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Cathode active material, preparation method thereof and lithium battery using same

A negative electrode active material, lithium ion battery technology, applied in battery electrodes, secondary batteries, electrode manufacturing, etc., can solve problems such as serious volume effects, achieve high capacity characteristics, increase cycle stability, and improve energy density.

Active Publication Date: 2010-06-16
BYD CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The technical problem to be solved by the present invention is to improve the serious volume effect and pulverization and shedding problems of the existing silicon-based materials during charging and discharging, and improve the cycle performance of the battery

Method used

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Examples

Experimental program
Comparison scheme
Effect test

preparation example Construction

[0026] A preparation method of above-mentioned negative electrode active material, it comprises:

[0027] (1) Mix silicon fiber and carbon fiber ball mill and sinter at high temperature under protective gas to obtain silicon carbon fiber; mix silicon and metal ball mill and sinter at high temperature under protective gas to obtain silicon / metal alloy;

[0028] (2) Mix silicon carbon fiber and silicon / metal alloy, add in dispersant, and ultrasonically disperse to obtain slurry;

[0029] (3) Volatilize the dispersant in the slurry, and treat it at low temperature under protective gas.

[0030] The mixing by ball milling is well known to those skilled in the art. In the present invention, ball milling is preferably carried out by using a planetary ball mill under the protection of an inert gas such as argon.

[0031] The particle size of the mixed silicon and metal balls is controlled between 0.01-100 μm.

[0032] The high temperature sintering is also well known to those skill...

Embodiment 1

[0046] Weigh 100 g of silicon fiber and 200 g of carbon fiber, send them into a planetary ball mill, set the speed at 600 rpm, and ball mill for 120 minutes to obtain a uniformly mixed powder. The obtained powder was treated at a high temperature of 800° C. for 60 minutes under the protection of Ar atmosphere to form silicon carbon fibers.

[0047] Weigh 200 g of silicon powder (5 μm in particle size) and 600 g of iron powder, send them into a planetary ball mill, set the speed at 600 rpm, and mill for 120 minutes to obtain a uniformly mixed powder. The obtained powder was treated at a high temperature of 1000° C. for 180 min under the protection of an Ar atmosphere to form a silicon / metal alloy.

[0048] Weigh 200 g of the silicon carbon fiber and 800 g of the silicon / metal alloy synthesized above, add them into the organic solvent NMP, and disperse them by ultrasonic waves for 200 min to form a slurry. After the slurry was volatilized with the organic solvent, the obtained ...

Embodiment 2

[0050] The difference from Example 1 is that copper powder is used instead of iron powder to obtain negative electrode active material, and the product is marked as G2.

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Abstract

The invention provides a cathode active material used for a lithium ion battery, which comprises a dispersion carrier and a composite material dispersing in the dispersion carrier. The dispersion carrier comprises silicon fibers and carbon fibers; and the composite material is a silicon / metal alloy. The conventional silica-based material has the problems of serious volume effect, pulverization and shedding during electrochemical lithium extraction, which causes poor cycle performance of the battery. The cathode active material can effectively solve the problems of the volume effect, the pulverization and the shedding so as to improve the cycle performance of the battery. The invention also provides a method for preparing the cathode active material, which comprises the following steps of: ball-milling and mixing the silicon fibers and the carbon fibers, and sintering the mixture at high temperature to prepare silicon-carbon fibers; ball-milling and mixing silicon and a metal, and sintering the mixture at the high temperature to prepare the silicon / metal alloy; mixing the silicon-carbon fibers and the silicon / metal alloy, adding the mixture into a dispersing agent, and dispersing the mixture with ultrasonic waves to obtain slurry; and volatilizing the dispersing agent in the slurry, and processing the slurry under a shielding gas at low temperature.

Description

technical field [0001] The invention relates to a negative electrode material, a preparation method thereof, and a lithium battery using the material, in particular to a silicon-based negative electrode active material, a preparation method thereof, and a lithium battery using the material. Background technique [0002] Due to its high voltage, high specific energy, long cycle life and environmental friendliness, lithium-ion batteries have become ideal supporting power sources for various portable electronic and mobile products. [0003] At present, in lithium-ion batteries, carbon-based materials are mostly used for negative poles, such as MCMB, graphite, and organic pyrolytic carbon. Carbon-based materials have good reversible lithium deintercalation performance, but their reversible capacity is low (<372mAh / g), and the lithium intercalation potential is low (0.25-0.05Vvs.Li+ / Li), which is close to the metal lithium potential, while lithium ion diffusion The low speed ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/62H01M4/04H01M10/36
CPCY02E60/12Y02E60/10
Inventor 胡栋杰袁学远姜占锋
Owner BYD CO LTD
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