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Three-dimensional silicon-carbon composite negative electrode material and preparation method and application thereof in lithium ion battery

A silicon-carbon composite and negative electrode material technology, which is applied in the preparation/purification of carbon, negative electrodes, secondary batteries, etc., can solve the problems of battery first-time efficiency drop, small shaping strain, carbon layer rupture, etc., and achieve simple preparation methods High efficiency, good plastic strain, excellent plastic strain effect

Active Publication Date: 2020-07-31
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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  • Three-dimensional silicon-carbon composite negative electrode material and preparation method and application thereof in lithium ion battery
  • Three-dimensional silicon-carbon composite negative electrode material and preparation method and application thereof in lithium ion battery
  • Three-dimensional silicon-carbon composite negative electrode material and preparation method and application thereof in lithium ion battery

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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 as well as a preparation method and application thereof in a lithium ion battery. The preparation methodcomprises the following steps: step 1, freeze-drying bacterial cellulose hydrogel to obtain aerogel, then soaking the aerogel in a nano-silicon source dispersion liquid, and drying after sufficient absorption to obtain bacterial cellulose / nano-silicon composite aerogel; and 2, carrying out high-temperature cracking on the bacterial cellulose / nano-silicon composite aerogel in an inert atmosphere at a high-temperature cracking temperature of 700-1200 DEG C, and naturally cooling to obtain the three-dimensional silicon-carbon composite negative electrode material; the three-dimensional carbon nanofibers derived from bacterial cellulose after carrying out high-temperature cracking are interlinked, and has good shaping strain and excellent mechanical properties, and the obtained three-dimensional carbon nanofiber has a porous network structure, so that the three-dimensional carbon nanofiber can fully accommodate volume expansion of a silicon-based material in charging and discharging processes, and the cycle and rate performance of the material is further improved.

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 Applications(China)
IPC IPC(8): C01B32/05C01B33/02H01M4/36H01M4/38H01M4/62H01M10/0525
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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