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Preparation method of modified graphite cathode material for lithium ion batteries

A technology for lithium-ion batteries and graphite negative electrodes, applied in battery electrodes, negative electrodes, secondary batteries, etc. The problems of mutual adhesion of graphite-coated particles can avoid the formation of unstable SEI film, improve cycle performance and rate performance, and achieve excellent cycle and rate performance.

Inactive Publication Date: 2016-07-27
田东
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Chinese patents CN101604743A and CN1224251A etc. adopt resins as coating materials, the main advantage is that the resin has good fluidity at low temperature, not only can coat the surface, but also easily penetrate into the inside of graphite particles through the micropores in graphite, which is beneficial to the improvement of graphite particles. The tap density and electronic conductivity are beneficial, and it can also be cured by heating, introducing catalysts or ultraviolet radiation. During the pyrolysis process of the resin, it will not melt and deform, and will not produce obvious expansion, but there are also some problems, mainly: The affinity between resin materials and graphite is poor, so the carbon materials obtained by pyrolysis and graphite are not firmly bonded, and the carbon materials obtained by resin pyrolysis are low in yield and brittle. The surface area is relatively high, and the cohesive force of the resin is strong, which is easy to cause the coated particles to stick together, and the coating layer is easily damaged when crushed after heat treatment
The above problems affect the cycle efficiency, cycle stability and compressibility of graphite electrodes of resin-coated graphite materials.
[0005] Chinese patents CN96198348.5 and CN03120199.6, etc. use pitch, petroleum tar, coal tar or their mixtures to coat graphite. The specific surface area of ​​pitch pyrolytic carbon is smaller than that of resin pyrolytic carbon coated graphite, and the affinity with graphite Good, the structure is stronger, but the asphalt coating will be deformed due to melting during the heating process, too much dosage will easily cause the coated graphite particles to stick to each other, too little dosage will easily cause coating unevenness, and it will easily expand during the heating process , affecting the electrical properties of graphite

Method used

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  • Preparation method of modified graphite cathode material for lithium ion batteries
  • Preparation method of modified graphite cathode material for lithium ion batteries

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Embodiment 1

[0028] A preparation method of modified graphite negative electrode material for lithium ion battery, the preparation steps are as follows:

[0029] (1) Weigh 2g of nickel chloride to prepare an aqueous solution of nickel chloride with a solubility of 0.5mol / L. According to the ratio of m(graphite):m(Ni)=100:5, add 18.1g of graphite powder and keep stirring to obtain a mixed solution;

[0030] (2) Slowly add 0.5mol / L ammonia solution to the above mixed solution, a total of 61.7ml, to form a precipitate and obtain Ni(OH) 2 A mixed solution attached to the surface of graphite powder;

[0031] (3) Centrifuge and dry the mixed solution containing precipitate obtained in step 2 to obtain graphite / Ni(OH) 2 solid powder;

[0032] (4) Weigh 1.5g of phenolic resin and dissolve it in absolute ethanol, add the solid powder in step 3, stir for 1-2 hours, and then stir continuously at 50-70°C until evaporated to dryness to obtain a solid powder;

[0033] (5) Heat the above solid powder...

Embodiment 2

[0038] A preparation method of modified graphite negative electrode material for lithium ion battery, the preparation steps are as follows:

[0039] (1) Weigh NiSO 4 ·6H 2 O compound 10g, prepare a nickel chloride aqueous solution with a solubility of 0.5mol / L, add 22.32g of graphite powder according to the ratio of m(graphite):m(Ni)=100:10, and keep stirring to obtain a mixed solution;

[0040] (2) Slowly add 1mol / L sodium hydroxide solution to the above mixed solution, a total of 78ml, to form a precipitate and obtain Ni(OH) 2 A mixed solution attached to the surface of graphite powder;

[0041] (3) Centrifuge and dry the mixed solution containing precipitate obtained in step 2 to obtain graphite / Ni(OH) 2 solid powder;

[0042] (4) Weigh 1.3g of epoxy resin and dissolve it in absolute ethanol, add the solid powder in step 3, stir for 1-2 hours, and then stir continuously at 50-70°C until evaporated to dryness to obtain a solid powder;

[0043] (5) Heat the above solid p...

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Abstract

The invention discloses a preparation method of a modified graphite cathode material for lithium ion batteries. Graphite powder serving as a core and metal nickel serving as a shell layer form an inner core-shell structure of the cathode material for the lithium ion batteries, and the outer surface of the core-shell structure is coated with a carbon layer. A carbothermal reduction method is adopted by making use of carbon formed in an organic resin pyrolysis process, addition of the metal nickel effectively improves rate performance and realizes isolation of the graphite powder and the electrolyte to prevent direct contact of the graphite powder and the electrolyte, and accordingly graphite peeling and efflorescence caused by co-intercalation of lithium ions and the electrolyte are prevented, and cycle performance and rate performance of graphite serving as the cathode material for the lithium ion batteries in a charge-discharge process are greatly improved. In addition, the surface carbon layer plays a role in enhancement of electrical conductivity of the composite material.

Description

technical field [0001] The invention belongs to the technical field of negative electrode materials of lithium ion batteries, and in particular relates to a preparation method of modified graphite negative electrode materials of lithium ion batteries. Background technique [0002] Lithium-ion batteries have been widely used in portable electronic devices such as notebook computers, mobile phones, and medical microelectronics due to their high energy density and excellent cycle performance. However, there are still many problems to be solved if it is to be applied to broader fields such as large stationary energy storage devices and electric vehicles. These issues include how to further increase the energy density of lithium-ion batteries, enhance the matching between battery packs, reduce the capacity attenuation during cycling, improve safety during work, broaden the normal operating temperature range, enhance the reliability of materials, reduce the production costs, etc....

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/587H01M4/62H01M10/0525
CPCH01M4/366H01M4/587H01M4/62H01M4/628H01M10/0525H01M2004/027H01M4/36Y02E60/10
Inventor 田东
Owner 田东