Silicon-carbon composite material as well as preparation method and application thereof

Abstract

The invention discloses a silicon-carbon composite material as well as a preparation method and application thereof. The silicon-carbon composite material comprises nanometer silicon, graphite and lithium carbonate. The nanometer silicon, graphite and lithium carbonate are encapsulated by polymers and carbonized so as to obtain the silicon-carbon composite material. The preparation method comprises the following steps: mixing graphite, lithium carbonate and nanometer silicon so as to obtain a lithium carbonate / silicon / graphite mixture; dispersing the lithium carbonate / silicon / graphite mixture into a polymer solution, and drying to obtain a precursor material; carbonizing the precursor material, thereby obtaining the silicon-carbon composite material. The silicon-carbon composite material disclosed by the invention has high electrical conductivity and excellent cycling stability and can be applied to preparing lithium ion batteries.

Description

technical field

[0001] The invention relates to the technical field of batteries, in particular to a silicon-carbon composite material and a preparation method and application thereof. Background technique

[0002] As an environmentally friendly chemical energy source, lithium-ion batteries have the advantages of small size, high energy density, and long cycle life, and are considered to be a very promising energy storage direction. At present, lithium-ion batteries have been widely used in the 3C field, and are also increasingly used in the HEV and EV fields. At the same time, with the rapid development of communication technology and the vigorous promotion of EV by governments of various countries, the requirements for energy density, power density and cycle life of lithium-ion batteries are also getting higher and higher. Compared with the more mature research on cathode materials, traditional carbon anode materials have become a constraint factor limiting battery capaci...

Examples

Embodiment 1

[0040] A kind of silicon-carbon composite material of the present invention, its preparation method comprises the following steps:

[0041] S1. Preparation of Si@G material:

[0042] 1.1. Weigh 0.6g of nano-silicon and 0.1g of dispersant CTAB, disperse in 50ml of ethanol and sonicate for half an hour to obtain nano-silicon dispersion;

[0043] 1.2, weigh 0.3g lithium carbonate and 3g flake graphite, add in 60ml of ethanol and stir for 2h to obtain lithium carbonate / graphite dispersion;

[0044] 1.3. Add the nano-silicon dispersion liquid in step 1.1 dropwise into the lithium carbonate / graphite dispersion liquid dispersion liquid in step 1.2, stir for 2 hours and then ultrasonically treat for 40 minutes, (the working frequency of the ultrasonic cell disruptor is 22±1kHz) to obtain a uniform dispersion liquid;

[0045] 1.4. Vacuum filter the uniform dispersion in step 1.3 to obtain the filter residue, and dry the filter residue in a vacuum drying oven at 80°C;

[0046] 1.5. Put ...

Embodiment 2

[0056] A kind of silicon-carbon composite material of the present invention, its preparation method comprises the following steps:

[0057] S1, preparation of silicon-graphite lithium carbonate mixed solution:

[0058] 1.1. Weigh 0.6g of nano-silicon and disperse it in 50ml of deionized water to obtain a nano-silicon dispersion;

[0059] 1.2, Weigh 0.3g lithium carbonate and 3g flake graphite, add 100ml of deionized water to disperse to obtain lithium carbonate / graphite dispersion;

[0060] 1.3. Add the nano-silicon dispersion liquid in step 1.1 dropwise into the lithium carbonate / graphite dispersion liquid in step 1.2, and ball mill at a speed of 350 r / min for 1 h to obtain a lithium carbonate / silicon / graphite mixture.

[0061] S2. Preparation of precursor materials:

[0062] 2.1. Dissolve 1.5g glucose in 250ml deionized water to obtain glucose solution;

[0063] 2.2. Add the lithium carbonate / silicon / graphite mixture in step S1 dropwise to the glucose solution in step 2.1...

