A silicon-based composite negative electrode material for lithium-ion batteries and its preparation method

Abstract

The invention discloses a silicon-based composite anode material for a lithium ion battery and a preparation method thereof. The anode material comprises a graphite skeleton and an amorphous carbon layer which coats the graphite skeleton. The graphite skeleton is filled with a silicon material coated with a carbon-containing structure. The silicon material and the graphite skeleton are combined through a loose carbon material. The preparation method at least comprises the following steps: (1) preparing the silicon material coated with the carbon-containing structure; (2) preparing spherical particles with graphite as the main body; (3) coating the spherical particles with the amorphous carbon layer; and (4) granulating. According to the invention, the electric insulation problem of silicon anode due to its volume change can be solved, and it can be guaranteed that silicon active component can always be electrically contacted with a current collector during the charge-discharge cycle process. Meanwhile, huge stress effect caused by volume expansion / shrinkage of the active material silicon is further buffered. Then, the composite material has characteristics of high electrochemical cycle stability and regulable specific capacity.

Description

technical field

[0001] The invention relates to a silicon-based composite negative electrode material for lithium-ion batteries and a preparation method thereof, belonging to the technical field of lithium-ion batteries. Background technique

[0002] Due to its performance advantages, lithium-ion batteries have been used in various mobile energy storage, such as laptops, mobile phones and cameras. With the development of lithium-ion batteries, lithium-ion batteries with high specific energy, long life and low cost that can be applied to electric vehicles and large-scale energy storage power stations will become the focus of research. At present, the development and progress of cathode materials, one of the main factors determining battery performance, has laid the foundation for the research and development of high-performance lithium-ion batteries; however, graphite-based commercial anode materials are limited by their specific capacity (theoretical specific capacity is 372...

Examples

Embodiment 1

[0040] Get 23g silicon nanoparticles (particle size D50 is 100nm), 10g glucose and 2.5g S-p are dispersed in the mixed solvent of 700g water and 100g ethanol, through ultrafine ball milling 1h, then through spray drying, obtain granular powder, the granular powder The powder was calcined at 200° C. for 0.5 h in a tube vacuum furnace under argon protection to obtain material A.

[0041] The above-mentioned material A, 5g polyacrylic acid, 0.25g carbon fiber and 172.5g Ks-6 were dispersed in a mixed solvent of 700g water and 100g ethanol, ball milled for 2h, and then spray-dried to obtain a granular powder. Material B was obtained by calcining at 300° C. for 0.5 h in a vacuum furnace under the protection of argon.

[0042] Take 15g of the above-mentioned material B and 5g of medium-temperature pitch and disperse in 25g of toluene, stir and mix to obtain a paste mixture C, put the paste C into a vacuum tube furnace, protect it with argon, and calcinate at 1050°C for 90min to obta...

Embodiment 2

[0046] Get 23g silicon nanoparticles (particle diameter D50 is 500nm), 10g glucose and 2.5g S-p are dispersed in the mixed solvent of 500g water and 100g ethanol, through ultrafine ball milling 3h, then through spray drying, obtain granular powder, the granular powder The powder was calcined at 200° C. for 0.5 h in a tube vacuum furnace under argon protection to obtain material A.

[0047] The above-mentioned material A, 5g polyacrylic acid, 0.25g carbon fiber and 172.5g Ks-6 were dispersed in a mixed solvent of 700g water and 100g ethanol, ball milled for 3h, and then spray-dried to obtain a granular powder, which was placed in a tube Material B was obtained by calcining at 300° C. for 0.5 h in a vacuum furnace under the protection of argon.

[0048] Take 15g of the above-mentioned material B and 5g of medium-temperature pitch and disperse in 25g of toluene, stir and mix to obtain a paste mixture C, put the paste C into a vacuum tube furnace, protect it with argon, and calcin...

Embodiment 3

[0051] Get 34.5g silicon nanoparticles (particle size D50 is 100nm), 10g glucose and 2.5g S-p are dispersed in the mixed solvent of 1000g water and 100g ethanol, through ultrafine ball milling 1h, then through spray drying, obtain granular powder, the particle The powder was calcined at 200° C. for 0.5 h in a tube vacuum furnace under the protection of argon to obtain material A.

