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Negative electrode, lithium ion secondary battery and preparation method of lithium ion secondary battery

A secondary battery, lithium ion technology, used in secondary batteries, negative electrodes, battery electrodes, etc.

Inactive Publication Date: 2021-02-23
MICROVAST POWER SYST CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The object of the present invention is to provide a negative electrode, a lithium ion secondary battery and a preparation method thereof. Through the charging process, the excess lithium ions of the positive electrode are precipitated and deposited in the pores of the negative electrode, so that the lithium metal and the negative electrode active material jointly form the negative electrode. In order to solve the problem of lithium precipitation on the surface of the negative electrode during the battery cycle, prevent the formation of lithium dendrites, thereby improving the safety of the battery

Method used

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  • Negative electrode, lithium ion secondary battery and preparation method of lithium ion secondary battery
  • Negative electrode, lithium ion secondary battery and preparation method of lithium ion secondary battery
  • Negative electrode, lithium ion secondary battery and preparation method of lithium ion secondary battery

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preparation example Construction

[0053] This embodiment also provides a method for preparing a lithium-ion secondary battery as described above, comprising the steps of:

[0054] Mix the first negative electrode active material, conductive agent, binder, hole support material and solvent uniformly to make a negative electrode mixture, and apply the negative electrode mixture on the negative electrode current collector to make a negative electrode sheet; wherein, the hole support material constitutes The conductive network structure of the negative electrode sheet.

[0055] Mix the positive electrode active material, conductive agent, binder and solvent uniformly to make a positive electrode mixture, and apply the positive electrode mixture on the positive electrode current collector to make a positive electrode sheet;

[0056] Assemble the positive electrode sheet, negative electrode sheet, separator and electrolyte into a cell;

[0057] Charge the cell to the upper limit voltage to make lithium ions excessi...

no. 1 example

[0062] 35wt% MCMB (mesophase carbon microspheres), 10wt% conductive carbon black, 30wt% conductive carbon fiber, 25wt% PVDF (polyvinylidene fluoride) and appropriate amount of NMP (N-methylpyrrolidone) were stirred and homogenized The negative electrode material layer, wherein MCMB is used as a first negative electrode active material, conductive carbon black is used as a conductive agent, conductive carbon fiber is used as a hole support material, PVDF is used as a binder, and NMP is used as a solvent.

[0063] Then, the negative electrode material layer is double-sided coated on the negative electrode current collector (area density 160g / cm 2 ), dried in an oven; then rolled and compacted with a compacted density of 0.8g / cc; anode sheets meeting the size requirements were obtained by cutting.

[0064] Figure 2a It is a structural schematic diagram of the conductive network structure under the electron microscope in the first embodiment of the present invention. Please com...

no. 2 example

[0066] Stir 35wt.% of MCMB (mesophase carbon microspheres), 10wt.% of conductive carbon black, 30wt.% of conductive carbon fiber, 25wt.% of PVDF (polyvinylidene fluoride) and appropriate amount of NMP (N-methylpyrrolidone) The homogenate is made into mixture; The mixture is double-sidedly coated on the negative electrode current collector (area density 160g / cm 2 ), dried in an oven; then rolled and compacted with a compacted density of 0.96g / cc; a negative electrode sheet meeting the size requirements was obtained by cutting.

[0067] Figure 2b It is a schematic structural diagram of the conductive network structure under the electron microscope in the second embodiment of the present invention. Please combine Figure 2b , there are also continuous and a large number of conductive holes in the figure, that is to say, the second embodiment of the present invention also constitutes a negative electrode structure that can deposit all lithium metal into the holes in the conduct...

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Abstract

The invention provides a negative electrode. The negative electrode comprises a first negative electrode active material, a conductive network structure with holes and a second negative electrode active material positioned in the holes, the second negative electrode active material is lithium metal, and the lithium metal is deposited in the conductive network structure and is not separated out from the surface of the negative electrode. The invention further provides a lithium ion secondary battery comprising the negative electrode and a preparation method of the lithium ion secondary battery,excessive lithium ions of the positive electrode are separated out and deposited in holes of the negative electrode through a charging process, so that lithium metal and a negative electrode active material jointly form the negative electrode, and the problem of lithium separation on the surface of the negative electrode in a battery circulation process is solved; the formation of lithium dendrites is avoided, so that the safety of the battery is improved; meanwhile, the negative electrode has two charging and discharging forms of lithium metal and graphite with different mechanisms, so thatthe energy density and the cycle performance of the battery are improved.

Description

technical field [0001] The invention relates to a negative electrode for a lithium secondary battery, a lithium secondary battery containing the negative electrode and a preparation method thereof. Background technique [0002] In the past 20 years, lithium-ion batteries, as a new energy industry, have shown rapid development. With the development of lithium battery technology, the performance of lithium ion batteries has become more and more diversified, and gradually entered various fields of production and life. In the field of new energy vehicles, in order to achieve higher mileage, lithium-ion secondary batteries as power sources are required to have higher and higher energy densities. To this end, researchers are working on developing new high-voltage or high-capacity electrode materials. In terms of positive electrodes, the method of increasing the Ni content in ternary materials (NCM, NCA) is usually used to achieve the purpose of increasing the energy density of l...

Claims

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Application Information

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IPC IPC(8): H01M4/134H01M4/36H01M4/38H01M4/583H01M4/62H01M10/0525
CPCH01M4/134H01M4/362H01M4/382H01M4/583H01M4/625H01M10/0525H01M2004/021H01M2004/027Y02E60/10
Inventor 孟嘉锋刘文娟王晓亚陈方平高丽君李思昊
Owner MICROVAST POWER SYST CO LTD
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