WO2020019655A1

WO2020019655A1 - Conductive coating aluminum foil for lithium ion battery and preparation method therefor

Info

Publication number: WO2020019655A1
Application number: PCT/CN2018/122843
Authority: WO
Inventors: 张全成; 吴永新
Original assignee: 江苏常铝铝业股份有限公司
Priority date: 2018-07-26
Filing date: 2018-12-21
Publication date: 2020-01-30
Also published as: CN109037692A; CN109037692B

Abstract

Disclosed are a conductive coating aluminum foil for a lithium ion battery and a preparation method therefor, comprising an aluminum foil body and a conductive coating. The conductive coating is uniformly coated on the two surfaces of the aluminum foil; the conductive coating comprises the following components in parts by weight: 85-95 parts of environment-friendly adhesive, 5-15 parts of conductive filler, and 1-3 parts of surfactant; the preparation method comprises the following steps: 1. providing the conductive coating; 2. performing surface treatment of the aluminum foil; 3. coating the conductive coating; 4. performing coating forming. In the present disclosure, by means of the reasonable formula design of conductive paste and the effective coating process, the conductive coating can be firmly adhered to the surfaces of the aluminum foil, and the conductive effect of the coating is remarkable, and moreover, an adhesive system is safe and environment-friendly. The obtained aluminum foil for the lithium ion battery can significantly reduce the internal resistance of the battery, improve the diffusion rate of lithium ions, make the battery excellent in cycle performance and low-temperature resistance, and prolong the service life of the battery.

Description

Conductive coating aluminum foil for lithium ion battery and preparation method thereof

Cross-reference to related applications

This application claims priority from Chinese patent applications filed on July 26, 2018 with the application number of 201810835787.1, filed with the State Intellectual Property Office of the People's Republic of China, entitled "A kind of conductive coating aluminum foil for lithium ion batteries and preparation method thereof" The contents are incorporated herein by reference.

Technical field

The present disclosure relates to the field of aluminum foil, and in particular, to a conductive coating aluminum foil for a lithium ion battery and a preparation method thereof.

Background technique

LiFePO ₄ has a high specific capacity (about 170mah / g), a gentle charge and discharge platform, good reversibility, high safety, cheap and easy to prepare, and is environmentally friendly, making it the best choice for the positive electrode material of power batteries. In order to improve the performance of lithium iron phosphate batteries, make them more suitable for energy storage and electric vehicle applications, and improve the conductivity and thermal conductivity of pole pieces, it is an ideal way to improve the performance of power lithium-ion batteries. At present, most of the pole pieces are modified with highly conductive materials to improve the conductivity of the pole pieces.

However, most of the existing improvement methods are directly coating the carbon conductive paste with a coating machine on the aluminum foil, and drying the heated flowing gas. The conductive coating aluminum foil obtained by this method has poor coating adhesion and is easy to fall off. The improvement of the conductive effect is limited, and the coating uses an organic volatile system, which affects environmental safety and other shortcomings.

Summary of the Invention

The technical problems mainly solved by the present disclosure include, for example, providing a conductive coating aluminum foil for lithium ion batteries and a preparation method thereof, which can solve the above-mentioned disadvantages of the existing conductive coating aluminum foil.

In order to solve the above technical problem, a technical solution of the present disclosure provides a conductive coating aluminum foil for a lithium ion battery, including: an aluminum foil body and a conductive coating, wherein the conductive coating is evenly coated on both surfaces of the aluminum foil. The conductive coating includes the following components by weight: 85 to 95 parts of an environmentally friendly adhesive, 5 to 15 parts of a conductive filler, and 1 to 3 parts of a surfactant.

In one or more preferred embodiments of the present disclosure, the environmentally friendly adhesive is an acrylate adhesive.

In one or more preferred embodiments of the present disclosure, the conductive filler includes a mixture of conductive carbon nanotubes, conductive graphite, and nano silver oxide in a mass ratio of 1-3: 3-5: 0.5-1.5.

