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A three-dimensional silicon-carbon composite negative electrode material and its preparation method and application in lithium-ion batteries

A silicon-carbon composite and negative electrode material technology, which is applied in the preparation/purification of carbon, negative electrodes, battery electrodes, etc., can solve the problems of battery first-time efficiency drop, small shaping strain, capacity attenuation, etc., and achieve a simple and efficient preparation method. Good plastic strain, improve the effect of mass specific capacity

Active Publication Date: 2022-01-25
SHAANXI COAL & CHEM TECH INST
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Problems solved by technology

However, due to the small plastic strain of the carbon material used as the cladding layer, the carbon layer tends to rupture with the volume expansion of the silicon material during the de-lithiation process of the composite material, resulting in full contact between the silicon material and the electrolyte, Continuous formation of the electrolyte interface (SEI) film, causing the first drop in efficiency of the battery and capacity fading in long-term cycling

Method used

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  • A three-dimensional silicon-carbon composite negative electrode material and its preparation method and application in lithium-ion batteries
  • A three-dimensional silicon-carbon composite negative electrode material and its preparation method and application in lithium-ion batteries
  • A three-dimensional silicon-carbon composite negative electrode material and its preparation method and application in lithium-ion batteries

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preparation example Construction

[0028] The preparation method of the three-dimensional silicon-carbon composite negative electrode material of the present invention, such as figure 1 As shown, the specific steps are as follows:

[0029] Step 1. The bacterial cellulose hydrogel is obtained by freeze-drying to obtain an aerogel, and then it is soaked in the nano-silicon source dispersion liquid. The mass concentration of the nano-silicon source dispersion liquid is 1-20%. Liquid nitrogen freeze-drying or supercritical drying to obtain bacterial cellulose / nano-silicon composite airgel;

[0030] Step 2. Pyrolyze the bacterial cellulose / nano-silicon composite airgel obtained in step 1 under an inert atmosphere at a temperature of 700-1200° C. for 0.5-3 hours, and naturally cool to obtain the three-dimensional silicon-carbon composite negative electrode material .

[0031] Nano-silicon source dispersion liquid is obtained by adding one or two mixtures of nano-element silicon powder and nano-silicon oxide powder ...

Embodiment 1

[0034] 1) Cut the bacterial cellulose hydrogel into rectangles (4*2*0.2cm 3 ), and then freeze-dried with liquid nitrogen to obtain bacterial cellulose airgel; add 10 mg of elemental silicon powder with an average particle size of 50 nm into 190 mg of deionized water, fully stir and ultrasonically disperse for 30 min by an ultrasonic breaker to obtain a stable mass concentration 5% nano-silicon source dispersion;

[0035] 2) Immerse the bacterial cellulose airgel in the nano-silicon source dispersion liquid for 30 minutes, rinse off the residual liquid on the surface with deionized water after taking it out, and then freeze-dry it with liquid nitrogen to obtain the bacterial cellulose / nano-silicon composite airgel;

[0036] 3) The bacterial cellulose / nano-silicon composite airgel obtained in step 2 was pyrolyzed at 700° C. for 1 h under nitrogen atmosphere, and then cooled naturally to obtain a three-dimensional silicon-carbon composite negative electrode material.

[0037] S...

Embodiment 2

[0039] 1) Cut the bacterial cellulose hydrogel into rectangles (4*3*1.5cm 3 ), and then freeze-dried with liquid nitrogen to obtain bacterial cellulose airgel; add 30 mg of elemental silicon powder with an average particle size of 80 nm into 270 mg of absolute ethanol, fully stir and ultrasonically disperse for 30 min by an ultrasonic breaker to obtain a stable quality 10% nano-silicon source dispersion;

[0040] 2) Immerse the bacterial cellulose airgel in the nano-silicon source dispersion for 30 minutes, rinse off the residual liquid on the surface with ethanol after taking it out, and then dry it by supercritical to obtain the bacterial cellulose / nano-silicon composite airgel;

[0041] 3) The bacterial cellulose / nano-silicon composite airgel obtained in step 2 was pyrolyzed at 800° C. for 2 hours under an argon atmosphere, and cooled naturally to obtain a three-dimensional silicon-carbon composite negative electrode material.

[0042] Such as Figure 4 As shown, the volu...

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Abstract

The invention provides a three-dimensional silicon-carbon composite negative electrode material and its preparation method and application in lithium-ion batteries. The preparation method comprises the following steps: step 1, the bacterial cellulose hydrogel is freeze-dried to obtain an aerogel, and then the The aerogel is immersed in the nano-silicon source dispersion liquid, fully absorbed and then dried to obtain the bacterial cellulose / nano-silicon composite aerogel; step 2, pyrolyzing the bacterial cellulose / nano-silicon composite aerogel under an inert atmosphere , the pyrolysis temperature is 700-1200°C, and the three-dimensional silicon-carbon composite negative electrode material is obtained after natural cooling. After pyrolysis, the three-dimensional carbon nanofibers derived from bacterial cellulose are cross-linked with each other, which has good plastic strain and endows them with excellent mechanical properties. Moreover, the obtained three-dimensional carbon nanofibers have a porous network structure, so they can fully accommodate The volume expansion of silicon-based materials during charge and discharge improves the cycle and rate performance of the material.

Description

technical field [0001] The invention relates to a three-dimensional silicon-carbon composite negative electrode material, a preparation method thereof and an application in lithium ion batteries, belonging to the field of lithium ion battery negative electrode materials. Background technique [0002] Due to the rapid development and wide application of a variety of portable electronic devices and electric vehicles, there is an urgent need for high-energy, long-cycle-life energy storage batteries. At present, the capacity (~350mAh / g) of commercial lithium-ion battery graphite anode is close to its theoretical capacity (372mAh / g), and there is limited room for improvement. The development of new high-energy anode materials will be an inevitable trend. [0003] Compared with traditional graphite anodes, silicon anodes have been widely studied due to their ultra-high theoretical specific capacity (4200mAh / g) and better safety, and are considered to be one of the most promising n...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/62H01M10/0525C01B32/05C01B33/02
CPCC01B33/02C01B32/05H01M4/366H01M4/386H01M4/625H01M4/628H01M10/0525H01M2004/021H01M2004/027Y02E60/10
Inventor 曹国林田占元沈晓辉曹新龙苏彤杨时峰张长安胥鑫薛孟尧范瑞娟
Owner SHAANXI COAL & CHEM TECH INST
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