Embodiment 3

[0070] A kind of silicon-carbon composite material of the present invention, its preparation method comprises the following steps:

[0071] S1, preparation of silicon-graphite lithium carbonate mixed solution:

[0072] 1.1. Weigh 0.6g of nano-silicon and 3g of graphite flakes and mix them, and disperse them in 100ml of ethanol to obtain a silicon / graphite mixture;

[0073] 1.2, weigh 0.2g lithium carbonate and 0.1g agar, add 80ml of deionized water to obtain agar / lithium carbonate mixed solution;

[0074] 1.3. Add the agar / lithium carbonate mixture in step 1.2 into the silicon / graphite mixture in step 1.1, stir continuously, and sonicate for 2 hours (the working frequency of the ultrasonic cell disruptor is 22±1kHz) to obtain the lithium carbonate / silicon / graphite mixture liquid;

[0075] 1.4. Stir the lithium carbonate / silicon / graphite mixture in an oil bath at 80°C and evaporate to dryness, put the evaporated dry matter into a ball mill jar, under an argon atmosphere, with...

technical field

[0001] The invention relates to the technical field of batteries, in particular to a silicon-carbon composite material and a preparation method and application thereof. Background technique

[0002] As an environmentally friendly chemical energy source, lithium-ion batteries have the advantages of small size, high energy density, and long cycle life, and are considered to be a very promising energy storage direction. At present, lithium-ion batteries have been widely used in the 3C field, and are also increasingly used in the HEV and EV fields. At the same time, with the rapid development of communication technology and the vigorous promotion of EV by governments of various countries, the requirements for energy density, power density and cycle life of lithium-ion batteries are also getting higher and higher. Compared with the more mature research on cathode materials, traditional carbon anode materials have become a constraint factor limiting battery capaci...

Examples

Embodiment 1

[0040] A kind of silicon-carbon composite material of the present invention, its preparation method comprises the following steps:

[0041] S1. Preparation of Si@G material:

[0042] 1.1. Weigh 0.6g of nano-silicon and 0.1g of dispersant CTAB, disperse in 50ml of ethanol and sonicate for half an hour to obtain nano-silicon dispersion;

[0043] 1.2, weigh 0.3g lithium carbonate and 3g flake graphite, add in 60ml of ethanol and stir for 2h to obtain lithium carbonate / graphite dispersion;

[0044] 1.3. Add the nano-silicon dispersion liquid in step 1.1 dropwise into the lithium carbonate / graphite dispersion liquid dispersion liquid in step 1.2, stir for 2 hours and then ultrasonically treat for 40 minutes, (the working frequency of the ultrasonic cell disruptor is 22±1kHz) to obtain a uniform dispersion liquid;

[0045] 1.4. Vacuum filter the uniform dispersion in step 1.3 to obtain the filter residue, and dry the filter residue in a vacuum drying oven at 80°C;

[0046] 1.5. Put ...

Embodiment 2

[0056] A kind of silicon-carbon composite material of the present invention, its preparation method comprises the following steps:

[0057] S1, preparation of silicon-graphite lithium carbonate mixed solution:

[0058] 1.1. Weigh 0.6g of nano-silicon and disperse it in 50ml of deionized water to obtain a nano-silicon dispersion;

[0059] 1.2, Weigh 0.3g lithium carbonate and 3g flake graphite, add 100ml of deionized water to disperse to obtain lithium carbonate / graphite dispersion;

[0060] 1.3. Add the nano-silicon dispersion liquid in step 1.1 dropwise into the lithium carbonate / graphite dispersion liquid in step 1.2, and ball mill at a speed of 350 r / min for 1 h to obtain a lithium carbonate / silicon / graphite mixture.

[0061] S2. Preparation of precursor materials:

[0062] 2.1. Dissolve 1.5g glucose in 250ml deionized water to obtain glucose solution;

[0063] 2.2. Add the lithium carbonate / silicon / graphite mixture in step S1 dropwise to the glucose solution in step 2.1...

Embodiment 3

[0070] A kind of silicon-carbon composite material of the present invention, its preparation method comprises the following steps:

[0071] S1, preparation of silicon-graphite lithium carbonate mixed solution:

[0072] 1.1. Weigh 0.6g of nano-silicon and 3g of graphite flakes and mix them, and disperse them in 100ml of ethanol to obtain a silicon / graphite mixture;

[0073] 1.2, weigh 0.2g lithium carbonate and 0.1g agar, add 80ml of deionized water to obtain agar / lithium carbonate mixed solution;

[0074] 1.3. Add the agar / lithium carbonate mixture in step 1.2 into the silicon / graphite mixture in step 1.1, stir continuously, and sonicate for 2 hours (the working frequency of the ultrasonic cell disruptor is 22±1kHz) to obtain the lithium carbonate / silicon / graphite mixture liquid;

[0075] 1.4. Stir the lithium carbonate / silicon / graphite mixture in an oil bath at 80°C and evaporate to dryness, put the evaporated dry matter into a ball mill jar, under an argon atmosphere, with...

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