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Method for preparing hollow core-shell structure nano silicon-carbon composite material by taking polyaniline as carbon source and secondary battery applying material

A composite material and core-shell structure technology, which is applied in the field of lithium-ion batteries, can solve problems such as barriers to realization, current collector surface shedding conductivity, SEI film damage, etc., to achieve specific capacity improvement, stable capacity performance, and avoid pulverization failure Effect

Inactive Publication Date: 2020-05-12
BEIJING UNIV OF CHEM TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] However, silicon anode materials have encountered various development bottlenecks due to their large volume expansion (~300%) during the charge and discharge process, resulting in particle pulverization, damage to the SEI film, shedding on the surface of the current collector, and poor conductivity.
Common solutions to these problems such as (1) designing silicon anode materials such as nanoparticles, nanosheets, nanowires or porous morphology; (2) coating silicon materials; (3) designing amorphous silicon electrodes, etc., however The realization of these methods has more or less encountered obstacles

Method used

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  • Method for preparing hollow core-shell structure nano silicon-carbon composite material by taking polyaniline as carbon source and secondary battery applying material
  • Method for preparing hollow core-shell structure nano silicon-carbon composite material by taking polyaniline as carbon source and secondary battery applying material
  • Method for preparing hollow core-shell structure nano silicon-carbon composite material by taking polyaniline as carbon source and secondary battery applying material

Examples

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Effect test

Embodiment example 1

[0030] According to the characteristics of the template etching method, it is preferable to use tetraethyl orthosilicate as the silicon source for preparing the silica template layer. Weigh tetraethyl orthosilicate and nano-silicon particles according to the mass ratio of 10:1, first disperse the silicon nanoparticles in the solution prepared by ethanol and water according to the volume ratio of 4:1 and stir them evenly with a magnetic stirrer, and ultrasonically Disperse for 30 minutes. Then add a certain amount of concentrated ammonia water dropwise into the system, and magnetically stir evenly. Finally, add the previously weighed tetraethyl orthosilicate dropwise to the mixing system, and continue the magnetic stirring reaction at room temperature for more than 10 hours. After fully reacting, high-speed centrifugation separates the silicon nanoparticles coated with the silica template layer. , and centrifuged three times with ethanol. The resulting product was fully dried...

Embodiment example 2

[0033] The carbon-coated nano-silicon composite with hollow core-shell structure prepared in Case 1 was used for secondary lithium-ion batteries. Adopt composite material: acetylene black: CMC=7: 1.5: 1.5 mass ratio to coat the pole piece, as the positive pole of the half battery, use metal lithium as the negative pole, assemble the 32 button half battery, carry out the charge and discharge test with the blue battery, in At a constant temperature of 25°C, a constant current charge and discharge test was performed with a current of C / 20. Figure 4 The charge-discharge curves of the first three cycles of the half-cell are given. Figure 5 The half-cell rate performance test scatter diagram is given. It can be seen that the specific capacity of the composite material has reached 700mAh / g, effectively utilizing the high-capacity performance of silicon, and at the same time, due to the protection of the carbon-coated hollow core-shell structure, it can also exert relatively good c...

Embodiment example 3

[0035] An AC impedance test was performed on the assembled half-cells in Case 2. Using EIS AC impedance spectroscopy for testing. The frequency range is 0.1Hz ~ 1MHz, and the test temperature is room temperature. A comparative impedance test was also carried out on the half-cell mounted on the pole piece coated with pure silicon nanoparticles. Spectrum such as Figure 6 As shown, it can be seen that the as-prepared composite material has lower electrical resistance and higher ionic conductivity compared with pure silicon nanoparticles, which also confirms the effectiveness of the composite with carbon materials.

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Abstract

The invention relates to preparation of a hollow core-shell structure nano silicon-carbon composite material and an application of the composite material to a lithium ion secondary battery. The methodcan be used for commercialized negative electrode materials of lithium ion batteries. The composite material effectively alleviates the particle pulverization problem caused by volume expansion of silicon particles in the charging and discharging process, improves the electrode conductivity and obtains a stable SEI film, so the high reversible specific capacity and stable cycle performance of thesilicon material applied to the lithium ion battery negative electrode are realized. The preparation process of the lithium ion battery can be simplified, the cost is reduced, and the capacity and the energy density of the battery can be remarkably improved.

Description

technical field [0001] The invention relates to the preparation of a carbon-coated nano-silicon composite material with a hollow core-shell structure and a lithium ion battery using the silicon-carbon composite material. Background technique [0002] The success of lithium-ion batteries has benefited from the replacement of metallic lithium anodes with lithium intercalation compounds. An ideal negative electrode material should have the following conditions: good cycle life and charge-discharge reversibility; small irreversible capacity for the first time; good compatibility with electrolyte solvent; high discharge specific capacity; material safety, environmental protection No pollution; rich material resources, low prices, etc. The currently developed negative electrode materials are difficult to meet the above requirements at the same time. Therefore, the development and research of new negative electrode materials with better electrochemical performance has become the ...

Claims

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Application Information

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IPC IPC(8): H01M4/36H01M4/38H01M4/62H01M10/0525B82Y30/00
CPCB82Y30/00H01M4/366H01M4/386H01M4/625H01M4/628H01M10/0525H01M2004/021H01M2004/027Y02E60/10
Inventor 孔卫康卢侠王帅刚
Owner BEIJING UNIV OF CHEM TECH
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