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Silicon/graphite compound cathode material and preparation method thereof

A technology of negative electrode material and graphite, which is applied in the field of silicon/graphite composite negative electrode material and its preparation, can solve the problems of contact and separation of electrode material and current collector, capacity attenuation of silicon-based negative electrode battery, low electronic conductivity, etc., so as to improve electronic conductivity. high rate, improved rate performance, and high degree of nanometerization

Active Publication Date: 2018-01-09
GUANGDONG DYNAVOLT NEW ENERGY TECH CO LTD
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  • Abstract
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  • Application Information

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Problems solved by technology

[0004] However, when silicon is used as a negative electrode material, a huge volume change (greater than 300%) occurs during the lithium intercalation process, which leads to the detachment of the electrode material from the current collector , pulverization and other problems, which lead to a sharp decline in the capacity of the silicon-based negative electrode battery
In addition, the intrinsic electronic conductivity of silicon is low, and it is necessary to add a conductive network to improve the electronic conductivity of the entire electrode.

Method used

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  • Silicon/graphite compound cathode material and preparation method thereof
  • Silicon/graphite compound cathode material and preparation method thereof
  • Silicon/graphite compound cathode material and preparation method thereof

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preparation example Construction

[0046] The invention provides a method for preparing a silicon / graphite composite negative electrode material, comprising:

[0047] A) mixing graphite, silicon and binder to obtain a mixture; the mass ratio of graphite and silicon is (1.5-2.5): (1.5-2.5);

[0048] B) mixing the mixture with a dispersant, ball milling, and drying to obtain a silicon / graphite composite negative electrode material.

[0049] The preparation method of the silicon / graphite composite negative electrode material provided by the invention first mixes graphite, silicon and a binder to obtain a mixture.

[0050] According to the present invention, the mixing preferably specifically includes: mixing graphite and silicon first, and then mixing with the binder.

[0051] In the present invention, the source of the graphite is not limited, and it can be commercially available; the particle size of the graphite is also not limited, and graphite particles of 5-50 μm are preferred.

[0052] The present inventi...

Embodiment 1

[0079] Mix 2g of graphite and 2g of silicon evenly; add 0.4g of CMC on the basis of this mixture; put the mixture into a high-energy ball mill jar, then add 10ml of isopropanol as a dispersant, set the ball milling speed to 750 rpm, and set the grinding program Stop for 10 minutes for 10 mills, and 3 hours for ball milling. The product was dried in an oven at 80 °C for 12 h at constant temperature. After drying, it is a step of pickling, which can be pickled with dilute hydrochloric acid with a concentration of 9.5%, to obtain a silicon / graphite composite negative electrode material.

Embodiment 2

[0081] Mix 1.5g of graphite and 1.5g of silicon evenly; add 0.3g of CMC on the basis of this mixture; put the mixture into a high-energy ball mill tank, then add 10ml of isopropanol as a dispersant, set the ball milling speed to 800 rpm, set The grinding procedure is 5 minutes of grinding and 2 hours of ball milling. The product was dried in an oven at 70°C for 11 h at constant temperature. After drying, it is a step of pickling, which can be pickled with dilute hydrochloric acid with a concentration of 9.5%, to obtain a silicon / graphite composite negative electrode material.

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Abstract

The invention provides a preparation method of a silicon / graphite compound cathode material. The preparation method comprises steps of A) mixing graphite, silicon and adhesive, so as to obtain a mixture, wherein a mass ratio of graphite to silicon is (1.5-2.5):(1.5-2.5); B) mixing the mixture and a dispersing agent, ball milling, and drying to obtain the silicon / graphite compound cathode material.According to the preparation method of the silicon / graphite compound cathode material, silicon and graphite are mixed according to a specific proportion and then are ball milled so as to prepare thecathode material, so that the electronic conductivity of an electrode is improved; further, the adhesive is uniformly distributed onto the surface of silicon particles in ball milling, so as to coverand protect the silicon particles effectively, so that nano silicon is less oxidized, the silicon particles are stabilized, the cycle life of the battery is prolonged, and rate performance of the battery is improved.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a silicon / graphite composite negative electrode material and a preparation method thereof. Background technique [0002] The theoretical capacity (372mAh g -1 ) is low, which is greatly restricted when high energy density applications are required. [0003] In addition, the kinetics of graphite is poor, and its lithium intercalation platform is close to metal lithium, which is prone to "lithium separation" phenomenon during fast charging, causing internal short circuit of the battery and causing safety problems. Silicon anode has a high theoretical capacity (4200mAh g-1) and a slightly higher lithium intercalation platform (0.3V) than graphite, so it has unique advantages in terms of high energy density and safety. [0004] However, when silicon is used as a negative electrode material, a huge volume change (greater than 300%) occurs during the lithium intercalati...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/62H01M10/0525B82Y30/00
CPCY02E60/10
Inventor 陈乐伍刘丹
Owner GUANGDONG DYNAVOLT NEW ENERGY TECH CO LTD
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