Silicon-based negative electrode plate, fabrication method thereof and lithium ion battery

Abstract

The invention discloses a silicon-based negative electrode plate, a fabrication method thereof and a lithium ion battery. A negative coating layer of the silicon-based negative electrode provided by the invention comprises a first coating layer and a second coating layer, wherein the first coating layer is arranged on a current collector, the second coating layer is arranged on the first coating layer, an active substance in the first coating layer comprises a silicon-based negative electrode material, an active substance in the second coating layer does not comprise a silicon-based negative electrode material, and lithium is contained in a surface of the second coating layer. The fabrication method comprises the steps of 1) coating first paste comprising the silicon-based negative electrode material on the current collector to form the first coating layer; 2) coating second paste which does not contain the silicon-based negative electrode material on the first coating layer to form the second coating layer; and 3) performing lithium doping on a pole plate comprising the second coating layer in advance to obtain the silicon-based negative electrode plate. With the silicon-based negative electrode plate provided by the invention, direct contact of the silicon-based material and metal lithium is prevented during the lithium doping process of the pole plate comprising the silicon-based negative electrode material in advance, and the energy density and the cycle stability are remarkably improved.

Description

technical field

[0001] The invention belongs to the technical field of energy storage, and relates to a pole piece and its preparation method and application, in particular to a silicon-based negative pole piece, its preparation method and a lithium ion battery. Background technique

[0002] Due to the advantages of high voltage, high energy density, high cycle life, low self-discharge rate, light weight and no memory effect, lithium-ion batteries have achieved a wide range of applications in various fields. With the continuous improvement of the capacity requirements of lithium-ion batteries for electrical equipment, people's expectations for the energy density of lithium-ion batteries are getting higher and higher. In addition to traditional digital products, energy storage equipment, electric tools, electric vehicles, etc. are also constantly developing lithium-ion batteries with lighter weight, smaller volume, higher output voltage and power density, and the development ...

Examples

Embodiment 1

[0077] This embodiment provides a silicon-based negative electrode sheet. The negative electrode coating of the silicon-based negative electrode sheet includes a first coating layer coated on a copper foil current collector and a second coating layer coated on the first coating layer.

[0078] The first coating includes an active material, a conductive agent and a binder, wherein the active material is silicon oxide SiO 0.9 , the conductive agent is graphite powder, and the binder is sodium carboxymethyl cellulose. In the first coating, the mass fraction of the active material is 80%, the mass fraction of the conductive agent is 5%, and the mass fraction of the binder is 15%.

[0079] The second coating includes an active material, a conductive agent and a binder, wherein the active material is natural graphite, the conductive agent is graphite powder, and the binder is sodium carboxymethyl cellulose. In the second coating, the mass fraction of the active material is 94%, the...

Embodiment 2

[0089] This embodiment provides a silicon-based negative electrode sheet. The negative electrode coating of the silicon-based negative electrode sheet includes a first coating layer coated on a copper foil current collector and a second coating layer coated on the first coating layer.

[0090] The first coating includes an active material, a conductive agent and a binder, wherein the active material is silicon oxide SiO 0.5With artificial graphite (mass ratio 25:75), the conductive agent is carbon black, and the binder is polyvinylidene fluoride. In the first coating, the mass fraction of the active material is 88%, the mass fraction of the conductive agent is 4%, and the mass fraction of the binder is 8%.

[0091] The second coating includes an active material, a conductive agent and a binder, wherein the active material is artificial graphite, the conductive agent is carbon black, and the binder is polyvinylidene fluoride. In the second coating, the mass fraction of the act...

Embodiment 3

[0101] This embodiment provides a silicon-based negative electrode sheet. The negative electrode coating of the silicon-based negative electrode sheet includes a first coating layer coated on a copper foil current collector and a second coating layer coated on the first coating layer.

[0102] The first coating includes an active material, a conductive agent and a binder, wherein the active material is silicon oxide SiO 0.2 With artificial graphite (mass ratio 13:87), the conductive agent is acetylene black, and the binder is styrene-butadiene rubber. In the first coating, the mass fraction of the active material is 92%, the mass fraction of the conductive agent is 2%, and the mass fraction of the binder is 6%.

[0103] The second coating includes an active material, a conductive agent and a binder, wherein the active material is an amorphous carbon material (hard carbon), the conductive agent is acetylene black, and the binder is sodium carboxymethyl cellulose. In the second...

technical field

[0001] The invention belongs to the technical field of energy storage, and relates to a pole piece and its preparation method and application, in particular to a silicon-based negative pole piece, its preparation method and a lithium ion battery. Background technique

[0002] Due to the advantages of high voltage, high energy density, high cycle life, low self-discharge rate, light weight and no memory effect, lithium-ion batteries have achieved a wide range of applications in various fields. With the continuous improvement of the capacity requirements of lithium-ion batteries for electrical equipment, people's expectations for the energy density of lithium-ion batteries are getting higher and higher. In addition to traditional digital products, energy storage equipment, electric tools, electric vehicles, etc. are also constantly developing lithium-ion batteries with lighter weight, smaller volume, higher output voltage and power density, and the development ...

Examples

Embodiment 1

[0077] This embodiment provides a silicon-based negative electrode sheet. The negative electrode coating of the silicon-based negative electrode sheet includes a first coating layer coated on a copper foil current collector and a second coating layer coated on the first coating layer.

[0078] The first coating includes an active material, a conductive agent and a binder, wherein the active material is silicon oxide SiO 0.9 , the conductive agent is graphite powder, and the binder is sodium carboxymethyl cellulose. In the first coating, the mass fraction of the active material is 80%, the mass fraction of the conductive agent is 5%, and the mass fraction of the binder is 15%.

[0079] The second coating includes an active material, a conductive agent and a binder, wherein the active material is natural graphite, the conductive agent is graphite powder, and the binder is sodium carboxymethyl cellulose. In the second coating, the mass fraction of the active material is 94%, the...

Embodiment 2

[0089] This embodiment provides a silicon-based negative electrode sheet. The negative electrode coating of the silicon-based negative electrode sheet includes a first coating layer coated on a copper foil current collector and a second coating layer coated on the first coating layer.

[0090] The first coating includes an active material, a conductive agent and a binder, wherein the active material is silicon oxide SiO 0.5With artificial graphite (mass ratio 25:75), the conductive agent is carbon black, and the binder is polyvinylidene fluoride. In the first coating, the mass fraction of the active material is 88%, the mass fraction of the conductive agent is 4%, and the mass fraction of the binder is 8%.

[0091] The second coating includes an active material, a conductive agent and a binder, wherein the active material is artificial graphite, the conductive agent is carbon black, and the binder is polyvinylidene fluoride. In the second coating, the mass fraction of the act...

Embodiment 3

[0101] This embodiment provides a silicon-based negative electrode sheet. The negative electrode coating of the silicon-based negative electrode sheet includes a first coating layer coated on a copper foil current collector and a second coating layer coated on the first coating layer.

[0102] The first coating includes an active material, a conductive agent and a binder, wherein the active material is silicon oxide SiO 0.2 With artificial graphite (mass ratio 13:87), the conductive agent is acetylene black, and the binder is styrene-butadiene rubber. In the first coating, the mass fraction of the active material is 92%, the mass fraction of the conductive agent is 2%, and the mass fraction of the binder is 6%.

[0103] The second coating includes an active material, a conductive agent and a binder, wherein the active material is an amorphous carbon material (hard carbon), the conductive agent is acetylene black, and the binder is sodium carboxymethyl cellulose. In the second...

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