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Graphitic cladding method by nano-scale mesophase asphalt

A kind of mesophase pitch and nano-scale technology, applied in the direction of electrode manufacturing, etc., can solve the problems of poor compactness of the purification membrane, reduce the cycle life of high-current charge and discharge, and easy bonding of graphite particles, so as to improve the uniformity of coating and the integrity of the spherical shape Degree, reduce the first irreversible capacity, improve the effect of cycle stability

Inactive Publication Date: 2008-10-15
晟茂(青岛)先进材料有限公司
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  • Abstract
  • Description
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  • Application Information

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Problems solved by technology

Therefore, the resulting purification membrane has poor compactness. During the charging process, the co-intercalation of solvated lithium ions is prone to occur, causing the expansion and collapse of the graphite layer and increasing the irreversible capacity.
In addition, after natural graphite is treated by physical or chemical methods, it has the disadvantage of poor bonding performance with the plate, and it is easy to fall off from the plate during cycle charge and discharge, which affects the cycle life, especially reduces the high current charge and discharge. cycle life
[0004] In order to improve the electrochemical properties of natural graphite materials, people have carried out physical and chemical modification and surface modification of natural graphite through various methods, and achieved corresponding effects, such as pulverizing, grading and processing natural graphite into spherical particles, improving the Tap density, in addition, various surface modification methods are used to improve the electrochemical properties of graphite, such as Japanese Patent No. 2000-261046 discloses a thermal oxidation treatment of graphite powder to change the surface state of graphite powder, although Improved reactivity of negative electrode material with electrolyte, but lower discharge capacity than natural graphite
U.S. Pat. No. 6403259 discloses a carbon material coated with ground natural graphite or artificial graphite, which improves the high-temperature self-discharge performance and low-temperature performance of the negative electrode material, but the performance in other aspects is not satisfactory
In addition, U.S. Pat. No. 5908715 uses organic solvents to dissolve epoxy resin and poly-p-phenylene to coat pyrolytic carbon on the surface of graphite. Chinese patent CN1224251A uses ethanol to dissolve phenolic resin or urea-formaldehyde resin to coat graphite. Chinese patent CN1304187A Coating graphite with organic solvent solutions such as polyacrylonitrile, polyvinylidene fluoride, epoxy resin, etc., the above method has environmental pollution, graphite particles after coating are easy to bond, and the coating layer is easy to fall off in the subsequent pulverization process. Damaged, affecting the overall performance of the negative electrode material
[0005] The above coating methods are often uneven due to the large molecular size of the coating and the failure to shape the graphite powder below 15 μm into a spherical shape.
[0006] The use of nano-scale materials to coat graphite to form secondary battery negative electrode materials and the preparation method of this material has become an important way to solve the above problems. As mentioned in Chinese patent CN1670991, natural graphite is modified by quasi-one-dimensional nano-carbon materials, but this The patent application does not provide a specific negative electrode material product formed by combining a specific mesophase material with graphite, nor does it provide a specific preparation method for how to effectively combine nano-carbon materials with graphite substrates

Method used

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  • Graphitic cladding method by nano-scale mesophase asphalt
  • Graphitic cladding method by nano-scale mesophase asphalt
  • Graphitic cladding method by nano-scale mesophase asphalt

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] The equipment composition of this example is as attached Figure 4 shown. The whole set of equipment is connected through pipelines and is in a fully sealed state. Among them, the nano-grinding machine is DRAIS PML-H / V universal nano-grinding machine.

[0027] First, 75 kilograms of natural microcrystalline graphite 2 are put into the high-temperature reactor 6, and the high-temperature reactor is filled with a mixed gas of helium, neon, and argon. Heating rate: Heating for 4 hours, the temperature in the high-temperature reactor was raised to 400°C. Natural microcrystalline graphite is dried in a high-temperature reactor, and a very small amount of pollutants is also burned clean. After 4 hours of heating, cool the high-temperature reactor to 240°C, which is close to but not more than the softening point of the nano-scale mesophase pitch, so that the natural microcrystalline graphite and the sprayed nano-scale mesophase pitch droplets can Better mix coverage.

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Embodiment 2

[0034] The drying of graphite micropowder in this embodiment, the formation of nano-scale mesophase pitch and semi-liquidization, the mixing and coating of nano-scale mesophase pitch and graphite micropowder are the same as in Example 1, but when the coated graphite is carbonized, The carbonization temperature is 1250°C, and the graphitization temperature is 2800°C. The obtained coated graphite powder is used as a negative electrode material for secondary batteries. Its initial charge capacity (mAh / g) is 390.52, and its initial discharge capacity (mAh / g) is 368.51. The 500-cycle capacity retention was 86.5%.

Embodiment 3

[0036] The drying of graphite micropowder in this embodiment, the formation of nano-scale mesophase pitch and semi-liquidization, the mixing and coating of nano-scale mesophase pitch and graphite micropowder are the same as in Example 1, but when the coated graphite is carbonized, The carbonization temperature is 1300°C, and the graphitization temperature is 3000°C. The obtained coated graphite powder is used as a negative electrode material for secondary batteries. Its initial charge capacity (mAh / g) is 388.40, and its initial discharge capacity (mAh / g) is 369.32. The 500-cycle capacity retention was 88.1%.

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Abstract

The invention relates to a preparation method for secondary battery cathode material, more particularly to a preparation method thereof which is formed by coating graphite by using nano-intermediate phase asphalt. The key point of the method is that nano-processing is carried out to the intermediate phase asphalt which is in semi-liquid state, the nano-intermediate phase asphalt in the semi-liquid state is sprayed on the substrate surface of the graphite by a nano-spray device, then even coating is realized, finally, the secondary battery cathode material is obtained by the traditional processes of drying, carbonization and graphitization. The adoption of the method can improve the coating evenness and the spherical completeness in a greater degree, thus further reducing the first-time irreversible capacity of the graphite, improving the cyclical stability and having the advantages that the charging and discharging voltage of the secondary battery is low, the charging and discharging platform is long and the cycle life is good.

Description

technical field [0001] The invention relates to a preparation method of a secondary battery negative electrode material, in particular to a preparation method of a secondary battery negative electrode material formed by coating graphite with nano-scale mesophase pitch. Background technique [0002] The secondary battery is a new generation of battery since the 1990s after the nickel-metal hydride battery, represented by the lithium-ion battery, because of its high working voltage, high energy density, long cycle life, small self-discharge, and no memory effect And other advantages, it has become the preferred chemical power source for high-end electronic consumer products, and has penetrated into aerospace, military and other cutting-edge technology fields. Accompanied by its increasing demand, secondary batteries are becoming the focus and focus of scientific and technological research and development in the new century. [0003] Among them, natural graphite is widely used...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/04
CPCY02E60/10
Inventor 耿世达
Owner 晟茂(青岛)先进材料有限公司
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