Multilayer nano-composite electrode for lithium ion battery and preparation method thereof

A lithium-ion battery and nanocomposite technology, which is applied in battery electrodes, nanotechnology for materials and surface science, nanotechnology, etc. problem, to achieve the effect of reducing irreversible capacity, increasing energy density, and reducing shedding

Pending Publication Date: 2017-04-26

SOUTH CHINA UNIV OF TECH

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Problems solved by technology

Graphite is currently used as the negative electrode active material for lithium-ion batteries. However, the theoretical specific capacity of graphite is not high enough to meet the growing energy demand.

As an active material, silicon has a high theoretical specific capacity, but the volume expansion is greater than 300%, which will cause the active material to pulverize and fall off, increase the irreversible capacity, and shorten the battery life

Many researchers use carbon-silicon core-shell nanostructures as the active material, which can well limit the...

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Method used

Described lithium ion half battery is in charging and discharging process, because copper current collector has copper nanoneedle, combines with the active material of nano material, has strengthened the conductivity of active material; Active material on the multilayer nanocomposite electrode It is a silicon-carbon composite nano-layer, which greatly reduces the pulverization of the active material caused by the lithium ion intercalation and detachment of the active material during the charging and discharging process, and also shortens the distance for the lithium ion to enter the active material, increasing the battery life. Lithium-ion battery life and charge-discharge rate; at the same time, the active material of the novel multilayer nano-composite electrode does not contain binder and other materials, which reduces the resistance of the act...

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Abstract

The invention discloses a multilayer nano-composite electrode for a lithium ion battery and preparation method thereof. The multilayer nano-composite electrode is mainly composed of a copper current collector and multilayer active substances; the copper current collector is provided with a porous structure and a nano-needle structure; the multilayer active substances comprise a silicon layer and a carbon layer. The preparation method of the multilayer nano-composite electrode is as follows: (1) sintering of copper powder; (2) growing and reducing of copper oxide nanoneedle structure; (3) depositing of a silicon nanometer layer; and (4) cladding of the carbon nanometer layer. The multilayer nano-composite electrode disclosed by the invention can effectively limit the sharp change of the volume of silicon active substance in the charging/discharging process of the battery, thereby prolonging the cycle life of the battery; and meanwhile, the porous structure and the nano-needle structure of the current collector are directly and tightly contacted with the active substances, the use of each of the adhesive and the conductive additive is reduced, thereby facilitating the improvement of the reversible capacity, the coulombic efficiency, the cycle stability and other electrochemical properties of the battery.

Application Domain

Material nanotechnologyElectrode carriers/collectors +1

Technology Topic

Current collectorLithium electrode +11

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Examples

Experimental program(2)

Example Embodiment

[0037] Example 1

[0038] The preparation of a novel multilayer nanocomposite electrode for lithium ion batteries includes the following steps:

[0039] (1) Copper powder sintering: Weigh the copper powder and place it in a customized graphite mold, then place it in a vacuum resistance furnace and sinter it at a high temperature in a hydrogen environment. The sintering temperature is 900°C and the holding time is 2h;

[0040] (2) The growth of copper oxide nanoneedles: place the sintered sample in a muffle furnace and heat it at high temperature in the air at a heating temperature of 500°C and a holding time of 7 hours to obtain copper oxide with nanoneedles grown;

[0041] (3) Reduction of copper oxide nano-needles: Place the copper oxide with nano-needles in a vacuum resistance furnace, and reduce the copper oxide nano-needles in a hydrogen environment with a heating temperature of 250°C and a holding time of 2 hours to obtain a copper current collector ;

[0042] (4) Deposition of silicon nano-layer: Put the copper current collector into the CVD reactor, and pass 5ml of pure silane (SiH4) per minute. The reaction pressure is 75Pa, the temperature is 200℃, the time is 30min, and the RF power is 75mW. /cm 2 , Complete the deposition of silicon nano-layer;

[0043] (5) Coating of the carbon nano layer: The obtained sample is soaked in a polyvinyl alcohol solution with a mass fraction of 5% for 3 hours, and then dried in a vacuum for 7 hours at a drying temperature of 60°C; the dried sample is placed in a vacuum In the resistance furnace, heat preservation in an argon atmosphere, the heating temperature is 250℃, and the heat preservation time is 3h.