In order to solve the above technical problem, another technical solution of the present disclosure provides a method for preparing a conductive coating aluminum foil for a lithium ion battery, including the following steps:

(1) Configure conductive paint: According to the formula, weigh the conductive filler and surfactant and place them in a stirrer, stir and disperse uniformly at a high speed of 1000-1500r / min, and then add the stirred mixture to the environmentally friendly adhesive. , Stirring and ultrasonic dispersion to obtain the conductive coating;

(2) Surface treatment of aluminum foil: Put the aluminum foil to be coated in the woolen carbon coating box, and then spray the aluminum powder particles on the surface of the aluminum foil with a nitrogen gas stream to remove the oxide layer on the surface of the aluminum foil and form a convex and concave shape on the aluminum foil The rough surface of the aluminum foil, then use a nitrogen gas stream to blow off the aluminum powder particles on the surface of the aluminum foil, and finally attach an anti-oxidation protective film layer on the two surfaces;

(3) Applying a conductive coating: Take out the surface-treated aluminum foil from the textured carbon coating box, expose the surface's anti-oxidation protective film layer, and then quickly spray a uniform layer on both surfaces with a spray gun. (1) the conductive coating prepared in;

(4) Coating forming: First, the aluminum foil with a conductive coating obtained in step (3) is placed in a drying box and vacuum dried to obtain the conductive coating aluminum foil for a lithium ion battery.

In one or more preferred embodiments of the present disclosure, in the step (1), the conditions for the stirring and ultrasonic dispersion are: firstly stirring at a speed of 500 to 800 r / min for 10 to 30 minutes, and then ultrasonically dispersing for more than 30 minutes .

In one or more preferred embodiments of the present disclosure, in the step (1), the high-speed stirring time is 20-30 minutes until the dispersion is uniform.

In one or more preferred embodiments of the present disclosure, in the step (2), the antioxidant protective film layer is a polyester film layer.

In one or more preferred embodiments of the present disclosure, in the step (2), the nitrogen gas stream carries 30% of the aluminum powder particles, which are continuously sprayed on the surface of the aluminum foil at a rate of 3 to 5 m / min. More than 30min.

In one or more preferred embodiments of the present disclosure, in the step (3), the spraying conditions of the conductive coating are: a temperature of 50 to 80 ° C., a spraying rate of 3 to 5 m / min, and a spraying pressure of 0.5 to 2 MPa. , The coating thickness is 5 ~ 8mm.

In one or more preferred embodiments of the present disclosure, in the step (4), the vacuum drying conditions are: a temperature of 85 to 95 ° C., and a degree of vacuum of 0.01 to 0.03 MPa.

In one or more preferred embodiments of the present disclosure, in the step (4), the vacuum drying time is more than 3h.

The present disclosure also provides a pole piece including a current collector, the current collector being the foregoing conductive coating aluminum foil, or the conductive coating aluminum foil prepared by the above preparation method; and an activity on the current collector. material.

In one or more preferred embodiments of the present disclosure, the active material is a positive active material.

In one or more preferred embodiments of the present disclosure, the active material is LiFePO ₄ .

In one or more preferred embodiments of the present disclosure, the charge transfer resistance between the active material and the current collector is more than 50% lower than that of the light aluminum foil.

In one or more preferred embodiments of the present disclosure, the Li ⁺ diffusion rate of the conductive coated aluminum foil is 3.5 times or more that of the light aluminum foil.

The present disclosure also provides a lithium ion battery including the above-mentioned pole piece.

In one or more preferred embodiments of the present disclosure, a lithium ion battery including the conductive coating aluminum foil as a current collector has a reduction in internal resistance of more than 33% and a power density increase of more than 39 compared to a lithium aluminum battery with a light aluminum foil. %.

