Composite graphite negative electrode material for lithium ion secondary cell and its preparation method

A secondary battery and composite graphite technology, applied in the direction of secondary battery, electrode manufacturing, battery electrodes, etc., can solve the problems of low discharge capacity, strong inhomogeneity, poor density of passivation film, etc., and achieve simple process and high discharge capacity High, easily industrializable effect

Active Publication Date: 2005-11-30
BTR NEW MATERIAL GRP CO LTD
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Problems solved by technology

However, due to the high degree of graphitization of natural graphite, the crystal structure and other physical and chemical properties between the edge and bottom of the crystallites are quite different, and the inhomogeneity of the reaction with the electrolyte is strong, and the decomposition reaction of the electrolyte is mainly Occurs at the edge of the crystallite
Therefore, the density of the generated passivation film is poor. During the charging process, the co-intercalation of solvated lithium ions is prone to occur, which causes the expansion and collapse of the graphite layer and increases the irreversible capacity.
In addition, after natural graphite has been 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 the cycle charge and discharge process, which affects the cycle life, especially when the high current charge and discharge is reduced. cycle life
On the other hand, as the negative electrode material of lithium ion battery, natural graphite must be pulverized to increase its surface area to store more lithium. Graphite, as a lubricating material, is prone to interlayer sliding, resulting in the change and destruction of the crystal structure of graphite during the crushing process, which affects the charge-discharge capacity and high-current charge-discharge performance of graphite materials, and limits the use of natural graphite anode materials. widely used
[0003] In order to improve the electrochemical properties of natural graphite materials, people have carried out...

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  • Composite graphite negative electrode material for lithium ion secondary cell and its preparation method

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preparation example Construction

[0021] The preparation method of the composite graphite negative electrode material of the lithium ion secondary battery of the present invention comprises the following steps: 1. The natural graphite surface is coated with organic matter by liquid phase coating, melting coating and solid phase mixing coating method to obtain coating Graphite; 2. heat-treat the coated graphite at a temperature range of 800°C to 1500°C for 1-6 hours, and fill it with protective gas during heat treatment; 3. After heat treatment, cool down to room temperature, crush and sieve to obtain nuclei, Modified natural graphite with shell structure; 4. Mixing modified natural graphite and artificial graphite according to the mass ratio of 30:70-80:20.

[0022] Organic matter is furan resin, urea-formaldehyde resin, pyrimidine resin, phenolic resin, epoxy resin, polyvinyl alcohol, polystyrene, polymethyl methacrylate, polytetrafluoroethylene, polyvinylidene fluoride, polyacrylonitrile, coke, Coal tar pitc...

Embodiment 1

[0026] High softening point medium temperature petroleum asphalt is crushed to below 3 μm, and the average particle size D 50 =17.931μm, tap density 1.017g / cm 3 , specific surface area 5.3m 2 / g of spherical natural graphite and asphalt powder are fully mixed and bonded, and the mixing mass ratio of asphalt and natural graphite is 1:10; then the above-mentioned coated graphite is heated to 1100 ° C for 2 hours under the protection of nitrogen, and then cooled to room temperature , to obtain coated modified natural graphite, the average particle size D 50 18.4μm, crystal layer spacing d 002 is 0.3358nm. The above-mentioned coated graphite is uniformly mixed with the artificial graphite according to the mass ratio of 50:50 after being pulverized and sieved, as the composite graphite negative electrode material of the lithium ion battery of the present invention, wherein the artificial graphite has an average particle diameter D 50 12.4μm, crystal layer spacing d 002 is 0.33...

Embodiment 2

[0028] Crush the coal tar pitch to less than 3 μm, and the average particle size D 50 =4.8μm, tap density 0.95g / cm 3 , specific surface area 7.5m 2 / g of spherical natural graphite and pitch powder are fully mixed and bonded, and the mixing mass ratio of pitch and natural graphite is 1:10; then the above-mentioned coated graphite is heated to 800°C for 6 hours under the protection of argon, and the temperature is reduced to At room temperature, the coated modified natural graphite was obtained, and its average particle size D 50 5μm, crystal layer spacing d 002 is 0.335nm. The above-mentioned coated graphite is uniformly mixed with the artificial graphite according to the mass ratio of 30:70 after being pulverized and screened, as the composite graphite negative electrode material of the lithium ion battery of the present invention, wherein the artificial graphite has an average particle diameter D 50 2μm, crystal layer spacing d 002 is 0.336nm.

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Abstract

This invention discloses one lithium ion second battery compound negative materials and its process method, wherein, the materials comprise modified natural graphite and artificial graphite with quality proportion of 30í†70í½80í†20 and the process method comprises the following steps: a, the natural graphite surface is covered with organism; b, making the thermal process in temperature range of 800íµí½1500íµ for one to six hours; c, mixing the natural graphite with the artificial graphite as proportion of 30í†70í½80í†20.

Description

technical field [0001] The invention relates to a composite graphite negative electrode material for a lithium ion secondary battery and a preparation method thereof. Background technique [0002] Lithium-ion batteries are a new generation of secondary batteries after nickel-metal hydride batteries since the 1990s. Because of its advantages such as high working voltage, high energy density, long cycle life, small self-discharge, and no memory effect, 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. With its ever-increasing demand, lithium-ion batteries are becoming the focus and focus of scientific and technological research and development in the new century. At present, the anode materials of commercial lithium-ion batteries are all carbon materials, mainly petroleum coke and graphite materials, among which natural graphite is widely used becau...

Claims

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Application Information

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IPC IPC(8): H01M4/58
CPCY02E60/10
Inventor 岳敏王桂林
Owner BTR NEW MATERIAL GRP CO LTD
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