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Silicon graphene core-shell material with gaps and preparation and application of silicon graphene core-shell material

A graphene, graphene layer technology, applied in nanotechnology for materials and surface science, electrical components, electrochemical generators, etc., can solve problems such as insufficient stability and decreased cycle performance

Inactive Publication Date: 2016-01-06
王晓亮
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, better solutions are still needed for the degradation of cycle performance and insufficient stability of silicon materials due to volume changes during cycle charge and discharge.

Method used

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  • Silicon graphene core-shell material with gaps and preparation and application of silicon graphene core-shell material
  • Silicon graphene core-shell material with gaps and preparation and application of silicon graphene core-shell material
  • Silicon graphene core-shell material with gaps and preparation and application of silicon graphene core-shell material

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0084] Preparation of silicon graphene core-shell material, the process is as follows figure 1 .

[0085]1 gram of silicon particle raw material with a diameter of about 100 nanometers is placed in a muffle furnace, the atmosphere is atmospheric, the pressure is 15 psi, and the flow rate is 70 sccm. The heating rate is 20°C / min, the holding temperature is 950°C, and the holding time is 1 minute. After the holding is over, it is naturally cooled to form a sacrificial template on the surface of the silicon particles.

[0086] Place the obtained silicon particles with a sacrificial template in a tube furnace, the heating atmosphere is argon, the pressure is 12.5 psi, the flow rate is 50 sccm, the heating rate is 100 degrees per minute, the holding temperature is 900 degrees, and the holding time is 5 minutes , the heat preservation atmosphere is methane, the pressure is 12.5psi, the flow rate is 100sccm, and then cooled with the furnace, the cooling atmosphere is argon, the pres...

Embodiment 2

[0092] Preparation of silicon material C2

[0093] Same as Example 1, the difference lies in: the holding temperature for forming the sacrificial template is 1100°C.

Embodiment 3

[0095] Preparation of silicon material C3

[0096] Same as Example 1, the difference is that the particle size of the silicon particle raw material is 40nm.

[0097] The materials obtained in Examples 1-3 and Comparative Example 1 were tested by XRD, thermogravimetric, SEM and TEM.

[0098] figure 2 is the XRD pattern of silicon material 1. From figure 2 It can be seen that the silicon material 1 has a high degree of crystallinity, which is 95%, and the main peaks are at 28.44° (111 plane), 47.31° (220 plane), 56.13° (311 plane), 69.14° (400 plane), 76.38° (331 plane), 88.04° (422 plane), basically no other impurity peaks appear. It can be seen that the preparation process of the silicon material 1 does not change the crystal structure of the silicon particle raw material.

[0099] image 3 It is the SEM picture of silicon material 1. It can be seen that the silicon material has a silicon core with a diameter of 100 nm. Outside the silicon core there is a graphene sh...

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Abstract

The invention provides a silicon graphene core-shell material with gaps. The silicon graphene core-shell material is a material with a core-shell structure; an inner core is made of silicon particles; a housing is made of graphene; and gaps with the distances of 0.1nm to 10 microns are formed between the inner core and the housing. The invention further provides a preparation method of the silicon graphene core-shell material and an application of the material as a lithium-ion battery anode material. The first lithium deintercalation capacity of the lithium-ion battery employing the silicon material provided by the invention as a negative active material can be up to 3015mA.h / g; the lithium-ion battery prepared from the silicon material as the negative active material has a high rate capability; and the lithium deintercalation capacity at the rate of 5C can be up to 2440mA.h / g. According to the core-shell gap structure of the silicon material provided by the invention, volume expansion and contraction and mechanical stress caused by the volume expansion and contraction in charging and discharging process of the lithium-ion battery can be effectively accommodated and alleviated; the volume effect is removed; and the prepared lithium-ion battery has excellent cycling stability.

Description

technical field [0001] The invention belongs to the field of energy materials, and in particular relates to an electrode material with a graphene coating layer and a preparation method thereof. Background technique [0002] Graphite material is the main negative electrode material used in lithium-ion batteries, and its theoretical capacity is 372mAh / g. At present, the battery is close to the limit of its energy density. With the continuous improvement of market requirements for battery energy density, it is an inevitable trend to replace graphite materials with high-capacity negative electrodes (such as silicon, germanium and tin, with theoretical capacities of 4200mAh / g, 1600mAh / g and 994mAh / g, respectively). [0003] However, the above-mentioned high-capacity negative electrode materials have not been really applied to lithium-ion batteries due to the following shortcomings: (1) charging and discharging are accompanied by large volume changes, resulting in particle pulveri...

Claims

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Application Information

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IPC IPC(8): H01M4/36H01M4/38H01M10/0525B82Y30/00
CPCB82Y30/00H01M4/366H01M4/386H01M10/0525H01M2004/021Y02E60/10
Inventor 王晓亮
Owner 王晓亮
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