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Micron silicon composite material and preparation method and application thereof

A silicon composite material and coating technology, which is applied in structural parts, electrical components, battery electrodes, etc., can solve the problems of poor performance, unreasonable preparation process of micro-silicon composite materials, and high cost of nano-scale production, so as to improve the electrical conductivity. efficiency, good isolation effect, and the effect of improving cycle stability

Active Publication Date: 2022-04-01
BEIJING WELION NEW ENERGY TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0007] In view of the above-mentioned problems such as the high cost of nano-production and the unreasonable preparation process of the micro-silicon composite material leading to poor performance, the present invention proposes a micro-silicon composite material and its preparation method and application; its structure and preparation method overcome the background Deficiencies and flaws mentioned in the technology

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  • Micron silicon composite material and preparation method and application thereof
  • Micron silicon composite material and preparation method and application thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0062] A micro-silicon composite material, which is a core-shell structure, and the core-shell structure is sequentially composed of micro-silicon, a first cladding layer 5, a cavity layer 2, a second cladding layer 4 and a third cladding layer from the inside to the outside 3.

[0063] Both the first coating layer 5 and the second coating layer 4 are carbon coating layers, the third coating layer 3 is a dense carbon coating layer, and the cavity layer 2 contains a conductive agent 1 .

[0064] The cavity layer reserves space for volume expansion for silicon intercalation of lithium, avoids the cracking of the carbon coating layer due to volume expansion of lithium during silicon intercalation, and maintains the integrity of the composite material. The first cladding layer provides good electrical conductivity and insulation effect for the composite material. The conductive agent maintains the close connection between the micron silicon and the second and third carbon coating...

Embodiment 2

[0072] A method for preparing a micron-silicon composite material, comprising the steps of:

[0073] (1) Carbon-coat micron-silicon by using a solid-phase method or a liquid-phase method to obtain sample 1 comprising the first coating layer and micron-silicon.

[0074] When the solid-phase method is adopted, the carbon coating layer is formed by uniformly mixing micron silicon and solid carbon source materials; the solid carbon source includes any one or a combination of pitch and phenolic resin.

[0075] When the liquid-phase method is adopted, the micro-silicon is added to the solvent, and the liquid-phase coating material is added for in-situ polymerization, separated and dried. The liquid phase coating material includes polyphenolic resin, polydopamine, tannic acid, PVA any one or a combination of at least two, and the mass ratio of the liquid phase coating material to micron silicon is (0.02~0.2):1 , such as 0.02:1, 0.1:1, 0.2:1, etc. The solvent is water or a mixed sol...

Embodiment 3

[0088] A lithium battery negative electrode, comprising a negative electrode slurry, the negative electrode slurry is made by dissolving a negative electrode active material, a conductive agent and a binder in deionized water, and the negative electrode active material is as described in Example 1 or Example 2 The micro-silicon composite material or the mixed material of the micro-silicon composite material and carbon, the negative electrode slurry is coated on the copper foil, and the negative electrode is obtained after drying; the solid content of the slurry is 5%.

[0089] Experimental group 1

[0090] A method for preparing a micro-silicon composite material, comprising the following steps:

[0091] S1. Take 20g of micro-silicon with a particle size of 2μm and add it to 200ml of buffer solution with a pH value of 8-9. After stirring evenly, add 1g of dopamine. After stirring for a period of time, separate and dry to form a polydopamine coating layer to obtain sample 1.

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Abstract

The invention provides a micron silicon composite material as well as a preparation method and application thereof, and belongs to the technical field of lithium ion batteries. The micron silicon composite material is of a core-shell structure and sequentially comprises micron silicon, a first coating layer, a cavity layer, a second coating layer and a third coating layer from inside to outside, the first coating layer and the second coating layer are carbon coating layers, the third coating layer is a compact carbon coating layer, a cavity layer is arranged between the second coating layer and the third coating layer, and a conductive agent is contained in the cavity layer. According to the micron silicon composite material, a volume expansion space is reserved for embedding lithium into silicon, so that the carbon coating layer is prevented from being broken due to the volume expansion of lithium when the silicon is embedded, the integrity of the composite material is maintained, and the cycling stability of the micron silicon composite material is improved. The invention further discloses a preparation method and application of the composite material, the preparation method is simple and easy to implement, and the prepared negative electrode is good in electrochemical performance.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a micro-silicon composite material and its preparation method and application. [0002] technical background [0003] As the anode material of a new generation of lithium-ion batteries, silicon has abundant reserves and the highest specific capacity among all alloyed lithium storage elements, so it has great potential to replace graphite as a commercial anode material. However, silicon has a 300% expansion defect when intercalating lithium. Seriously affected the cycle performance in actual use. [0004] At present, most technical solutions use nanotechnology to solve the problem of silicon expansion and cracking, including the use of nano-silicon as the active material to construct electrode materials and nano-design of carbon structures. For example, patent CN111816852A discloses a silicon-based composite negative electrode material. The conductive nano-silicon-ba...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/62H01M4/38H01M4/134H01M10/0525
CPCY02E60/10
Inventor 王胜彬王世贤
Owner BEIJING WELION NEW ENERGY TECH CO LTD
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