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Composite binder, silicon-based negative electrode plate and preparation method thereof

A silicon-based negative electrode and binder technology, applied in the direction of negative electrodes, electrode manufacturing, battery electrodes, etc., can solve the problems of poor battery cycle performance, electrode structure deformation, and reduced adhesion, so as to improve the rate performance and cycle performance. Effects of life, improvement of performance, and reduction of defective rate

Active Publication Date: 2019-10-18
DONGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although traditional PVDF (molecular weight is about 1 million) has good electrochemical stability and excellent flexibility, it tends to swell when it interacts with propylene carbonate in the electrolyte, resulting in deformation of the electrode structure. Reduced, leading to poor cycle performance of the battery, which limits the application of PVDF in inhibiting the expansion of silicon-based negative electrodes

Method used

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  • Composite binder, silicon-based negative electrode plate and preparation method thereof
  • Composite binder, silicon-based negative electrode plate and preparation method thereof
  • Composite binder, silicon-based negative electrode plate and preparation method thereof

Examples

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Effect test

Embodiment 1

[0048] A preparation method of a high-performance composite binder and a silicon-based negative electrode sheet, the specific steps are:

[0049] (1) Weigh 3g of composite polyvinylidene fluoride powder and put it in a ball mill. The composite polyvinylidene fluoride powder is composed of polyvinylidene fluoride powder with a weight average molecular weight of 2,200,000 and 1,050,000, respectively, with a mass ratio of 7:3, and then 1200r·min -1 The speed is mixed by a ball mill to prepare a composite binder.

[0050] (2) Add the composite binder prepared in step (1) to N-methylpyrrolidone, at a temperature of 25°C, at 1100r·min -1 Stir at a rotating speed for 48 hours, so that the composite binder is dissolved in N-methylpyrrolidone, and a binder glue solution with a mass fraction of 5.5% is prepared.

[0051] (3) Add conductive agent Ketjen black to the above glue solution, the mass ratio of glue solution to conductive agent Ketjen black is 18:1, and the temperature is 25°...

Embodiment 2

[0059] A preparation method of a high-performance composite binder and a silicon-based negative electrode sheet, the specific steps are:

[0060] (1) The composite polyvinylidene fluoride powder that takes 3.5g is put in the ball mill, and the composite polyvinylidene fluoride powder is made up of the polyvinylidene fluoride powder that weight-average molecular weight is respectively 2200000 and 1050000, and mass ratio is 4:1, then at 1000r·min -1 The speed is mixed by a ball mill to prepare a composite binder.

[0061] (2) Add the composite binder prepared in step 1 to N-methylpyrrolidone, at a temperature of 15°C, at 1100r·min -1 Stir for 36 hours at a rotating speed, so that the composite binder is dissolved in N-methylpyrrolidone, and a binder glue solution with a mass fraction of 10% is prepared.

[0062] (3) Add conductive agent Ketjen black to the above glue solution, the mass ratio of glue solution to conductive agent is 15:1, and at a temperature of 15°C at 400r min...

Embodiment 3

[0070] A preparation method of a high-performance composite binder and a silicon-based negative electrode sheet, the specific steps are:

[0071] (1) Weigh 4g of composite polyvinylidene fluoride powder and put it in a ball mill. The composite polyvinylidene fluoride powder is composed of polyvinylidene fluoride powders with weight-average molecular weights of 2,200,000, 1,050,000 and 570,000, respectively, with a mass ratio of 3:2: 1, then at 900r·min -1 The speed is mixed by a ball mill to prepare a composite binder.

[0072] (2) Add the composite binder prepared in step 1 to N-methylpyrrolidone, at a temperature of 30°C, at 1000r·min -1 Stir for 30 hours at a rotating speed, so that the composite binder is dissolved in N-methylpyrrolidone, and a binder glue solution with a mass fraction of 8% is prepared.

[0073] (3) Add conductive agent Ketjen black to the above glue solution, the mass ratio of glue solution to conductive agent is 14:1, and at a temperature of 30°C at 4...

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Abstract

The invention provides a composite binder, a silicon-based negative electrode plate and a preparation method thereof. The preparation method of the silicon-based negative electrode plate comprises thefollowing steps of carrying out mixing on polyvinylidene fluoride of different molecular weights through a ball mill, so as to obtain a composite binder; dissolving the composite binder in an organicsolvent to obtain a binder glue solution; dispersing a conductive agent in the binder glue solution to obtain a conductive glue solution; adding silicon-carbon composite material powder and the organic solvent into the conductive glue solution to prepare electrode slurry; coating the electrode slurry on a negative current collector, and carrying out vacuum high-temperature desolventizing treatment on the current collector coated with the electrode slurry; and carrying out roll pressing on the obtained negative electrode plate to obtain the silicon-based negative electrode plate. According tothe prepared silicon-based negative electrode plate, the performance of a lithium battery electrode material can be effectively improved, the rate performance of the battery is improved, and the cyclelife of the battery is prolonged.

Description

technical field [0001] The invention relates to a high-performance composite binder, a silicon-based negative electrode sheet based on the binder and a preparation method thereof, belonging to the technical field of energy storage batteries. Background technique [0002] Lithium-ion batteries have high energy density, high working voltage, no memory effect, and long cycle life, and are widely used in smart wearable devices and new energy vehicles. However, due to the complex application conditions of lithium-ion batteries, people put forward higher requirements for their energy density, cycle life, and safety performance. Research and development of high energy density silicon negative electrode (theoretical specific capacity 4200mAh g -1 ) to replace the current graphite negative electrode (theoretical specific capacity 372mAh g -1 ) is an important way to improve the performance of lithium-ion batteries. However, during the charging and discharging process, the volume o...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/62H01M4/1395H01M4/1393H01M4/04H01M10/0525
CPCH01M4/623H01M4/1395H01M4/1393H01M4/0404H01M10/0525H01M2004/027Y02E60/10
Inventor 闫建华张逸俊王啸张苑苑李光俞建勇丁彬
Owner DONGHUA UNIV
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