[0052] The above-mentioned material A, 10g polyacrylic acid, 0.25g carbon fiber and 172.5g Ks-6 were dispersed in a mixed solvent of 700g water and 100g ethanol, ball milled for 2h, and then spray-dried to obtain granular powder. Material B was obtained by calcining at 300° C. for 0.5 h in a vacuum furnace under the protection of argon.

[0053] Disperse 15g of the above-mentioned material B and 7.25g of medium-temperature pitch in 40g of toluene, stir and mix to obtain a paste mixture C, put the paste mixture C in a vacuum tube furnace, protect it with argon, and calcinate at 950°C for 120min to ob...

technical field

[0001] The invention relates to a silicon-based composite negative electrode material for lithium-ion batteries and a preparation method thereof, belonging to the technical field of lithium-ion batteries. Background technique

[0002] Due to its performance advantages, lithium-ion batteries have been used in various mobile energy storage, such as laptops, mobile phones and cameras. With the development of lithium-ion batteries, lithium-ion batteries with high specific energy, long life and low cost that can be applied to electric vehicles and large-scale energy storage power stations will become the focus of research. At present, the development and progress of cathode materials, one of the main factors determining battery performance, has laid the foundation for the research and development of high-performance lithium-ion batteries; however, graphite-based commercial anode materials are limited by their specific capacity (theoretical specific capacity is 372...

Examples

Embodiment 1

[0040] Get 23g silicon nanoparticles (particle size D50 is 100nm), 10g glucose and 2.5g S-p are dispersed in the mixed solvent of 700g water and 100g ethanol, through ultrafine ball milling 1h, then through spray drying, obtain granular powder, the granular powder The powder was calcined at 200° C. for 0.5 h in a tube vacuum furnace under argon protection to obtain material A.

[0041] The above-mentioned material A, 5g polyacrylic acid, 0.25g carbon fiber and 172.5g Ks-6 were dispersed in a mixed solvent of 700g water and 100g ethanol, ball milled for 2h, and then spray-dried to obtain a granular powder. Material B was obtained by calcining at 300° C. for 0.5 h in a vacuum furnace under the protection of argon.

[0042] Take 15g of the above-mentioned material B and 5g of medium-temperature pitch and disperse in 25g of toluene, stir and mix to obtain a paste mixture C, put the paste C into a vacuum tube furnace, protect it with argon, and calcinate at 1050°C for 90min to obta...

Embodiment 2

[0046] Get 23g silicon nanoparticles (particle diameter D50 is 500nm), 10g glucose and 2.5g S-p are dispersed in the mixed solvent of 500g water and 100g ethanol, through ultrafine ball milling 3h, then through spray drying, obtain granular powder, the granular powder The powder was calcined at 200° C. for 0.5 h in a tube vacuum furnace under argon protection to obtain material A.

[0047] The above-mentioned material A, 5g polyacrylic acid, 0.25g carbon fiber and 172.5g Ks-6 were dispersed in a mixed solvent of 700g water and 100g ethanol, ball milled for 3h, and then spray-dried to obtain a granular powder, which was placed in a tube Material B was obtained by calcining at 300° C. for 0.5 h in a vacuum furnace under the protection of argon.

[0048] Take 15g of the above-mentioned material B and 5g of medium-temperature pitch and disperse in 25g of toluene, stir and mix to obtain a paste mixture C, put the paste C into a vacuum tube furnace, protect it with argon, and calcin...

Embodiment 3

[0051] Get 34.5g silicon nanoparticles (particle size D50 is 100nm), 10g glucose and 2.5g S-p are dispersed in the mixed solvent of 1000g water and 100g ethanol, through ultrafine ball milling 1h, then through spray drying, obtain granular powder, the particle The powder was calcined at 200° C. for 0.5 h in a tube vacuum furnace under the protection of argon to obtain material A.

[0052] The above-mentioned material A, 10g polyacrylic acid, 0.25g carbon fiber and 172.5g Ks-6 were dispersed in a mixed solvent of 700g water and 100g ethanol, ball milled for 2h, and then spray-dried to obtain granular powder. Material B was obtained by calcining at 300° C. for 0.5 h in a vacuum furnace under the protection of argon.

[0053] Disperse 15g of the above-mentioned material B and 7.25g of medium-temperature pitch in 40g of toluene, stir and mix to obtain a paste mixture C, put the paste mixture C in a vacuum tube furnace, protect it with argon, and calcinate at 950°C for 120min to ob...

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