The beneficial effect of the present disclosure is that the method for preparing the conductive coating aluminum foil for lithium ion batteries of the present disclosure is simple and easy to implement. The reasonable design of the conductive paste formulation and the effective coating process make the conductive coating on the one hand. The layer can be firmly adhered to the surface of aluminum foil. On the other hand, the conductive effect of the coating is significant, and the bonding system is safe and environmentally friendly, and does not pollute the environment. The resulting aluminum foil used in lithium ion batteries can significantly reduce the internal resistance of the battery and increase lithium ions. The diffusion rate makes the battery excellent in cycle performance and low temperature resistance and prolongs its service life.

detailed description

The preferred embodiments of the present disclosure are described in detail below, so that the advantages and features of the present disclosure can be more easily understood by those skilled in the art, so as to define the protection scope of the present disclosure more clearly.

The embodiments of the present disclosure include:

Example 1

The present disclosure discloses a conductive coating aluminum foil for a lithium ion battery, including: an aluminum foil body and a conductive coating, wherein the conductive coating is evenly coated on both surfaces of the aluminum foil; the conductive coating includes the following weight Ingredients: 85 parts of environmentally friendly adhesive, 5 parts of conductive filler, 1 part of surfactant.

Wherein, the environmentally friendly adhesive is an acrylate adhesive; the conductive filler includes a mixture of conductive carbon nanotubes, conductive graphite, and nano silver oxide in a mass ratio of 1: 3: 0.5.

The method for preparing the conductive coating aluminum foil for a lithium ion battery includes the following steps:

(1) Configure conductive paint: mix conductive carbon nanotubes, conductive graphite, and nano silver oxide with a mass ratio of 1: 3: 0.5 to obtain conductive fillers, and then weigh 5 parts of conductive fillers and 1 part of surfactant according to the formula. In a stirrer, stir at a high speed of 1000 r / min for 30 minutes until the dispersion is uniform. Then add the stirring mixture to 85 parts of acrylate adhesive, first stir at 500 r / min for 30 min, and then ultrasonically disperse for 30 min. Above, a uniformly dispersed conductive coating is obtained;

(2) Surface treatment of aluminum foil: Place the aluminum foil to be coated in a woolen carbon coating box, and then use a nitrogen gas stream to carry 30% of the volume of the aluminum powder particles at a rate of 5m / min to continuously spray the aluminum foil surface for 30min. Above, in order to remove the oxide layer on the surface of the aluminum foil, and form a rough surface on the surface of the aluminum foil, and then use a nitrogen gas flow to blow off the aluminum powder particles on the surface of the aluminum foil, and finally attach a polyester film layer on its two surfaces as a resistance Oxidize the protective film layer to prevent the surface of the aluminum foil from being oxidized again;

(3) Applying a conductive coating: Take out the surface-treated aluminum foil from the textured carbon coating box, expose the surface's anti-oxidation protective film layer, and then quickly spray a uniform layer on both surfaces with a spray gun. (1) The conductive coating prepared in (1), wherein the spraying conditions of the conductive coating are: a temperature of 50 ° C., a spraying rate of 5 m / min, a spraying pressure of 2 MPa, and a coating thickness of 5 to 8 mm;

(4) Coating molding: first put the aluminum foil with a conductive coating obtained in step (3) into a drying box, and vacuum-dry for more than 3 hours under the conditions of a temperature of 85 ° C and a vacuum of 0.01-0.03 MPa to obtain The conductive coating aluminum foil for a lithium ion battery.

Example 2

The present disclosure discloses a conductive coating aluminum foil for a lithium ion battery, including: an aluminum foil body and a conductive coating, wherein the conductive coating is evenly coated on both surfaces of the aluminum foil; the conductive coating includes the following weight Ingredients: 95 parts of environmentally friendly adhesive, 15 parts of conductive filler, 3 parts of surfactant.

The environmentally friendly adhesive is an acrylate adhesive; the conductive filler includes a mixture of conductive carbon nanotubes, conductive graphite, and nano silver oxide in a mass ratio of 3: 5: 1.5.

