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Lithium ion battery cathode and preparation method thereof

A lithium ion battery and negative electrode technology, applied in the field of lithium ion battery negative electrode and its preparation, can solve problems such as decrease in charge and discharge capacity, battery failure, loss of electrical contact, etc., and achieve the effects of good cycle performance and large reversible capacity

Inactive Publication Date: 2009-01-21
SHANGHAI JIAO TONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] For lithium-ion battery anode materials with a large volume effect, during the charging and discharging process, the negative electrode active material will undergo a huge volume change, resulting in material powdering and exfoliation, between material particles and between the material and the rigid metal current collector. Loss of electrical contact, resulting in a sharp drop in charge and discharge capacity, and the battery will fail quickly

Method used

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  • Lithium ion battery cathode and preparation method thereof
  • Lithium ion battery cathode and preparation method thereof
  • Lithium ion battery cathode and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0035] (1) Mix and stir 0.85g carbon-coated silicon with 0.05g conductive carbon black, 10g styrene-butadiene rubber-carboxymethylcellulose sodium emulsion (solid content 1wt%) for 6 hours, and then apply to 20 micron thick porous poly On the surface of the vinyl film, vacuum-dry at 40°C for 8 hours to obtain a carbon-coated silicon layer;

[0036] (2) Mix and stir 0.9g acetylene black and 10g styrene-butadiene rubber-sodium carboxymethyl cellulose emulsion (solid content 1wt%) for 4 hours, then apply it to the surface of the carbon-coated silicon layer, and dry it in vacuum at 50°C for 10 hours , to obtain a lithium ion battery negative electrode.

[0037] The prepared lithium-ion battery negative electrode was assembled into a lithium-ion battery for charging and discharging tests. The charging and discharging curves of the first three times were as follows: figure 2 As shown, the capacity-cycle number curve of the first 20 cycles is as follows image 3 shown. Its first ...

Embodiment 2

[0039] (1) Mix and stir 0.85g carbon-coated silicon with 0.05g conductive carbon black, 5g styrene-butadiene rubber-carboxymethylcellulose sodium emulsion (solid content 2wt%) for 8 hours, and then apply to 20 micron thick porous poly On the surface of the vinyl film, vacuum-dry at 50°C for 10 hours to obtain a carbon-coated silicon layer;

[0040] (2) 0.88g acetylene black and 6g styrene-butadiene rubber-carboxymethylcellulose sodium emulsion (solid content 2wt%) were mixed and stirred for 6 hours, then uniformly sprayed onto the surface of the carbon-coated silicon layer, and dried in vacuum at 40°C for 12 hours , to obtain a lithium ion battery negative electrode.

[0041] The prepared lithium-ion battery negative electrode was assembled into a lithium-ion battery for charging and discharging tests. The first charge-discharge coulombic efficiency was 88%, and the reversible capacity after 20 cycles was 1000mAh / g.

Embodiment 3

[0043] (1) Mix and stir 0.85g of carbon-coated silicon with 0.05g of conductive carbon black and 5ml of polyvinylidene fluoride in 1-methyl-2-pyrrolidone (concentration: 0.02g / ml) for 8 hours, and then apply to 20 microns On the surface of a thick porous polyethylene film, dry it in vacuum at 40°C for 12 hours to obtain a carbon-coated silicon layer;

[0044] (2) Mix and stir 0.88g acetylene black and 6ml polyvinylidene fluoride in 1-methyl-2-pyrrolidone solution (concentration 0.02g / ml) for 4 hours, and then apply it to the surface of the carbon-coated silicon layer. vacuum drying for 12 hours to obtain a lithium ion battery negative electrode.

[0045] The prepared lithium-ion battery negative electrode was assembled into a lithium-ion battery for charging and discharging tests. The first charge-discharge coulombic efficiency was 55%, and the reversible capacity after 20 cycles was 900mAh / g.

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Abstract

The invention discloses a Li-ion battery cathode and a preparation method thereof. The cathode consists of a flexible collecting-body layer, a carbon-coated silicon layer and a diaphragm bound together. The flexible collecting-body layer is comprised of acetylene black and binding agent; the carbon-coated silicon layer is comprised of carbon-coated silicon, conducting carbon black and binding agent; the diaphragm is a compound membrane composed of porous polyethylene, porous polypropylene or porous polyethylene-polypropylene. Firstly, the carbon-coated silicon layer, the conducting carbon black and the binding agent are made into slurry, and the slurry is coated on the diaphragm surface and dried to achieve the carbon-coated layer; secondly, the slurry containing acetylene black and binding agent is coated on the surface of carbon-coated silicon layer, and a Li-ion battery cathode is achieved after drying. 1mol / L LiPF6 / EC:DMC (volume ratio) is taken as electrolyte and lithium metal is taken as counter electrode to assemble a Li-ion battery with the cathode; a constant-current charging and discharging test is conducted under 0.2mA / cm<2> current density, the first cycling coulomb efficiency reaches 85 percent, and the reversible capacity can reach 1100mAh / g. To the silicon materials with large-volume variation during the charging and discharging process, the cycling stability of the cathode taking acetylene black as the flexible collecting-body layer is much higher compared with the cycling stability of any traditional cathode taking copper foil as collecting-body.

Description

technical field [0001] The invention relates to a battery electrode and a preparation method thereof, in particular to a lithium ion battery negative electrode and a preparation method thereof. Background technique [0002] The internal structure of lithium-ion batteries is usually divided into four parts: positive electrode, negative electrode, separator and electrolyte. Among them, the positive (negative) electrode contains the positive (negative) electrode current collector and active material; the diaphragm is located between the positive electrode and the negative electrode, which insulates the electrons between the positive and negative plates to avoid short circuit; the electrolyte is mainly adsorbed in the diaphragm, which is the lithium ion in the The carrier that moves between the positive and negative plates. [0003] The existing lithium-ion battery negative electrode consists of two parts: a current collector and an active material layer. The current collector...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/02H01M4/04H01M4/66H01M4/36H01M4/62H01M2/14H01M2/16H01M2/18H01M50/40H01M50/403H01M50/417H01M50/463
CPCY02E60/10
Inventor 杨军高鹏飞王久林努丽燕娜
Owner SHANGHAI JIAO TONG UNIV
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