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Lithium ion battery cathode binder, cathode and battery

A lithium-ion battery and binder technology, applied in battery electrodes, adhesives, secondary batteries, etc., can solve the problems of poor cycle stability of lithium-ion batteries, weak adhesion of styrene-butadiene rubber, and binder failure. Good cycle stability, the effect of making up for weak adhesion and preventing shedding

Active Publication Date: 2015-09-02
CHERY AUTOMOBILE CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the bonding ability of styrene-butadiene rubber is weak, and the carbon-carbon double bond will be degraded during the charging and discharging process of the battery, causing the binder to fail.
[0004] In the process of realizing the present invention, the inventors have found that there are at least the following problems in the prior art: the existing lithium-ion battery negative electrode binder cannot well suppress the volume expansion of the silicon-based negative electrode material during charge and discharge, resulting in The cycle stability of lithium-ion batteries is poor

Method used

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  • Lithium ion battery cathode binder, cathode and battery

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Effect test

Embodiment 1

[0056] In the present embodiment, the percentage by weight of each component of the negative electrode material is (in terms of dry material weight):

[0057] Sodium alginate, 4.5%; styrene-butadiene rubber, 0.9%; conductive carbon black, 5%; silicon carbon negative electrode active material, 89.6%. Among them, the number average molecular weight of sodium alginate is about 500,000, and the weight ratio of sodium alginate to styrene-butadiene rubber is 5:1.

[0058] The lithium-ion battery prepared by using the above-mentioned negative electrode material was charged and discharged at a rate of 0.5C at 25°C, and the capacity retention rate was 91% after 200 cycles.

Embodiment 2

[0060] In the present embodiment, the percentage by weight of each component of the negative electrode material is (in terms of dry material weight):

[0061] Sodium alginate, 2%; potassium alginate, 2%; styrene-butadiene rubber, 2%; conductive carbon black, 9%; silicon carbon negative electrode active material, 85%. Among them, the number average molecular weight of sodium alginate and potassium alginate is about 1 million, and the weight ratio of sodium alginate to styrene-butadiene rubber is 2:1.

[0062] The lithium-ion battery prepared by using the above-mentioned negative electrode material was charged and discharged at a rate of 0.5C at 25°C, and the capacity retention rate was 90.6% after 200 cycles.

Embodiment 3

[0064] In the present embodiment, the percentage by weight of each component of the negative electrode material is (in terms of dry material weight):

[0065] Sodium alginate, 1.5%; styrene-butadiene rubber, 1.5%; conductive carbon black, 2%; silicon carbon negative electrode active material, 95%. Among them, the number average molecular weight of sodium alginate is about 50,000, and the weight ratio of sodium alginate to styrene-butadiene rubber is 1:1.

[0066] The lithium-ion battery prepared by using the above-mentioned negative electrode material was charged and discharged at a rate of 0.5C at 25°C, and the capacity retention rate was 91.3% after 200 cycles.

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Abstract

The invention discloses a lithium ion battery cathode binder, a cathode and a battery, and belongs to the technical field of lithium ion batteries. The cathode binder comprises alginate and butadiene styrene rubber, and the weight ratio of alginate to butadiene styrene rubber is 1:1-5:1. According to the invention, through adding alginate in butadiene styrene rubber, the bonding performance of the cathode binder is effectively enhanced. The structural damage of a lithium ion battery caused by the volume expansion of the silicon material during the charging-discharging cyclic process is avoided. Meanwhile, the cyclic stability of the lithium ion battery is improved. In this way, after 200 charge-discharge cycles of the lithium ion battery at the 0.5C multiplying power, the capacity retention ratio of the battery is still kept over 90%.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a lithium ion battery negative electrode binder, negative electrode and battery. Background technique [0002] Lithium-ion batteries have attracted people's attention due to their high energy density and good cycle performance, and have been developed rapidly in the past 20 years. At present, silicon-based anode materials have become the main anode materials for lithium-ion batteries due to their high theoretical specific capacity (4200mAh / g) and abundant sources. However, silicon-based negative electrode materials will undergo huge volume changes during charge and discharge, resulting in rapid capacity fading caused by material structure collapse, which limits the application of silicon-based negative electrode materials. Therefore, it is necessary to use a binder to adhere the silicon-based negative electrode material to the current collector (such as copper foil...

Claims

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Application Information

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IPC IPC(8): C09J105/04C09J109/06H01M4/62H01M10/0525
CPCY02E60/10
Inventor 朱广燕
Owner CHERY AUTOMOBILE CO LTD
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