery anode material LiFePO4/C tap density

A technology for lithium-ion batteries and cathode materials, applied in the field of preparation of cathode materials for lithium-ion batteries, can solve the problems of demanding raw materials, low tap density, complicated process, etc., and achieve strong adhesion, moderate tap density, and simple process Effect

Inactive Publication Date: 2009-12-16
WUHAN UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the problem of low tap density still exists
There are also many ways to solve it, such as increasing the tap density of the raw material, changing the roasting process, etc., but these methods are either demanding on the raw material, or the process is complicated, and it is not easy to implement

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] Weigh 8 mol of FePO 4 2H 2 O and LiOH·H 2 O, take LiOH·H 2 O, FePO 2H 2 The molar ratio of O is 1:1, and the amount of solid PEG (molecular weight 20000) added is 200g / molFePO 4 2H 2 O. LiOH·H 2 O, FePO 4 2H 2 After O and PEG are evenly mixed, add 1% additive B in the finished product 2 o 3 , add 100ml / molFePO 4 2H 2 The deionized water of O was adjusted to rheological state, and they were roasted at 300, 600, and 800°C under the protection of argon for 6h. The resulting product was characterized by XRD, and its XRD spectrum was consistent with that of standard LiFePO 4 The spectrum matches (PDF832092), B 2 o 3 to LiFePO 4 The crystal structure has no effect. Compared with the samples without additives, the tap density of the obtained products is improved, and the effect of the 600°C sample is the most obvious. The tap density is 0.95g / mL. Compared with the sample without additives (the tap density is 0.74g / mL), the tap density is greatly improved. G...

Embodiment 2

[0027] Weigh 24mol of FePO 4 2H 2 O and LiOH·H 2 O, take LiOH·H 2 O, FePO 4 2H 2 The molar ratio of O is 1:1, and the amount of solid PEG (molecular weight 4000) added is 150g / molFePO 4 2H 2 O. LiOH·H 2 O, FePO 4 2H 2 After O and PEG are mixed evenly, add 1% additive LiF of finished product, add 100ml / molFePO 4 2H 2 Adjust the deionized water of O to a rheological state, and roast at 600 ° C for 1, 6, and 20 h under the protection of argon. The resulting product was characterized by XRD, and its XRD spectrum was consistent with that of standard LiFePO 4 The spectra match (PDF832092), LiF vs LiFePO 4 The crystal structure has no effect. The tap density of the obtained product is improved compared with the samples without additives. Taking the sample calcined for 6 hours under the protection of argon as an example, the tap density of the obtained product is 1.0 g / mL, which is greatly improved compared with the sample without additives (tap density is 0.77 g / mL). ...

Embodiment 3

[0030] Replace the above raw materials with Li 2 CO 3 、FePO 4 4H 2 O, PEG (liquid, molecular weight 300), add the additive TiO of 1% of the finished product 2 . The precursor was prepared in the same steps as above, and then the obtained precursor was calcined at 700° C. in a nitrogen atmosphere for 6 hours to obtain the target product. the above Li 2 CO 3 Change to CH 3 COOLi·2H 2 O, repeat above steps, also obtain target product,

[0031] The resulting two target products were tested by XRD, and the results were compared with undoped LiFePO 4 In contrast, it can be seen that the obtained target product has the crystal form of LiFePO at the same time, and no new impurity phase is formed. The tap density is higher than that of undoped. The electrochemical performance is good. It shows that changing raw materials and protective atmosphere can also achieve the expected effect.

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Abstract

The invention relates to a method for advancing the tap density of the lithium ion cell anode material LiFePO4 / C, wherein FePO4-xH2O(x=2 or 4), LiOH-H2O(or Li2CO3, CH3COOLi-2H2O) and polyethylene glycol are used as the raw materials, added with the additive titanium dioxide(or lithium fluoride, vanadium pentexide, boric anhydride), added with water to furnish into the fluid abnormality after being mixed evenly, then baked into LiFePO4 / C anode material under the protection of the inert gas. The invention is characterized in that, the tap density of the lithium ion cell anode material LiFePO4 / C is markedly increased after adding the additive with certain amount. The lithium ion cell prepared by the material is provided with good specific capacity of the first charge and discharge, the good charge-discharge efficiency, the good cycle efficiency and the high multiplying power performance, which is suitable for the lithium ion cell.

Description

technical field [0001] The invention relates to a method for preparing lithium-ion battery positive electrode materials, especially suitable for improving the lithium-ion battery positive electrode material LiFePO prepared by rheological phase reaction method. 4 / C tap density method. Background technique [0002] LiFePO 4 As a lithium-ion battery cathode material has great advantages, but it also has some fatal disadvantages, that is, LiFePO 4 The electronic conductivity and ion diffusion rate are extremely low, which leads to rapid capacity decay during high-current charge and discharge, and poor high-rate performance. Therefore, it is LiFePO to improve its conductivity. 4 main research directions. Second LiFePO 4 The density itself is small, and the bulk density is even smaller, resulting in a small tap density of the material, resulting in a low energy density of the battery, which affects the practical application of the material, so increasing the LiFePO 4 The tap...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/58H01M4/48H01M4/04B01J19/00
CPCY02E60/10
Inventor 张克立王丽娜孔立群刘寒露缪兆盛尹盛玉王小艳张梅芳孙洪勇
Owner WUHAN UNIV
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