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In-situ carbon coating method for lithium iron phosphate

A technology of lithium iron phosphate and carbon coating, which is applied in the direction of structural parts, electrical components, battery electrodes, etc., can solve the problems of poor conductivity and uneven carbon coating, achieve uniform carbon coating, simple process, and benefit The effect of commercialization

Inactive Publication Date: 2013-12-04
SHANGHAI BAOSTEEL MAGNETICS +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to provide a method for carbon-coating lithium iron phosphate particles, aiming to solve the shortcomings of lithium iron phosphate materials such as uneven carbon coating and poor conductivity.

Method used

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  • In-situ carbon coating method for lithium iron phosphate
  • In-situ carbon coating method for lithium iron phosphate
  • In-situ carbon coating method for lithium iron phosphate

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] Dissolve 20g of polyvinyl alcohol (PVA) in 80mL of deionized water to form a solution with a PVA content of 20wt%;

[0026] Pour 72g of hydrothermally synthesized lithium iron phosphate powder into the above PVA solution, and form a suspension after fully stirring. The mass ratio between the carbon brought in by the organic carbon source material and lithium iron phosphate is 15%;

[0027] Pour the above solution into 200mL acetone solvent, stir and let stand for 1h;

[0028] The above solution was filtered, and the obtained powder was vacuum-dried at 100°C; its SEM photo is as follows figure 1 shown.

[0029] The above powder was kept at 600°C for 5 hours under a nitrogen atmosphere to obtain a uniform carbon-coated lithium iron phosphate material. The SEM photo is as follows: figure 2 shown.

[0030] The cycle curves (0.2C) of the carbon-coated lithium iron phosphate material prepared in this example and the non-carbon-coated lithium iron phosphate are as follows ...

Embodiment 2

[0032] 1 gram of PVA was dissolved in 99mL of deionized water to form a solution with a PVA content of 1wt%;

[0033] Pour 18 grams of hydrothermally synthesized lithium iron phosphate powder and 0.9 grams of conductive carbon black into the PVA solution, and form a suspension after fully stirring. The mass ratio between the carbon brought by PVA and lithium iron phosphate is 3%. The mass ratio between the carbon carried by the conductive carbon black and lithium iron phosphate is 5%;

[0034] Pour the above solution into 200mL acetone solvent, stir and let stand for 1h;

[0035] The above solution was filtered, and the obtained powder was vacuum-dried at 100°C;

[0036] The above powder was heat-treated at 800°C for 5 hours under a nitrogen atmosphere to obtain a uniform carbon-coated lithium iron phosphate material;

Embodiment 3

[0038] Dissolve 10 grams of polyvinyl butyral (PVB) in 114 mL (90 g) of methanol to form a solution with a PVB content of 10 wt %;

[0039] Pour 135 grams of hydrothermally synthesized lithium iron phosphate powder into the above PVB solution, and form a suspension after fully stirring. The mass ratio between the carbon brought by PVB and lithium iron phosphate is 5%;

[0040] Pour the above solution into 200mL water, stir and let stand for 1h;

[0041] The above solution was filtered, and the obtained powder was vacuum-dried at 100°C;

[0042] The above powder is heat-treated at 600°C and 5°C under a nitrogen atmosphere to obtain a uniform carbon-coated lithium iron phosphate material.

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Abstract

The invention discloses an in-situ carbon coating method for lithium iron phosphate. The method comprises the steps: dissolving an organic carbon source in a solvent A to form an organic carbon source solution, then adding lithium iron phosphate particles into the above organic carbon source solution, stirring uniformly to form a carbon source material suspending liquid; dumping the above carbon source material suspending liquid into a solvent B in which the above carbon source material has extremely low solubility, to make the carbon source material uniformly precipitate on the surface of the lithium iron phosphate particles, filtering and drying to obtain carbon source material coated lithium iron phosphate particles; placing the carbon source material coated lithium iron phosphate particles in nitrogen or inert gas for protection, keeping temperature at 350 DEG C -850 DEG C for 1-10 h to fully carbonize the carbon source material and further to obtain the carbon uniformly-coated lithium iron phosphate material. The method of the invention helps the carbon source to insitu precipitate on the surface of the lithium iron phosphate particles, and the carbon coating is uniform; the carbon coating technology needs no complex and expensive ball mill mixing devices; and the method has a simple technological process and is beneficial to commercialization.

Description

technical field [0001] The invention relates to the technical field of cathode materials for lithium ion secondary batteries, in particular to a method for uniform carbon coating of lithium iron phosphate particles. Background technique [0002] In the context of the global energy and environmental crisis, lithium-ion secondary batteries for electric vehicles are becoming a hot and urgent topic. LiFePO 4 As a new type of lithium-ion battery cathode material, it has the advantages of stable voltage, good cycle performance, good safety, environmental friendliness, and low cost, and has broad application prospects in the field of power batteries. However, due to the inherent limitations of its structure, LiFePO 4 The poor electrical conductivity severely limits its electrochemical performance and affects its commercial application. Therefore, how to improve LiFePO 4 The electrical conductivity has become a research hotspot. Armand et al. found that the LiFePO 4 The surfac...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/1397H01M4/62
CPCY02E60/122Y02E60/10
Inventor 陈元峻张五星徐辉宇冯炜黄云辉彭蕴龙李斌
Owner SHANGHAI BAOSTEEL MAGNETICS
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