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Negative electrode material and preparation method and application thereof

A technology of negative electrode material and carbon material, applied in the field of negative electrode material and its preparation, can solve the problems of affecting the stability and integrity of the SEI film on the surface of the negative electrode, deteriorating the long-term service life and capacity retention of the battery cell, removing the film and removing powder, etc. Reliability, improve cycle performance and storage performance, improve the effect of cell expansion

Inactive Publication Date: 2021-06-22
SVOLT ENERGY TECHNOLOGY CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Si / SiO in this literature 2 There is a very large shrinkage and expansion during the charging and discharging process. As the cycle progresses, the negative electrode will have a phenomenon of peeling off the film under a high shrinkage expansion ratio, and at the same time affect the stability and integrity of the SEI film on the surface of the negative electrode, which greatly deteriorates the battery life. Long-term core life and capacity retention

Method used

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  • Negative electrode material and preparation method and application thereof
  • Negative electrode material and preparation method and application thereof
  • Negative electrode material and preparation method and application thereof

Examples

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Embodiment 1

[0047] This embodiment provides a negative electrode material, such as figure 1 As shown, the negative electrode material includes an inner core 1 and a buffer layer coated on the surface of the inner core, the inner core 1 is SiO with a median particle size of 10 μm, and the buffer layer contains a low expansion material 2 and a conductive agent 3 And binding agent 4, described low-expansion material 2 is the natural graphite that median diameter is 2 μm, and described conductive agent 3 is the carbon nanotube that the aspect ratio of diameter is 200nm is 13, and described binding agent 4 is Styrene-butadiene rubber; the mass proportion of the natural graphite is 5%.

[0048] The preparation method of the negative electrode material is as follows:

[0049] SiO, natural graphite, carbon nanotube, styrene-butadiene rubber are stirred 40min with the mass ratio of 93:5:1:1 and water with the stirring linear speed of 70m / min, obtain the mixed slurry that solid content is 50%, at ...

Embodiment 2

[0051] This embodiment provides a negative electrode material, which includes SiO with a median particle size of 8 μm 2 The inner core of the artificial graphite mixed material with a median particle size of 5 μm and a buffer layer coated on the surface of the inner core, wherein the buffer layer includes lithium titanate with a median particle size of 0.5 μm and a long diameter of 50 nm. Carbon nanotubes and polyvinylidene fluoride with a ratio of 10; the volume ratio of the artificial graphite is 30%, and the mass ratio of the lithium titanate is 10%.

[0052] The preparation method of the negative electrode material is as follows:

[0053] SiO 2 Stir the mixed material of artificial stone mill, lithium titanate, carbon fiber, polyvinylidene fluoride at a mass ratio of 87:5:5:3, and water at a stirring line speed of 60m / min for 50min to obtain a mixture with a solid content of 55%. The slurry was dried at 60° C. for 8 hours to obtain the negative electrode material.

Embodiment 3

[0055] This embodiment provides an anode material, the anode material comprising SiO with a median particle size of 20 μm 2 The inner core of the natural graphite mixed material with a median particle size of 10 μm and a buffer layer coated on the surface of the inner core, the buffer layer comprising graphene with a median particle size of 5 μm and an aspect ratio of 15 and polyacrylate; the volume ratio of the natural graphite is 50%, and the mass ratio of the hard carbon is 5%.

[0056] The preparation method of the negative electrode material is as follows:

[0057] SiO 2 Stir with the mixed material of artificial stone mill, hard carbon, graphene, polyacrylate with the mass ratio of 93.3:5:0.5:1.2 and N-methylpyrrolidone at a stirring line speed of 80m / min for 30min, and obtain a solid content of 45 % of the mixed slurry was dried at 60° C. for 8 hours to obtain the negative electrode material.

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Abstract

The invention provides a negative electrode material and a preparation method and application thereof. The negative electrode material comprises an inner core containing a silicon-based material and a buffer layer coating the surface of the inner core, the buffer layer comprises a low-expansion material, a conductive agent and a binder, and the low-expansion material comprises any one or a combination of at least two of hard carbon, soft carbon, lithium titanate, natural graphite and artificial graphite. According to the negative electrode material provided by the invention, under the condition of cyclic charging and discharging, lithium ions are preferentially separated and embedded in the surface layer low-expansion material, so that overlarge expansion and overlarge volume change caused by overlarge lithium removal and lithium embedding degrees of material particles of a silicon-based material system, and the long-term performance deterioration caused by overlarge expansion and overlarge volume change are prevented; and under the condition that the energy density loss is relatively smaller, the cell expansion can be greatly improved, the long-term reliability of the battery is improved, and the cycle performance and the storage performance of the battery are improved.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and relates to a negative electrode material and a preparation method and application thereof. Background technique [0002] With the development of electric vehicles, the requirements for the energy density of power batteries (the current normal level is 180-230wh / kg) are getting higher and higher. As the core component of electric vehicles, the energy density of power batteries affects the design of the whole vehicle, including the performance of the whole vehicle and cost control, high-energy-density power batteries can effectively control the weight of the vehicle and the design of other components. In addition, power batteries account for nearly 50% of the cost of electric vehicles. Increasing the energy density of power batteries will reduce the cost of non-energy units such as mechanical parts. Cost, so as to effectively control the cost of the whole vehicle. [0003] At pre...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/48H01M4/587H01M4/62H01M10/0525
CPCH01M4/364H01M4/366H01M4/483H01M4/587H01M4/625H01M4/628H01M10/0525H01M2004/021H01M2004/027H01M2220/20Y02E60/10
Inventor 郭明奎苏树发高飞
Owner SVOLT ENERGY TECHNOLOGY CO LTD
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