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Method for improving electrical property of natural graphite

A technology of natural graphite and electrical properties, applied in the direction of graphite, circuits, electrical components, etc., can solve the problems of coating particles sticking together, difficult to master the technology, and weak combination of carbon materials and graphite, so as to improve uniformity, The effect of improving the overall electrical performance

Inactive Publication Date: 2013-02-06
IRICO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] By crushing, grading and processing graphite particles into spherical shapes, the tap density and rate characteristics of graphite are significantly improved, but the first charge and discharge efficiency and cycle stability are poor
In order to solve the above problems, researchers have adopted various methods to carry out surface treatment on graphite, such as US Patent No.6432583B 1 Using the method of chemical vapor deposition, the organic gas is thermally decomposed in the fluidized bed formed in the inert carrier gas, and a layer of carbon material is deposited on the graphite surface. This method has relatively high requirements for equipment and is difficult to master.
US Patent, No.3,011,920 discloses the use of lithium salt or alkali to passivate the graphite surface to form a passivation film on the graphite surface. The method is simple to operate and easy to industrialized large-scale production. The wetness or hydrophilicity of the surface, if not handled properly, will increase the irreversible capacity loss of the first charge and discharge, and it is difficult to achieve the desired effect
[0006] Coating graphite materials with resin polymer pyrolytic carbon, such as CN1304187, etc., can also significantly improve the electrical properties of graphite. The main advantage is that the resin has good fluidity at low temperature, not only can coat the graphite surface, but also easily The micropores in graphite penetrate into the interior of graphite particles, which is beneficial to improve the tap density and electronic conductivity of graphite particles, but there are also some problems, such as the poor affinity between resin materials and graphite, and the pyrolysis of graphite particles The combination of carbon materials and graphite is not firm; the yield of carbon materials obtained by pyrolysis of resin is low and brittle; during the process of pyrolysis of resin, there are many volatiles and the specific surface area is high; the adhesiveness of resin is strong, which is easy to cause coating The particles are bonded together, and it is easy to cause damage to the coating layer when crushed after heat treatment
The above problems affect the cycle efficiency, cycle stability and compressibility of graphite electrodes of resin-coated graphite materials.

Method used

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  • Method for improving electrical property of natural graphite
  • Method for improving electrical property of natural graphite
  • Method for improving electrical property of natural graphite

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preparation example Construction

[0029] A preparation method for improving the electrical properties of natural graphite proposed by the present invention includes the following steps: (1) coating a mixed coating composed of two or more polymers on the surface of graphite particles, the mixed coated polymer One is asphalt, and the rest are condensation polymers or organic mixed coatings containing condensation polymers; (2) drying or curing the organic polymer layer coated on the graphite surface below 400°C; (3) crushing and grading , to remove particles with a particle size of less than 5 μm; (4) heat treatment at 400-800°C for 5-20 hours under the protection of an inert atmosphere and then cool to below 60°C; (5) oxidation resistance at a temperature not higher than 420°C Treat in the atmosphere for 3 minutes to 25 hours; (6) Heat treatment at 800-1350°C for 1-15 hours under the protection of an inert atmosphere and then cool to below 60°C; (7) Crush and classify to ensure that the D50 is between 10-20um b...

Embodiment 1

[0039] In a 4L container, add 0.4L toluene, add 6.8g natural asphalt and 12.6g phenolic resin (containing 50% each of methanol solvent and phenolic resin solid content) at a rate of 1g / min successively under stirring at 15 rev / s, until the asphalt After dissolving completely, keep original rotating speed constant, add 0.26kg natural graphite under stirring, be warming up to 110 ℃ in 1.5 hours, then keep stirring for 4 hours, evaporate solvent, obtain the organic polymer that is coated on the graphite particle surface.

[0040] Under the protection of nitrogen, put the natural graphite mixed and coated with pitch and phenolic resin into the carbonization furnace and raise the temperature to 720°C at a rate of 1°C / min, and maintain it for 2.5 hours, then cool naturally to 60°C and take it out. After crushing, sieving and grading to obtain particles with a D50 particle size of 10 μm, heat it up to 1150°C at 1.2°C / min under nitrogen protection, then keep it warm for 3 hours, turn o...

Embodiment 2

[0042] In a 4L container, add 0.4L xylene, and add 43.6g novolac resin (containing 50% methanol solvent and 50% novolac resin solids) successively at a rate of 1g / min under stirring at 15 rpm, until the resin is completely dissolved Finally, keep the original rotating speed constant, and add 0.26kg of natural graphite under stirring. All the other steps are the same as in Example 1.

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Abstract

The invention relates to lithium ion battery cathode material natural graphite, in particular to a method for improving electrical property of natural graphite. The method is characterized by comprising the steps of firstly, adding solvent into a reactor, stirring, sequentially adding asphalt, polycondensate or organic mixture containing polycondensate, stirring, adding natural graphite, and evaporating solvent; secondly, drying and solidifying organic polymer coated on the surface of the graphite for 8-16 hours; thirdly, crushing obtained graphite particles; fourthly, performing hot treatment at 400-800 DEG C for 5-20 hours; fifthly, processing at 100-420 DEG C for 3 minutes to 25 hours; performing hot treatment at 800-1350 DEG C for 1-15 hours; and seventhly, crushing the graphite particles again until D50 particle size of the graphite particles ranges from 10 micrometers to 20 micrometers. By the method, uniformity and operability of polymer-coated graphite particles are improved, and comprehensive electrical property of the polymer-coated graphite particles is also improved.

Description

technical field [0001] The invention relates to natural graphite, a negative electrode material of a lithium ion battery, in particular to a method for improving the electrical performance of natural graphite. Background technique [0002] Lithium-ion batteries have developed rapidly since they were invented by Sony Corporation of Japan in the early 1990s. At present, the application scope has expanded from mobile communication power supplies, digital cameras, notebook computers, etc. to large energy storage batteries, power tools, electric vehicles, etc. In the field, the development trend of high specific characteristics, low price and environmental protection of batteries is obvious, which benefit from the improvement and innovation of electrode materials. For lithium-ion battery anode materials, artificial graphite and natural graphite have the characteristics of low lithium intercalation / deintercalation potential, high reversible capacity, abundant resources, and low pr...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B31/04H01M4/587C01B32/21
CPCY02E60/12Y02E60/10
Inventor 高洪森
Owner IRICO
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