(1) Configure conductive paint: conductive carbon nanotubes, conductive graphite and nano silver oxide are mixed at a mass ratio of 3: 5: 1.5 to obtain conductive fillers, and then 15 parts of conductive fillers and 3 parts of surfactant are weighed according to the formula. In a stirrer, stir at a high speed of 1500 r / min for 20 minutes until the dispersion is uniform, then add the stirring mixture to 95 parts of acrylate adhesive, stir and ultrasonically disperse for more than 30 minutes to obtain the conductive coating;

(2) Surface treatment of aluminum foil: Put the aluminum foil to be coated in the woolen carbon coating box, and then carry the aluminum powder particles which account for 40% of the air volume with a nitrogen gas stream, and continuously spray the aluminum foil surface at a rate of 3m / min for 20min. Above, in order to remove the oxide layer on the surface of the aluminum foil, and form a rough surface on the surface of the aluminum foil, and then use a nitrogen gas flow to blow off the aluminum powder particles on the surface of the aluminum foil, and finally attach a polyester film layer on its two surfaces as a resistance Oxidize the protective film layer to prevent the surface of the aluminum foil from being oxidized again;

(3) Applying a conductive coating: Take out the surface-treated aluminum foil from the textured carbon coating box, expose the surface's anti-oxidation protective film layer, and then quickly spray a uniform layer on both surfaces with a spray gun. The conductive coating prepared in (1); the spraying conditions of the conductive coating are: a temperature of 80 ° C., a spraying rate of 3 m / min, a spraying pressure of 0.5 MPa, and a coating thickness of 5 to 8 mm.

(4) Coating forming: First, the aluminum foil with a conductive coating obtained in step (3) is placed in a drying box and vacuum dried to obtain the conductive coating aluminum foil for a lithium ion battery. The vacuum drying conditions are: a temperature of 95 ° C, and a degree of vacuum of 0.01 to 0.03 MPa.

The conductive coating aluminum foil for lithium ion batteries obtained by the above method is added and made into pole pieces for use in lithium ion batteries. After testing, the charge transfer resistance between the active material and the current collector is 50% lower than that of light aluminum foil. The Li ⁺ diffusion rate is 3.5 times higher than that of the light aluminum foil. The coated aluminum foil as a current collector can reduce the internal resistance of the assembled full battery. Compared with the light aluminum foil, the internal resistance decreases by more than 33%, and the power density increases by more than 39%. In addition, the cycle performance and low temperature performance of the lithium-ion battery are significantly improved, and the service life is long.

The above descriptions are merely preferred embodiments of the present disclosure, and are not intended to limit the present disclosure. For those skilled in the art, the present disclosure may have various modifications and changes. Any modification, equivalent replacement, or improvement made within the spirit and principle of this disclosure shall be included in the protection scope of this disclosure.

Industrial applicability

The method for preparing the conductive coating aluminum foil for lithium ion batteries disclosed in the present disclosure is simple and easy to implement. The reasonable design of the conductive paste formula and effective coating process make the conductive coating firmly adhere to On the surface of aluminum foil, on the other hand, the conductive effect of the coating is significant, and the bonding system is safe and environmentally friendly, and does not pollute the environment. The resulting aluminum foil used in lithium ion batteries can significantly reduce the internal resistance of the battery, increase the lithium ion diffusion rate, and make the battery's Excellent cycle performance and low temperature resistance, extended service life, suitable for industrial production.

Claims

A conductive coating aluminum foil for a lithium ion battery, comprising: an aluminum foil body and a conductive coating, wherein the conductive coating is evenly coated on both surfaces of the aluminum foil; the conductive coating includes the following weight Parts of components: 85 to 95 parts of environmentally friendly adhesives, 5 to 15 parts of conductive fillers, and 1 to 3 parts of surfactants.
The conductive coating aluminum foil for a lithium ion battery according to claim 1, wherein the environmentally friendly adhesive is an acrylate adhesive.
The conductive coating aluminum foil for a lithium ion battery according to claim 1, wherein the conductive filler comprises conductive carbon nanotubes, conductive graphite, and nano-silver oxide with a mass of 1 to 3: 3 to 5: 0.5 to 1.5. Than mixed mixture.
A method for preparing a conductive coating aluminum foil for a lithium ion battery according to any one of claims 1 to 3, comprising the following steps:

