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Preparation method for negative electrode material with core-shell coated structure and for lithium ion battery

A lithium-ion battery and coating structure technology, applied in the field of nanomaterials and new energy materials, can solve the problems of unsuppressed volume expansion, many graphene defects, and shedding of active materials, and achieves low cost, excellent mechanical properties, The effect of high conductivity

Inactive Publication Date: 2017-07-11
SOUTHEAST UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Among them, carbon-coated nano-silicon can improve its electrical conductivity and inhibit its volume change. However, due to the mechanical stress caused by the volume change of silicon, it will lead to cracking, and finally lead to the destruction of the structure, the decrease of electrical conductivity, and the active material falling off; Graphene oxide and nano-silicon powder are compounded and then thermally reduced. The resulting graphene and silicon are only mechanically combined, and there are many defects in graphene. After many cycles, silicon is easily detached from the graphene matrix, and the volume expands. Can not be suppressed, resulting in its capacity attenuation

Method used

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  • Preparation method for negative electrode material with core-shell coated structure and for lithium ion battery
  • Preparation method for negative electrode material with core-shell coated structure and for lithium ion battery
  • Preparation method for negative electrode material with core-shell coated structure and for lithium ion battery

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Experimental program
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Effect test

Embodiment 1

[0026] Take 160mL of absolute ethanol and 40mL of deionized water, weigh 200mg of nano-silicon powder and add it to the water-ethanol mixed solution, seal it and sonicate for 2h, add 2mL of concentrated ammonia water and 1mL of ethyl orthosilicate to the solution, and stir magnetically for 8-10h. Centrifuge three times, the cleaning solution is a mixture of ethanol and water with a volume ratio of 1:1, and then dry at a constant temperature at 80°C for 8 hours; take 400 mg of the sample and dissolve it in 160 mL of deionized water, add 193.8 mg of Tris buffer, ultrasonicate for 2 hours, add 400 mg of dopamine hydrochloride, and stir React for 24 hours, centrifuge three times with deionized water, dry at 80°C for 8 hours, and calcine the sample in an argon atmosphere to carbonize the organic matter on the surface, keep at 700°C for 2 hours, and the heating rate is 3°C / min, and wait for natural cooling ; The sample was ultrasonically dispersed in deionized water, then dropped int...

Embodiment 2

[0031] Add 150 mg of graphene oxide (GO) to 75 mL of deionized water to make 2 mg / mL, add 150 mg of carbon-coated silicon to 75 mL of deionized water to make 2 mg / mL, ultrasonically disperse for 2 hours, and mix the two solutions with magnetic stirring for 4 hours to disperse Suction filter after uniformity, take it out after about 1.5h, put the obtained film into the dryer for 12h to dry, and obtain the GO / Si@C composite material, heat the obtained product to 700°C in a vacuum heat treatment furnace, and keep it warm 120min, the air pressure is 50Pa. That is, the r-GO / Si@C composite material was obtained, and it was prepared as a lithium-ion battery anode material, and the first charge and discharge capacity was 630.5mAh g -1 and 1162.1mAh·g -1 , 553.8mAh·g after 100 cycles -1 and 560.5mAh·g -1 , the initial capacity is low, but the cycle stability is better, and the capacity retention rate reaches 87.8%.

Embodiment 3

[0033] Add 200mg of graphene oxide (GO) to 100mL deionized water to make 2mg / mL, add 100mg of carbon-coated silicon to 50mL deionized water to make 2mg / mL, and ultrasonically disperse for 2 hours. Stir the two solutions for 6 hours to disperse evenly Suction filtration in a vacuum water pump, take it out after about 2.5h, put the obtained film into a dryer for 12h drying treatment, and obtain a GO / Si@C composite material, heat the obtained product to 700°C in a vacuum heat treatment furnace , keep warm for 120min, and the air pressure is 50Pa. That is, the r-GO / Si@C composite material was obtained, and it was prepared as a negative electrode material for lithium-ion batteries. The first charge and discharge capacities were 259.5mAh g -1 and 734.3mAh·g -1 , 289.5mAh·g after 100 cycles -1 and 291.5mAh·g -1 , although the capacity is too low, but the cycle stability is very good, almost no loss of capacity.

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Abstract

The invention discloses a preparation method for a negative electrode material with a core-shell coated structure and for a lithium ion battery. The preparation method is simple in process and easy to control. The preparation method comprises the following steps: preparing a graphene oxide material; then preparing a core-shell-structured carbon-coated silicon material from nanometer silicon; blending graphene oxide with carbon-coated silicon powder according to a certain ratio; after uniform blending, carrying out pumping filtration so as to obtain a two-dimensional film; and then carrying out thermal reduction so as to obtain the core-shell-structured carbon-coated silicon / graphene composite material. The electrode material prepared by using the method has initial charge and discharge capacities of 835.8 mAh / g and 1452.3 mAh / g respectively when current density is 200 mA / g and has charge and discharge capacities of 705.1 mAh / g and 710.9 mAh / g respectively after 100 cycles, so the electrode material has a capacity retention rate of 84.4% and good cycle stability.

Description

technical field [0001] The invention relates to a preparation method of a lithium-ion battery negative electrode core-shell coating structure material, which belongs to the field of nanometer materials and new energy materials. Background technique [0002] Lithium-ion batteries have become the most widely used secondary batteries due to their outstanding advantages such as high working voltage, high energy density, long cycle life, small self-discharge, and no memory effect. Anode materials are an important part of lithium-ion batteries. Silicon anode material has the highest theoretical specific capacity (~4200mAh / g), low charge and discharge potential, and abundant reserves. It is considered to be the most promising to replace traditional graphite anode materials and become the next generation of new high-capacity lithium-ion battery anode materials. However, during the charging and discharging process, the silicon material has a huge volume change (~300%), which leads t...

Claims

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Application Information

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IPC IPC(8): H01M4/36H01M4/38H01M4/583H01M10/0525
CPCH01M4/366H01M4/386H01M4/583H01M10/0525Y02E60/10
Inventor 陈坚沈园方王丹徐晖
Owner SOUTHEAST UNIV
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