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Method for preparing composite material of lithium ion battery cathode, and cathode and battery

A lithium ion battery and composite material technology, which is applied to the preparation of composite materials for lithium ion battery negative electrodes and the fields of negative electrodes and batteries, can solve problems such as poor cycle performance and discharge capacity, achieve high lithium intercalation capacity, improve cycle performance, reduce effect of possibility

Active Publication Date: 2009-05-27
BYD CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to overcome the disadvantages of poor cycle performance and discharge capacity of lithium-ion batteries made of existing silicon-based negative electrode materials for lithium-ion batteries, and to provide a lithium-ion battery that can improve cycle performance and charge-discharge capacity of lithium-ion batteries. Preparation method of composite material for negative electrode of ion battery

Method used

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preparation example Construction

[0024] The preparation method of the negative electrode provided by the present invention comprises mixing the ion battery negative electrode active material provided by the present invention, a binder and a solvent, coating and / or filling on the conductive substrate, drying, calendering or non-calendering, that is The negative electrode can be obtained.

[0025] Described solvent can be selected from N-methylpyrrolidone (NMP), dimethylformamide (DMF), diethylformamide (DEF), dimethylsulfoxide (DMSO), tetrahydrofuran (THF) and water and One or more of alcohols. The amount of the solvent can make the paste have viscosity and fluidity, and can be coated on the conductive substrate. Generally, based on the weight of the negative electrode active material, the content of the solvent is 50-150% by weight, preferably 70-120% by weight.

[0026] The drying and calendering methods and conditions are well known to those skilled in the art. For example, the drying temperature is gene...

Embodiment 1

[0039] This embodiment is used to illustrate the preparation method of the composite material for lithium ion battery negative electrode provided by the present invention.

[0040] Prepare 500mL ethanol aqueous solution, the ratio of ethanol and water is 1:3.5 by volume, add 50g sucrose and stir to dissolve completely, then add 16 grams of silicon powder (particle size range is 1-5 micron, purchased from Beijing Institute of Nonferrous Metals ), 3 grams of silicon powder with a particle size range of 20-40 nanometers (purchased from Zhongzhang International) and 35 grams of artificial modified graphite (with a particle size range of 1-5 microns, purchased from Shenzhen Beitrui), and stirred evenly. Then bake in an oven at 100°C for 12 hours. The dried mixture was sintered in a high-temperature furnace at 650°C under the protection of argon for 10 hours, and then ball-milled in a planetary ball mill with a ball-to-material weight ratio of 200:1 and a speed of 300 rpm for 20 hou...

Embodiment 2

[0042] This embodiment is used to illustrate the preparation method of the composite material for lithium ion battery negative electrode provided by the present invention.

[0043] According to the same method as in Example 1, a composite material A2 for lithium ion battery negative electrodes was obtained. The difference is that 45 grams of sucrose, 15 grams of micro-silica powder (with a particle size range of 1-5 microns), 5 grams of nano-silica powder (with a particle size range of 20-40 nanometers) and 35 grams of artificial modified silicon powder were added to the ethanol aqueous solution. Graphite (particle size range is 1-5 micron), obtains 65 grams of negative electrode active material A2.

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Abstract

The invention relates to a method for preparing a composite material for a cathode of a lithium ion battery, and the cathode and the battery which comprise the cathode material. The preparation method comprises: uniformly mixing silicon powder, graphite, pyrolytic carbon precursor and a solvent to prepare slurry, wherein the silicon powder comprises micro-silicon powder and nano-silicon powder, and the weight ratio of the micro-silicon powder and the nano-silicon powder is 2-20:1; and removing the solvent in the slurry, performing primary sintering under the protection of inert gas, performing primary ball grinding, performing secondary sintering under the protection of the inert gas, and performing secondary ball grinding, wherein the temperature of the secondary sintering is higher than that of the primary sintering. The battery made from the composite material for the cathode of the lithium ion battery obtained by the method has good cycling performance and charge and discharge capacity.

Description

technical field [0001] The invention relates to a preparation method of a composite material for negative poles of lithium ion batteries, as well as negative poles and batteries comprising the negative pole materials. technical background [0002] Lithium-ion batteries have been widely researched and used due to their high working voltage, high energy density, good safety, light weight, and no pollution. Due to the low theoretical specific capacity of carbon materials generally used as negative electrode materials, which is only 372mAh / g, the development space is very limited, so the development of new negative electrode materials is very necessary. The use of silicon as a lithium-ion battery material, with a theoretical reversible capacity of 4400mAh / g, has attracted people's attention. However, studies have found that when silicon powder is used as the negative electrode material, the volume of the particles changes greatly during the charge and discharge process, resulti...

Claims

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Application Information

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IPC IPC(8): H01M4/36H01M4/04B01J19/00H01M4/02H01M10/36
CPCY02E60/12Y02E60/10
Inventor 魏剑锋沈菊林
Owner BYD CO LTD
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