Modification method for improving high-temperature cycle performance and ionic conductance of lithium iron phosphate material

A lithium iron phosphate, high-temperature cycle technology, applied in the direction of circuits, electrical components, battery electrodes, etc., can solve the problems of difficult diffusion rate of lithium ions and insufficient research on diffusion mechanism, and achieve low heat treatment temperature, stable and controllable product performance, The effect of stable performance

Inactive Publication Date: 2011-09-14
SHENZHEN GRADUATE SCHOOL TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Because the current research on the diffusion mechanism of lithium ions in lithium iron phosphate is not deep enough, it is difficult to improve the diffusion rate of lithium ions from the internal structure.

Method used

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  • Modification method for improving high-temperature cycle performance and ionic conductance of lithium iron phosphate material
  • Modification method for improving high-temperature cycle performance and ionic conductance of lithium iron phosphate material
  • Modification method for improving high-temperature cycle performance and ionic conductance of lithium iron phosphate material

Examples

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Effect test

Embodiment 1

[0018] Example 1: Take an appropriate amount of tetraethyl orthosilicate and absolute ethanol to prepare a 2M solution, then add an appropriate amount of citric acid and polyvinyl alcohol as a chelating agent, and stir continuously at about 50°C to form a sol with a suitable viscosity. Silica accounts for 2wt% of the lithium iron phosphate by adding the lithium iron phosphate powder, continue to add absolute ethanol, and continue to stir, stop adding absolute alcohol after the sample viscosity is moderate, and continue to stir for 2 hours. After stirring evenly, place in a drying oven at 70° C. for heat preservation and drying to obtain the precursor. The precursor was heated up to 500°C at a speed of 5°C / min and kept for 1 hour, cooled to room temperature with the furnace, then crushed and passed through a 200-mesh sieve to obtain the final product. The transmission electron microscope photograph of the obtained product is as follows: figure 1 ,Depend on figure 1 It can be ...

Embodiment 2

[0019] Example 2: Take an appropriate amount of aluminum isopropoxide and absolute ethanol to prepare a 2M solution, then add an appropriate amount of citric acid and polyvinyl alcohol as a chelating agent, and stir continuously at about 50°C to form a sol with a suitable viscosity. Aluminum accounted for 2wt% of the lithium iron phosphate and added to the lithium iron phosphate powder, continued to add absolute ethanol, and continued to stir, stop adding absolute alcohol after the sample viscosity was moderate, and continued to stir for 2 hours. After stirring evenly, place in a drying oven at 70° C. for heat preservation and drying to obtain the precursor. The precursor was heated up to 500°C at a speed of 5°C / min and kept for 1 hour, cooled to room temperature with the furnace, then crushed and passed through a 200-mesh sieve to obtain the final product. The transmission electron microscope photograph of the obtained product is as follows: figure 2 ,Depend on figure 2 I...

Embodiment 3

[0022] Example 3: Take an appropriate amount of butyl titanate and absolute ethanol to prepare a 2M solution, then add an appropriate amount of citric acid and polyvinyl alcohol as a chelating agent, and stir continuously at about 50°C to form a sol with a suitable viscosity. Titanium accounted for 2wt% of the lithium iron phosphate was added to the lithium iron phosphate powder, continued to add absolute ethanol, and continued to stir, stop adding absolute alcohol after the sample viscosity was moderate, and continued to stir for 2 hours. After stirring evenly, place in a drying oven at 70° C. for heat preservation and drying to obtain the precursor. The precursor was heated up to 500°C at a speed of 5°C / min and kept for 1 hour, cooled to room temperature with the furnace, then crushed and passed through a 200-mesh sieve to obtain the final product. The transmission electron micrograph of the resulting product shows that the surface of the coated lithium iron phosphate partic...

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Abstract

The invention discloses a modification method for improving the high-temperature cycle performance and ionic conductance of a lithium iron phosphate material. The method mainly comprises the following steps of: mixing an organic compound which contains silicon, aluminum and titanium with lithium iron phosphate; performing certain heat treatment; and coating silicon dioxide, aluminum oxide or titanium oxide onto the surface of the lithium iron phosphate material to fulfill the aim of improving the electrochemical performance of the lithium iron phosphate material. The high-temperature cycle performance and the high-magnification charging-discharging current cycle capacity of coating-modified lithium iron phosphate are enhanced, and the impedance of a prepared electrode is remarkably reduced. The lithium iron phosphate material can be applied to more fields. A coating method has the advantages of simple process, low cost, stable and controllable product performance and suitability for industrial production.

Description

technical field [0001] The invention belongs to the field of chemical batteries, and mainly relates to a coating modification method for improving the high-temperature cycle performance and ion conductance of lithium iron phosphate materials. Background technique [0002] In recent years, lithium-ion batteries have continuously expanded their application fields due to their lightness, high efficiency, long cycle life, and good safety performance, and have gradually been applied to the field of electric vehicles. However, what restricts its development is that the performance of the cathode material has not been satisfied. Lithium iron phosphate (LiFePO 4 ) has the characteristics of high quality, low price, green and environmental protection, meets the requirements of the application field of electric vehicles, and has a huge market prospect. [0003] Lithium iron phosphate belongs to olivine structure, its theoretical capacity is 170mAh / g, and its voltage platform is about...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/1397
CPCY02E60/122Y02E60/10
Inventor 赵世玺李颖达南策文陈卫强
Owner SHENZHEN GRADUATE SCHOOL TSINGHUA UNIV
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