Lithium iron phosphate secondary structure, preparation method of the lithium iron phosphate secondary structure, and lithium ion battery

一种磷酸铁锂、二次结构的技术，应用在二次电池、电池电极、结构零件等方向，能够解决增加工艺步骤和条件、锂离子扩散速度慢、多导电剂和粘结剂等问题，达到提高堆积密度、易于制浆和成膜、缩短扩散路径的效果

Active Publication Date: 2013-06-05
TSINGHUA UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the disadvantage of lithium iron phosphate is its poor conductivity and slow diffusion of lithium ions.
[0003] However, nano-scale lithium iron phosphate has its own shortcomings and problems when it is used directly. For example, the packing density of nano-scale lithium iron phosphate is low, and more conductive agents and binders need to be used when making electrode sheets, so that The capacity-to-volume ratio of batteries is limited
In addition, due to the large surface area of ​​nano-scale lithium iron phosphate particles, there are also difficulties in the preparation of electrode slurry and electrode sheet coating, and it is not easy to form a relatively uniform electrode sheet.
[0004] Although in the prior art, the nano-scale lithium iron phosphate particles are also used as primary particles, spray drying and other secondary molding methods are used to prepare secondary spherical particles composed of a large number of lithium iron phosphate primary particles, but this method is relatively complicated. A series of process steps and conditions are added, which greatly increases the production cost

Method used

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  • Lithium iron phosphate secondary structure, preparation method of the lithium iron phosphate secondary structure, and lithium ion battery
  • Lithium iron phosphate secondary structure, preparation method of the lithium iron phosphate secondary structure, and lithium ion battery
  • Lithium iron phosphate secondary structure, preparation method of the lithium iron phosphate secondary structure, and lithium ion battery

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preparation example Construction

[0026] see figure 1 , the embodiment of the present invention provides a method for preparing a secondary structure of lithium iron phosphate, which includes the following steps:

[0027] Step 1, providing lithium source solution, ferrous source solution and phosphorus source solution respectively, the lithium source solution, ferrous source solution and phosphorus source solution are lithium source compound, ferrous source compound and phosphorus source compound dissolved in an organic solvent respectively Obtained, and the concentration of lithium ions in the lithium source solution is greater than or equal to 1.8mol / L;

[0028] Step 2, mixing the lithium source solution, the ferrous source solution and the phosphorus source solution to form a mixed solution; and

[0029] In step 3, the mixed solution is heated in a solvothermal reaction kettle for reaction, and the reaction product is a secondary structure of lithium iron phosphate.

[0030] In step 1, the lithium source ...

Embodiment 1

[0054] In this embodiment, the lithium source compound is lithium hydroxide (LiOH·H 2 O), the ferrous source compound is ferrous sulfate (FeSO 4 ·7H 2 O), the phosphorus source compound is phosphoric acid (H 3 PO 4 ), the organic solvent is ethylene glycol. First, 1.6184g LiOH·H 2 O was dissolved in 18.9 mL of ethylene glycol to give Li + Lithium hydroxide solution with a concentration of 2mol / L, at this time LiOH reaches saturation in ethylene glycol. Second, the 3.8922gFeSO 4 ·7H 2 O was dissolved in 23.3 mL of ethylene glycol to give Fe 2+ Ferrous sulfate solution with a concentration of 0.6mol / L. Again, add 944 μL H 3 PO 4 Add it into the ferrous sulfate solution, stir to obtain a mixed solution, then add the lithium hydroxide solution into the above mixed solution, and continue to stir for 30 min. In the finally obtained mixed solution, the molar ratio among the lithium hydroxide, ferrous sulfate and phosphoric acid is 2.7:1:1. Finally, put the mixed solution...

Embodiment 2

[0061] In this embodiment, the lithium source compound is lithium hydroxide (LiOH·H 2 O), the ferrous source compound is ferrous sulfate (FeSO 4 ·7H 2 O), the phosphorus source compound is phosphoric acid (H 3 PO 4 ), the organic solvent is a mixed solvent of ethylene glycol and glycerol volume ratio of 2:1. First, 1.6184g LiOH·H 2 O was dissolved in 18.9 mL of mixed solvent to obtain Li + Lithium hydroxide solution with a concentration of 2 mol / L. Second, the 3.8922gFeSO 4 ·7H 2 O was dissolved in 23.3 mL of mixed solvent to obtain Fe 2+ Ferrous sulfate solution with a concentration of 0.6mol / L. Again, add 944 μL H 3 PO 4 Add it into the ferrous sulfate solution, stir to obtain a mixed solution, then add the lithium hydroxide solution into the above mixed solution, and continue to stir for 30 min. In the finally obtained mixed solution, the molar ratio among the lithium hydroxide, ferrous sulfate and phosphoric acid is 2.7:1:1.5. Put the mixed solution into a sol...

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Abstract

The invention relates to a preparation method of a lithium iron phosphate secondary structure. The preparation method comprises the following steps of 1, preparing a lithium source solution, a ferrous source solution and a phosphorus source solution by respectively dissolving a lithium source compound, a ferrous source compound and a phosphorus source compound in organic solvents, wherein the lithium source solution has the lithium ion concentration more than or equal to 1.8mol / L, 2, mixing the phosphorus source solution and the ferrous source solution into a first solution, and adding the lithium source compound into the first solution to obtain a second solution, and 3, heating the second solution in a solvothermal reactor for a reaction. The invention also relates to the lithium iron phosphate secondary structure and a lithium ion battery.

Description

technical field [0001] The invention relates to a lithium iron phosphate and a preparation method thereof, and a lithium ion battery, in particular to a lithium iron phosphate with a secondary structure, a preparation method thereof, and a lithium ion battery. Background technique [0002] Olivine-type lithium iron phosphate, as a kind of positive electrode active material with good safety, low price and environmental friendliness, has been paid great attention to by people. However, the disadvantage of lithium iron phosphate is its poor conductivity and slow diffusion of lithium ions. The existing methods for improving the conductivity of lithium iron phosphate mainly include coating lithium iron phosphate with carbon materials and doping lithium iron phosphate with metal ions. In terms of improving the diffusion rate of lithium ions, people try to nanoscale lithium iron phosphate to shorten the diffusion channel of lithium ions. Existing methods for preparing nanoscale l...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/58H01M4/136H01M10/0525
CPCY02E60/12H01M4/5825H01M4/58Y02E60/122H01M4/136H01M10/0525C01B25/45Y02E60/10Y02P70/50
Inventor 王莉何向明孙文婷李建军黄贤坤高剑
Owner TSINGHUA UNIV
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