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Modified silicon carbon negative electrode and preparation method thereof, lithium ion battery

A lithium-ion battery, modified silicon technology, applied in battery electrodes, secondary batteries, electrode manufacturing, etc., can solve problems such as battery capacity loss, and achieve the effects of reducing capacity loss, inhibiting volume expansion, and reducing consumption

Active Publication Date: 2022-02-25
SHENZHEN GRADUATE SCHOOL TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the large volume expansion (>300%) of silicon in the process of intercalating and removing lithium will lead to the pulverization of silicon particles, so that the SEI film on the particle surface is continuously formed and broken, and the solid electrolyte interface (solid electrolyte interface, SEI) film Continuous formation and rupture will continuously consume electrolyte, and the consumption of electrolyte leads to a gradual loss of battery capacity

Method used

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  • Modified silicon carbon negative electrode and preparation method thereof, lithium ion battery
  • Modified silicon carbon negative electrode and preparation method thereof, lithium ion battery

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preparation example Construction

[0026] The invention provides a method for preparing a modified silicon-carbon negative electrode, comprising the following steps:

[0027] Step S10: configuring a mixed nano-silicon solution and placing the mixed nano-silicon solution under an argon atmosphere.

[0028] In this embodiment, "configuring the nano-silicon mixed solution" includes the following steps:

[0029] Step S11: Prepare a mixed solution with alcohol and deionized water.

[0030] Step S12: ultrasonically disperse the nano-silicon powder in the mixed solution to obtain a nano-silicon mixed solution.

[0031] Step S13: adding an acid into the nano-silicon mixed solution to adjust the pH of the nano-silicon mixed solution, and the pH of the nano-silicon mixed solution is 2-5.

[0032] Wherein, an oxide layer is formed on the surface of the nano-silicon powder and has -OH.

[0033] Wherein, the alcohol is at least one of ethanol, isopropanol, n-butanol and the like.

[0034] Wherein, the acid is at least o...

Embodiment 1

[0073] Step 1, mix 50g of absolute ethanol and 20g of deionized water, weigh 1g of nano-silicon powder and add it to the mixed solution of ethanol and water. The particle size of the nano-silicon powder is 30-100nm, and then ultrasonically disperse the nano-silicon powder Evenly, the pH of the mixed solution is adjusted to be 2 with hydrochloric acid to obtain a mixed solution of nano-silicon;

[0074] Step 2: Transfer the nano-silicon mixed solution obtained in Step 1 to a three-necked flask, blow in argon to exhaust the air, then add 0.1g of silane coupling agent KH590, heat to 60°C, and stir for 8 hours to hydrolyze the silane coupling agent to generate active -OH And undergo dehydration condensation with -OH on the surface of nano-silicon, cool, filter, wash, and vacuum-dry to obtain modified nano-silicon grafted with KH590;

[0075] Step 3, mix the modified nano-silicon grafted with KH590 obtained in step 2 and natural graphite with D50=10 μm in a mass ratio of 1:1 as an ...

Embodiment 2

[0078] Step 1: Mix 30g of absolute ethanol and 10g of deionized water, weigh 1g of nano-silicon powder and add it to the mixed solution of ethanol and water. The particle size of the nano-silicon powder is 30-100nm, and then ultrasonically disperse the nano-silicon powder Evenly, adjust the pH of the mixed solution to be 4 with hydrochloric acid;

[0079] Step 2: Transfer the nano-silicon mixed solution obtained in Step 1 to a three-necked flask, blow in argon to exhaust the air, then add 0.2g of silane coupling agent KH590, heat to 70°C, and stir for 10 hours to hydrolyze the silane coupling agent to generate active -OH And dehydration condensation occurs with -OH on the surface of nano-silicon, after cooling, filtering, washing, and vacuum drying, the modified nano-silicon grafted with KH590 is obtained;

[0080] Step 3, mix the modified nano-silicon grafted with KH590 obtained in step 2 and natural graphite with D50=10 μm in a mass ratio of 1:1 as an active material for the...

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Abstract

A method for preparing a modified silicon-carbon negative electrode, comprising: configuring a nano-silicon mixed solution; preparing modified nano-silicon: adding a silane coupling agent to the nano-silicon mixed solution; heating and stirring, so that the silane coupling agent is grafted on the nano-silicon Above; mix the modified nano-silicon and carbon source as an active material to make a silicon-carbon negative electrode, assemble a lithium-ion battery with the silicon-carbon negative electrode as the negative electrode, and add electrolyte additives and initiators to the electrolyte of the lithium-ion battery; by clicking The reaction connects the electrolyte additive to the surface of the modified nano-silicon; and the lithium-ion battery is charged and discharged, and the electrolyte additive connected to the modified nano-silicon is reduced and decomposed to form an SEI film; the SEI film and the silicon-carbon negative electrode constitute Modified silicon carbon anode. The invention also provides a modified silicon carbon negative electrode and a lithium ion battery. The modified silicon-carbon negative electrode provided by the invention and its preparation method, as well as the lithium ion battery have good cycle and rate performance, high specific capacity and simple preparation method.

Description

technical field [0001] The invention relates to the technical field of lithium-ion batteries, in particular to a modified silicon-carbon negative electrode, a preparation method of the modified silicon-carbon negative electrode and a lithium-ion battery. Background technique [0002] Lithium-ion batteries have been widely used in consumer electronics and electric vehicles due to their advantages of high capacity and long cycle life. At present, the commercial negative electrode material is mainly graphite, which has high specific capacity (372mAh / g), low cost, low working potential and good safety, and is widely used in power batteries and mobile phone batteries. However, the continuous improvement of electric vehicles' requirements for cruising range also creates higher requirements for battery energy density. The mature and applied positive and negative electrode materials can no longer meet the development needs due to their low specific capacity. Silicon has the highest...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/1395H01M4/04H01M4/134H01M10/0525
CPCH01M4/1395H01M4/0438H01M4/134H01M10/0525Y02E60/10
Inventor 康飞宇赵亮贺艳兵张丹丰王翠翠陈立坤游从辉
Owner SHENZHEN GRADUATE SCHOOL TSINGHUA UNIV