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Modification method of natural graphite negative electrode material

A technology of natural graphite and negative electrode material, applied in the direction of negative electrode, battery electrode, active material electrode, etc., can solve the problems of increased surface and bulk defects, increased interlayer spacing, unfavorable electrochemical performance of graphite, etc., to improve rate performance and low temperature performance, the effect of increasing the interplanar spacing

Active Publication Date: 2021-11-12
BEIJING INSTITUTE OF TECHNOLOGYGY +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] At present, there are many graphite material expansion processes reported, mainly through the use of strong oxidants and intercalants such as potassium permanganate, hydrogen peroxide, concentrated sulfuric acid, ammonium persulfate, etc., to introduce small molecules or Oxygen-containing functional groups overcome the van der Waals force between graphite layers through the steric hindrance and electrostatic repulsion of small molecules or oxygen-containing functional groups to increase the interlayer spacing. However, due to the introduction of a large number of oxygen-containing functional groups in this type of process, the conductivity of graphite decreases. , surface and bulk phase defects increase, which is not conducive to the improvement of graphite electrochemical performance

Method used

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  • Modification method of natural graphite negative electrode material
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  • Modification method of natural graphite negative electrode material

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0057] In a glove box filled with argon, mix natural graphite powder and sodium powder at a mass ratio of 100:1, and grind in an agate mortar for 10 min to disperse the powder evenly. The mixed powder was transferred to a tube furnace filled with argon, and the temperature was raised to 300 °C at a rate of 5 °C / min for 1 h, and then cooled with the furnace to obtain a modified natural graphite anode material pre-embedded with Na.

[0058] Figure 4 It is the XRD pattern of modified natural graphite, and the results show that its peak shape is not significantly different from that of Comparative Example 1, and the long-range order is preserved, but the position of the main peak shifts to the left to 26.29°, indicating that the (002) interplanar spacing of graphite increases. Big.

[0059] Figure 5 This is the SEM image of modified natural graphite, and the morphology of natural graphite modified by thermal doping process has no obvious change.

Embodiment 2

[0061] Weigh LiFePO according to the mass ratio of 100:1 4 and Na 2 CO 3 Powder, with absolute ethanol as solvent, ball milled at 450r / min for 30min to mix the powder evenly to obtain large ion premixed LiFePO 4 ; According to the same electrode preparation and CR2025 button battery assembly method as in Comparative Example 2, the LiFePO premixed with large ions was used respectively 4 As the positive electrode, natural graphite is used as the negative electrode to assemble the button battery.

[0062] In the voltage window of 2.5 ~ 3.65V, the constant current charge and discharge tests were carried out on the battery at different current densities. The SEM of the electrode after 300 cycles at a current density of 1C is as follows: Figure 6 As shown, the microscopic morphology of the electrode surface is similar to that of Comparative Example 2. The formation of a solid electrolyte interface film was also observed on the surface, and the thickness did not change significa...

Embodiment 3

[0064] In a glove box filled with argon atmosphere, weigh 1M NaPF 6 , the solvent is 0.8mL electrolyte solution of EC, DEM and EMC mixed solution with a volume ratio of 1:1:1; containing 1M LiPF 6 , the solvent is 20mL of electrolyte solution of EC, DEM and EMC mixed solution with a volume ratio of 1:1:1. The two electrolytes were mixed and stirred thoroughly to obtain Li + and Na + The electrolyte solution with a molar ratio of 100:1 is recorded as No. 1 electrolyte solution.

[0065] The natural graphite pole piece obtained in Comparative Example 1 was used as the working electrode, the lithium metal sheet was used as the counter electrode, and Celgard2500 was used as the separator, and the above-mentioned No. 1 electrolyte was used to assemble a CR2025 button battery in a glove box filled with an argon atmosphere, wherein each The amount of electrolyte used for each battery is 0.08mL.

[0066] Such as Figure 7 As shown, within the voltage window of 0.01-1.5V, under th...

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Abstract

The invention relates to a modification method of a natural graphite negative electrode material, and belongs to the technical field of lithium ion batteries. Natural graphite and alkaline earth metal with a large ion radius are subjected to thermal doping so that the alkaline earth metal elementary substance reaches a molten state and is diffused in the graphite, and the bulk phase doping of the graphite is completed. Or according to the method, large-size alkali metal ions are introduced into the positive electrode material or electrolyte of the battery system in advance, and the large-size ions are pre-embedded into the natural graphite bulk phase in the working process of the battery. According to the method disclosed by the invention, the distance between graphite sheet layers is increased, and the rate capability and the low-temperature performance of natural graphite are improved.

Description

technical field [0001] The invention relates to a method for modifying a natural graphite negative electrode material, belonging to the technical field of lithium ion batteries. Background technique [0002] Since entering the era of industrialization, a large amount of fossil fuels such as coal, oil, and natural gas have been used in people's production and life, and the resulting energy crisis and environmental crisis have become increasingly severe. With people's increasing emphasis on environmental protection and the concept of sustainable development gradually becoming popular, it has become a social consensus to replace traditional fossil fuels with renewable clean energy. In this context, the development of low-cost, high-performance and efficient energy storage devices has become goals pursued by researchers. Lithium-ion batteries stand out among many secondary batteries due to their high energy density, high work efficiency, and long service life. At the same time...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/62H01M4/587H01M10/0525
CPCH01M4/628H01M4/587H01M10/0525H01M2004/027H01M2004/021Y02E60/10
Inventor 李宁陈峒任苏岳锋陈来曹端云马亮董宇卢赟黄擎
Owner BEIJING INSTITUTE OF TECHNOLOGYGY
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