(1) Configure conductive paint: According to the formula, weigh the conductive filler and surfactant and place them in a stirrer, stir and disperse uniformly at a high speed of 1000-1500r / min, and then add the stirred mixture to the environmentally friendly adhesive. , Stirring and ultrasonic dispersion to obtain the conductive coating;

(2) Surface treatment of aluminum foil: Put the aluminum foil to be coated in the woolen carbon coating box, and then spray the aluminum powder particles on the surface of the aluminum foil with a nitrogen gas stream to remove the oxide layer on the surface of the aluminum foil and form a convex and concave shape on the surface of the aluminum foil. The rough surface of the aluminum foil, then use a nitrogen gas stream to blow off the aluminum powder particles on the surface of the aluminum foil, and finally attach an anti-oxidation protective film layer on the two surfaces;

(3) Applying a conductive coating: Take out the surface-treated aluminum foil from the textured carbon coating box, expose the surface's anti-oxidation protective film layer, and then quickly spray a uniform layer on both surfaces with a spray gun. (1) the conductive coating prepared in;

(4) Coating forming: First, the aluminum foil with a conductive coating obtained in step (3) is placed in a drying box and vacuum dried to obtain the conductive coating aluminum foil for a lithium ion battery.
The method for preparing a conductive coating aluminum foil for a lithium ion battery according to claim 4, wherein in the step (1), the high-speed stirring time is 20-30 minutes until the dispersion is uniform.
The method for preparing a conductive coating aluminum foil for a lithium ion battery according to claim 4, characterized in that, in the step (1), the conditions for the stirring and ultrasonic dispersion are: firstly at a rotation speed of 500 to 800 r / min Stir for 10 to 30 minutes, then disperse by ultrasound for more than 30 minutes.
The method for preparing a conductive coating aluminum foil for a lithium ion battery according to claim 4, wherein in the step (2), the antioxidant protective film layer is a polyester film layer.
The method for preparing a conductive coating aluminum foil for a lithium ion battery according to claim 4, characterized in that, in the step (2), the nitrogen gas stream carries aluminum powder particles occupying 30 to 40% of the volume of the gas stream. The rate of ˜5 m / min is continuously sprayed onto the surface of the aluminum foil for 20 to 30 minutes or more.
The method for preparing a conductive coating aluminum foil for a lithium ion battery according to claim 4, wherein in the step (3), the spraying conditions of the conductive coating are: a temperature of 50 to 80 ° C, and a spraying rate of 3 ～ 5m / min, spray pressure is 0.5 ～ 2MPa, coating thickness is 5 ～ 8mm.
The method for preparing a conductive coating aluminum foil for a lithium ion battery according to claim 4, wherein in the step (4), the vacuum drying time is 3 hours or more.
The method for preparing a conductive coating aluminum foil for a lithium ion battery according to claim 4, wherein in the step (4), the vacuum drying conditions are: a temperature of 85 to 95 ° C, and a degree of vacuum of 0.01 to 0.03 MPa. .
A pole piece including

A current collector, which is the conductive coated aluminum foil according to any one of claims 1 to 3, or the conductive coated aluminum foil prepared by the preparation method according to any one of claims 4 to 11; and

Active material on the current collector.
The pole piece according to claim 12, wherein the active material is a positive electrode active material.
Pole piece 12 or claim 13, wherein the active material is LiFePO 4.
The pole piece according to claim 12, wherein the charge transfer resistance between the active material and the current collector is 50% lower than that of the light aluminum foil.
The pole piece according to claim 12, wherein the Li + diffusion rate of the conductive coating aluminum foil is 3.5 times or more than that of the light aluminum foil.
A lithium ion battery comprising the pole piece according to any one of claims 12 to 16.
The lithium-ion battery according to claim 17, wherein the lithium-ion battery has a reduction in internal resistance of more than 33% compared to a lithium-ion battery of light aluminum foil.
The lithium-ion battery according to claim 17, wherein the lithium-ion battery has a power density increase of more than 39% compared to the lithium-ion battery of light aluminum foil.