Low-cost and high-rate graphene-based lithium iron phosphate electrode plate and preparation method thereof

An alkenyl lithium iron phosphate, high-rate technology, applied in the direction of battery electrodes, non-aqueous electrolyte battery electrodes, electrical components, etc., can solve the problem of slow electron conduction and lithium ion diffusion rate, limiting electrochemical performance of lithium iron phosphate batteries, particle Insufficient combination of substances and other issues, to achieve excellent cycle discharge rate performance, improve specific capacity and rate discharge performance, and reduce the effect of graphene agglomeration

Inactive Publication Date: 2019-04-30
湖北锂诺新能源科技有限公司
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

During the slurry preparation process, the active material and graphene are prone to agglomeration, the binder is not uniformly distributed, and the particle materials are not tightly combined, resulting in slow electron conduction and lithium ion diffusion rates during charge and discharge, resulting in severe electrode polarization.
The traditional slurry preparation uses a double planetary mixer for dispersion. The process takes a long time, the dispersion effect is poor, and the energy consumption is high. In addition, the graphene sheets are thick and easy to agglomerate, which limits the electrochemical performance of lithium iron phosphate batteries.

Method used

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  • Low-cost and high-rate graphene-based lithium iron phosphate electrode plate and preparation method thereof
  • Low-cost and high-rate graphene-based lithium iron phosphate electrode plate and preparation method thereof
  • Low-cost and high-rate graphene-based lithium iron phosphate electrode plate and preparation method thereof

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Experimental program
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Effect test

Embodiment 1

[0020] The preparation process of the graphene-based lithium iron phosphate pole piece is as follows: the positive electrode uses carbon-coated lithium iron phosphate as the active material, graphene as the conductive agent, PVDF as the binder, and the proportion of ingredients is LiFePO 4 :G:PVDF=94:3:3. LiFePO was first mixed with a ball mill 4 Dry mixing with PVDF powder, using zirconia ball milling beads for ball milling, the ball milling time is 3h, and the ball milling speed is 100rpm. Then the graphene conductive paste was added to the solvent for ultrasonic stirring, the amount of NMP added was the same as the quality of the graphene conductive paste, and the ultrasonic stirring time was 1 h. The pre-dry mixed powder was added to the graphene NMP solvent, and a double planetary mixer was used for high-speed dispersion, the stirring power was 1000W, and the stirring time was 2h. The prepared positive electrode slurry was coated on both sides of the carbon-coated alumi...

Embodiment 2

[0022] The preparation process of the graphene-based lithium iron phosphate pole piece is as follows: the positive pole piece uses carbon-coated lithium iron phosphate as the active material, graphene as the conductive agent, PVDF as the binder, and the proportion of ingredients is LiFePO 4 :G:PVDF=94:3:3. LiFePO was first mixed with a ball mill 4 Dry mixing with PVDF powder, using zirconia ball milling beads for ball milling, the ball milling time is 3h, and the ball milling speed is 100rpm. Then the graphene conductive paste was added to the solvent for ultrasonic stirring, the amount of NMP added was the same as the quality of the graphene conductive paste, and the ultrasonic stirring time was 1 h. The pre-dry mixed powder was added to the graphene NMP solvent, and high-speed dispersion was carried out by wet grinding, and the grinding and dispersing time was 2h. The prepared positive electrode slurry is coated on both sides and carbon-coated aluminum foil current collect...

Embodiment 3

[0024] The preparation process of the graphene-based lithium iron phosphate pole piece is as follows: the positive pole piece uses carbon-coated lithium iron phosphate as the active material, graphene as the conductive agent, PVDF as the binder, and the proportion of ingredients is LiFePO 4 :G:PVDF=94:3:3. LiFePO was first mixed with a ball mill 4 Dry mixing with PVDF powder, using zirconia ball milling beads for ball milling, the ball milling time is 3h, and the ball milling speed is 100rpm. Then the graphene conductive paste was added to the solvent for ultrasonic stirring, the amount of NMP added was the same as the quality of the graphene conductive paste, and the ultrasonic stirring time was 1 h. The pre-dry mixed powder was added to the graphene NMP solvent, and a high-speed homogenizer was used for high-speed dispersion. The valve pressure of the homogenizer was 400bar, the nozzle pressure was 500bar, and the dispersion time was 2h. The prepared positive electrode slu...

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Abstract

The invention relates to a graphene-based lithium iron phosphate positive electrode plate and a preparation method thereof. The positive electrode plate uses carbon-coated lithium iron phosphate as apositive electrode active material, thin graphene as a conductive agent and polyvinylidene fluoride as a binder, with the composition ratio of lithium iron phosphate (LiFePO4): graphene: polyvinylidene fluoride being (92-96): (2-4): (2-4). The preparation method includes the following steps: lithium iron phosphate and polyvinylidene fluoride powder are milled for 1-3h and dry-mixed; graphene conductive slurry is added to N-methyl-pyrrolidone organic solvent and ultrasonic stirring is carried out for 0.5-1h; and the dry-mixed powder is added to the graphene N-methyl-pyrrolidone solvent, the slurry is first dispersed at high speed by a wet grinding machine for 2-4h and then dispersed in a high-pressure homogenizer for 1-2h to obtain positive electrode slurry. By adopting the slurry preparedin the invention, the dispersion degree of the slurry can be significantly improved. A graphene-based lithium iron phosphate battery prepared in the invention has excellent cyclic discharge rate performance. The specific discharge capacity at 20C is 105-115mAh / g, and the capacity retention rate is 75-85%.

Description

technical field [0001] The invention relates to a preparation method of a lithium iron phosphate pole piece, in particular to a graphene-based lithium iron phosphate pole piece with low cost and high magnification and a preparation method. Background technique [0002] In 1997, Goodenough et al. of Texas State University found that lithium iron phosphate can be used as a positive electrode active material for lithium ions. At present, lithium iron phosphate has been widely used in electric vehicles, energy storage power stations, electronic communications and other fields due to its excellent performance. [0003] However, lithium iron phosphate also has some shortcomings, such as low electronic conductivity, low lithium ion diffusion coefficient, poor rate discharge and low temperature performance. In order to improve and improve the electrochemical performance of lithium iron phosphate battery, it can be modified by surface carbon coating, bulk doping, nano-particles and ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/58H01M4/587H01M4/62H01M4/13H01M4/139H01M10/0525B02C17/10B02C21/00
CPCB02C17/10B02C21/00H01M4/13H01M4/139H01M4/366H01M4/5825H01M4/587H01M4/625H01M10/0525Y02E60/10
Inventor 马卫孙伟兵张天赐华诚王聪
Owner 湖北锂诺新能源科技有限公司
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