[0044] The structure diagram of the prepared multilayer nanocomposite electrode and the microstructure diagram of the monomer particles are as follows: figure 1 with figure 2 As shown, the multilayer nanocomposite electrode is mainly composed of a copper current collector and a multilayer active material; including copper nano-needle structures 9, copper powder particles 10, silicon nano-layers 11 and carbon nano-layers 12;

[0045] The copper current collector is composed of copper powder particles 10; the copper current collector has a porous structure and a nano-needle structure 9; the porous structure exists between the copper powder particles 10; the nano-needle structure 9 is in the copper powder On the surface of the particle 10; the multilayer active material is coated on the outer surface of the copper powder particle 10 with a nano-needle structure; the multilayer active material includes a silicon nano layer 11 and a carbon nano layer 12, the carbon nano The layer 12 covers the outer surface of the silicon nano layer 11.

Example Embodiment

[0046] Example 2

[0047] The multilayer nanocomposite electrode prepared in Example 1 is used to assemble a lithium-ion half-cell, and the assembly diagram is as follows image 3 As shown, it includes an upper battery shell 1, an elastic sheet 2, a gasket 3, a lithium sheet 4, a diaphragm 5, an electrolyte 6, a lower battery shell 7 and a novel multilayer nanocomposite electrode 8;

[0048] The multilayer nano composite electrode 8 is placed on the lower battery shell 7. The electrolyte 6 directly infiltrates the active material of the needle-shaped nano composite layer on the multilayer nano composite electrode 8, and the electrolyte 6 is filled with the multilayer nano composite electrode 8. The entire cavity formed by the shell 7 and the diaphragm 5; the lithium sheet 4 is tightly attached to the diaphragm 5, and the upper surface of the lithium sheet 4 is placed on the upper surface of the lithium sheet 4 sequentially from the bottom to the top with the gasket 3 and the elastic sheet 2, and the gasket 3 and the elastic sheet 2 are adjusted The effect of pressure; the shrapnel 2 is in close contact with the upper battery shell 1 to reduce contact resistance and ensure good electrical conductivity inside the battery.

[0049] After the lithium-ion half-cell is assembled, when the lithium-ion half-cell is discharged, the lithium sheet 4 begins to delithium, and the lithium ions enter the electrolyte 6 through the diaphragm 5, and then interact with the needle-like nanocomposite layer on the multilayer nanocomposite electrode 8. When the active material comes into contact, a lithium insertion reaction occurs; at the same time, electrons enter the lower battery case 7 through the gasket 3, the shrapnel 2 and the upper battery case 1. Since the lower battery case 7 is in close contact with the new multilayer nanocomposite electrode 8, Therefore, the electrons then enter the active material of the needle-shaped nanocomposite layer of the novel multilayer nanocomposite electrode 8 to neutralize the lithium ions and complete the discharge process of the lithium ion half-cell.

[0050] When the lithium ion half-cell is charged, lithium ions are first extracted from the active material of the needle-shaped nanocomposite layer on the novel multilayer nanocomposite electrode 8, enter the electrolyte 6, and then contact the lithium sheet 4 through the diaphragm 5; The active material transferred from the new multilayer nanocomposite electrode 8 passes through the lower battery case 7, the upper battery case 1, the shrapnel 2, the gasket 3, and the lithium ions on the lithium sheet 4 for charge balance to complete the charging process.

[0051] During the charging and discharging process of the lithium ion half-cell, because the copper current collector has copper nano-needles, it is combined with the active material of the nano material to enhance the conductivity of the active material; the active material on the multilayer nano composite electrode is silicon carbon The composite nano layer greatly reduces the pulverization of the active material caused by the insertion and separation of lithium ions from the active material during the charging and discharging process of the battery, and also shortens the path of lithium ions into the active material, increasing the size of the lithium ion battery Life span and charge-discharge rate; meanwhile, the active material of the novel multilayer nanocomposite electrode does not contain binders and other materials, which reduces the resistance of the active material and improves the energy density of the lithium ion battery.

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Classification and recommendation of technical efficacy words

Improve charge and discharge performance
Improve electrical conductivity

Non-aqueous electrolyte containing fluorine-substituted succinic anhydride and succinic anhydride derivatives, and alkali metal secondary battery comprising thereof

InactiveCN102324562AImprove charge and discharge performanceGood life cycleSecondary cellsSolventCharge and discharge

Owner:SHANGHAI INST OF SPACE POWER SOURCES

Multilayer nano-composite electrode for lithium ion battery and preparation method thereof

A lithium-ion battery and nanocomposite technology, which is applied in battery electrodes, nanotechnology for materials and surface science, nanotechnology, etc. problem, to achieve the effect of reducing irreversible capacity, increasing energy density, and reducing shedding

AI-Extracted Technical Summary

Problems solved by technology

Method used

Abstract

Image

Examples

Example Embodiment

Example Embodiment

PUM

Description & Claims & Application Information

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