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Crosslinkable negative electrode binder composition, negative electrode active material slurry, negative electrode, negative electrode preparation method and lithium ion battery

A technology of negative electrode active material and composition, which is applied in the field of binders for negative electrode materials of lithium ion batteries, can solve problems such as poor battery cycle performance, and achieve the effect of having both strength and elasticity and good elasticity

Active Publication Date: 2021-06-18
BYD CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The purpose of the present invention is to overcome the problem of poor cycle performance of batteries using polyacrylic acid type binders, to provide crosslinkable binder compositions for negative electrodes, negative electrode active material slurry, negative electrodes, negative electrode preparation methods and lithium ion batteries

Method used

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  • Crosslinkable negative electrode binder composition, negative electrode active material slurry, negative electrode, negative electrode preparation method and lithium ion battery
  • Crosslinkable negative electrode binder composition, negative electrode active material slurry, negative electrode, negative electrode preparation method and lithium ion battery
  • Crosslinkable negative electrode binder composition, negative electrode active material slurry, negative electrode, negative electrode preparation method and lithium ion battery

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preparation example Construction

[0048] A fourth aspect of the present invention provides a method for preparing a negative electrode, comprising:

[0049] (1) Mixing an aqueous solution containing polyacrylic acid polymer and polyol crosslinking agent with conductive agent and active material to obtain a dispersion;

[0050] (2) mixing the dispersion with the carboxyl-containing elastomer and sieving to obtain a slurry;

[0051] (3) Coating the slurry on the current collector and performing drying and baking to form a negative electrode active material layer to obtain a negative electrode.

[0052] In some embodiments of the present invention, preferably, the drying temperature is 80-120° C.; the baking is carried out at 130-180° C. for 1-10 hours under vacuum conditions.

[0053] The polyacrylic polymer, polyol cross-linking agent, and carboxyl-containing elastomer are as described above, and will not be repeated here.

[0054] In some embodiments of the present invention, the polyacrylic acid polymer, po...

Embodiment 1

[0066] Get 1.8g polyacrylic acid (weight average molecular weight is 200,000), 0.4g polyvinyl alcohol (weight average molecular weight is 35,000, degree of alcoholysis is 88%), dissolves in water together; After dissolving completely, add 1g conductive carbon black Super_P Stir and disperse with 0.1g carbon nanotube CNT for 0.5h, rotating speed 2000rpm; Add 15g silicon oxide SiOx powder and 85g natural graphite successively, continue to stir and disperse for 1.5h, rotating speed 2000rpm; The molar percentage of carboxylated styrene-butadiene rubber emulsion is 5%, the molar ratio of butadiene unit to styrene unit is 7:3; the weight average molecular weight of carboxylated styrene-butadiene rubber is 1.5 million; the solid content of carboxylated styrene-butadiene rubber emulsion is 50wt %), stirring 1h, rotating speed 1200rpm;

[0067] Pass the prepared slurry through a 150-mesh sieve, coat it on Cu foil, and bake it at 100°C; bake the dried negative electrode sheet in a vacuu...

Embodiment 2

[0070] According to the method of embodiment 1, the difference is that with carboxylated styrene-butadiene rubber emulsion (wherein, carboxyl accounted for the molar percentage of total carboxylated styrene-butadiene rubber emulsion is 10%, and the mol ratio of butadiene unit and styrene unit is 7:3 The weight-average molecular weight of carboxylated styrene-butadiene rubber is 1,500,000; The solid content of carboxylated styrene-butadiene rubber emulsion is 50wt%), replaces carboxylated styrene-butadiene rubber emulsion (wherein, carboxyl accounts for the mol percentage of total carboxylated styrene-butadiene rubber emulsion is 5%, The molar ratio of the butadiene unit to the styrene unit is 7:3; the weight average molecular weight of the carboxylated styrene-butadiene rubber is 1.5 million; the solid content of the carboxylated styrene-butadiene rubber emulsion is 50 wt%).

[0071] Prepare the negative electrode sheet S2.

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Abstract

The invention relates to the field of binders for negative electrode materials of lithium ion batteries, and discloses a crosslinkable negative electrode binder composition, a negative electrode active material slurry, a negative electrode, a negative electrode preparation method and a lithium ion battery. The crosslinkable negative electrode binder composition comprises a polyacrylic acid polymer, a carboxyl-containing elastomer and a polyhydric alcohol cross-linking agent, wherein hydroxyl groups contained in the polyhydric alcohol cross-linking agent react with carboxyl groups contained in the polyacrylic acid polymer and carboxyl groups contained in the carboxyl-containing elastomer to generate ester groups, and the polyhydric alcohol cross-linking agent can be connected with the polyacrylic acid polymer and the carboxyl-containing elastomer to form a cross-linked polymer. The cross-linked polymer formed by the composition has both strength and elasticity, and overcomes the influence of expansion and shrinkage on the silicon negative electrode.

Description

technical field [0001] The invention relates to the field of binders for lithium ion battery negative electrode materials, in particular to a crosslinkable negative electrode binder composition, negative electrode active material slurry, negative electrode, negative electrode preparation method and lithium ion battery. Background technique [0002] Silicon has become a research hotspot in recent years as a new generation of high energy density lithium-ion battery anode materials. However, silicon will produce a huge volume change during the cycle, which will lead to the pulverization of silicon particles, which will lead to the loss of electrical contact between silicon particles and the conductive agent, destroying the entire electrode structure, resulting in capacity attenuation and poor cycle performance. This limits the good performance of silicon in lithium-ion batteries. Although the modified silicon-based materials can effectively relieve the mechanical strain caused...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/62H01M4/66H01M10/0525
CPCH01M4/621H01M4/622H01M10/0525H01M4/667Y02E60/10
Inventor 钟毅杨吉祥潘仪
Owner BYD CO LTD
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