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Lithium titanate composite negative material for lithium ion battery and preparation method of lithium titanate composite negative material

A lithium-ion battery and negative electrode material technology, applied in battery electrodes, circuits, electrical components, etc., can solve the problems of capacity decay, rapid capacity decay, and reduce the energy density of battery electrodes, to improve specific capacity and rate charge-discharge performance, Process controllable, improve the effect of low conductivity

Active Publication Date: 2015-04-08
河南环宇惠能能源有限公司
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Problems solved by technology

Graphite, as the main negative electrode material for lithium-ion batteries, has the advantages of high theoretical gram capacity, good electronic conductivity, and abundant sources of raw materials, but there are still the following deficiencies: (1) During the initial charge and discharge process, a solid state is formed on the surface of the graphite negative electrode. - Electrolyte interface film SEI, which produces a certain irreversible capacity
[0005] Chinese Patent Publication No. CN102832382 A discloses a method for preparing nano-scale lithium titanate negative electrode materials, which reduces the number of reaction phases and in-situ coating of conductive layers during the reaction to achieve the purpose of inhibiting crystal growth. The titanium produced by this process method Lithium oxide negative electrode material overcomes the shortcomings of the traditional high-temperature solid-phase method, making the lithium titanate material exhibit a narrow distribution at the nanometer level, which improves the rate charge and discharge performance of the material, but the processing performance of the material is poor
However, this method requires more binders to bond the lithium titanate active material to the aluminum foil substrate, which in turn reduces the energy density of the battery electrodes.
[0007] Chinese Patent Publication No. CN103794761 A discloses a method for preparing a silicon / lithium titanate negative electrode material for a lithium ion battery. Lithium titanate is used as a matrix skeleton, and a silicon compound of silicon oxide and other elements is introduced to prepare a two-phase uniform material with High specific capacity and long cycle life Silicon / lithium titanate composite material, the specific capacity of the material can reach more than 500.0mAh / g, but the disadvantage is that the cycle effect is not good, the capacity decays quickly after long-term use, and the retention rate after 100 weeks 82.9%
However, iron disulfide itself has a high expansion rate. After repeated cycles, the intercalation-extraction of lithium ions will cause volume expansion, resulting in rapid capacity decay during the cycle, thereby reducing the effective life of lithium-ion batteries.

Method used

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[0029] In the preparation method of the lithium titanate composite negative electrode material for lithium ion batteries of the present invention, by controlling the ratio of iron powder and sulfur powder, the two are blended, then subjected to high-energy ball milling, and then washed and filtered to obtain high-purity nanometer two iron sulfide. The lithium source, the titanium source and the high-purity nano-iron disulfide are mixed, sintered at high temperature and mechanically fused to form a composite material with lithium titanate as the matrix and nano-iron disulfide as the coating material. Specifically include the following steps:

[0030] 1. Preparation of high-purity nano-iron disulfide, at room temperature (20°C), according to the composition of iron disulfide FeS 2 The molar ratio of the elements, in the iron powder with a particle size of 2.0-10.0μm and the sulfur powder (sulphur element) with a purity of 99.9-99.99%, add FeS 2 The solid dispersant sodium chlo...

Embodiment 1

[0052] One, prepare high-purity nano-iron disulfide, be that the Fe powder 233.0g of 2.0 μm, the purity are 99.95% sulfur powder 267.0g, 12.5gNaCl (accounting for FeS 2 quality 2.5%) in the polytetrafluoroethylene ball milling jar, add 2.5Kg, the zirconia ball milling medium of diameter Φ0.5mm, the mass ratio of grinding medium and mixture is 5:1, under the condition of 200r / min at the rotating speed, Ball milling for 72 hours to obtain iron disulfide FeS 2 material system.

[0053] Iron disulfide FeS 2 Add 4.0Kg of composite detergent solution with a mass concentration of 5.0% to the material system, 33.3g of hydrogen peroxide, 166.7g of sodium borohydride, the mass ratio is 0.2:1, and the mass ratio of the iron disulfide material system to the composite detergent solution is 0.125: 1. Soak for 1.5h, wash with pure water, filter 3 times, dry at 150°C, the purity of iron disulfide is not less than 99.9%, remove the agglomeration by grinding, and obtain high-purity nano-disul...

Embodiment 2

[0060] One, prepare high-purity nanometer iron disulfide, be that the Fe powder 233.0g of 2.0 μm, the purity are 99.95% sulfur powder 267.0g, 25.0gNaCl (accounting for FeS 2 5.0% by mass) in a polytetrafluoroethylene ball mill jar, add 5.0Kg, Φ0.5mm in diameter zirconia zirconia ball milling medium, the mass ratio of the grinding medium to the mixture is 10:1, and the speed is 500r / min , ball milled for 72 hours to obtain iron disulfide FeS 2 material system.

[0061] Iron disulfide FeS 2 Add 0.57Kg of composite detergent solution with a mass concentration of 35.0% to the material system, 100.0g of hydrogen peroxide, 100.0g of sodium borohydride, the mass ratio is 1:1, and the mass ratio of the iron disulfide material system to the composite detergent solution is 0.87: 1. Soak for 2.5 hours, wash with pure water, filter 5 times, dry at 200°C, the purity of iron disulfide is not less than 99.9%, remove the agglomeration by grinding, and obtain high-purity nano-disulfide with ...

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Abstract

The invention discloses a lithium titanate composite negative material for a lithium ion battery and a preparation method of the lithium titanate composite negative material, and aims to improve the specific capacity, conductivity and high-rate charge / discharge characteristics of the negative material for the lithium ion battery. According to the lithium titanate composite negative material for the lithium ion battery disclosed by the invention, lithium titanate serves as a matrix, nano iron disulfide coats the matrix, the amount of the nano iron disulfide is 0.1-10.0 percent of the mass of the matrix, and the granularity of the lithium titanate composite negative material for the lithium ion battery is 0.5-18 microns. The preparation method comprises the following steps: preparing high-purity nano iron disulfide, mixing and sintering. Compared with the prior art, the lithium titanate composite negative material for the lithium ion battery disclosed by the invention has the advantages that the lithium titanate matrix is coated by nano iron disulfide, low conductivity of the lithium titanate material is effectively improved, the specific capacity and high-rate charge / discharge performance of the material are improved, the process is simple, the process flow is controllable, the production cost is low, the environmental pollution is avoided, and the service requirements on power and stored energy lithium ion batteries can be met.

Description

technical field [0001] The invention relates to a new energy material and a preparation method thereof, in particular to a lithium ion battery negative electrode material and a preparation method thereof. Background technique [0002] Since the first commercial application of lithium-ion batteries by Sony Corporation in the 1990s, they have been widely used in electronic equipment and devices due to their high energy density and good safety performance. Graphite, as the main negative electrode material for lithium-ion batteries, has the advantages of high theoretical gram capacity, good electronic conductivity, and abundant sources of raw materials, but there are still the following deficiencies: (1) During the initial charge and discharge process, a solid state is formed on the surface of the graphite negative electrode. - Electrolyte interface film SEI, which produces a certain irreversible capacity. As the cycle continues, the SEI film will continue to change, reducing t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36
CPCH01M4/485H01M4/624Y02E60/10
Inventor 张勇董娇王兴蔚惠国栋
Owner 河南环宇惠能能源有限公司