CN115148946A - Preparation method of positive pole piece of lithium-sulfur battery and lithium-sulfur battery - Google Patents

Preparation method of positive pole piece of lithium-sulfur battery and lithium-sulfur battery Download PDF

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Publication number
CN115148946A
CN115148946A CN202210936070.2A CN202210936070A CN115148946A CN 115148946 A CN115148946 A CN 115148946A CN 202210936070 A CN202210936070 A CN 202210936070A CN 115148946 A CN115148946 A CN 115148946A
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sulfur
lithium
pole piece
positive pole
heating
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吴飞翔
周金伟
刘家敏
刘文新
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Central South University
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Central South University
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/04Processes of manufacture in general
    • H01M4/0471Processes of manufacture in general involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/05Accumulators with non-aqueous electrolyte
    • H01M10/052Li-accumulators
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/13Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139Processes of manufacture
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/36Selection of substances as active materials, active masses, active liquids
    • H01M4/362Composites

Abstract

The invention belongs to the technical field of lithium-sulfur batteries, and particularly discloses a preparation method of a lithium-sulfur battery positive pole piece with gradient distribution of sulfur, which comprises the steps of uniformly mixing a carbon material and sulfur powder to obtain sulfur-carbon powder; heating the sulfur-carbon powder to obtain a sulfur-carbon composite material; mixing the sulfur-carbon composite material with a conductive agent, a binder and a solvent to obtain slurry; coating the slurry on a current collector, and heating to form a positive pole piece; and (4) heating the positive pole piece obtained in the step (S3) in a heating device in a manner that the current collector is arranged above and the coating slurry is arranged below, so as to obtain the lithium-sulfur battery positive pole piece with sulfur gradient distribution. The invention constructs the lithium-sulfur positive pole piece with sulfur gradient distribution only by controlling the heating mode of the lithium-sulfur battery positive pole piece, and the method is simple, high in efficiency, environment-friendly in treatment process and suitable for large-scale industrial production. The invention also discloses application of the positive pole piece prepared by the preparation method in a lithium-sulfur battery.

Description

Preparation method of positive pole piece of lithium-sulfur battery and lithium-sulfur battery
Technical Field
The invention belongs to the technical field of lithium-sulfur batteries, and particularly relates to a preparation method of a positive pole piece of a lithium-sulfur battery.
Background
The development of the clean energy storage industry is greatly promoted by energy crisis and environmental pollution. Meanwhile, the living standard of people is continuously improved, so that people more pursue electronic products with high power and high energy consumption, such as electric automobiles, digital products and the like. Currently, the mainstream positive electrode materials, such as lithium iron phosphate, lithium cobaltate and high nickel ternary positive electrode materials, have relatively limited specific capacity. The development of the anode material with high specific capacity becomes the focus of the majority of researchers.
The element sulfur is used as a light and multi-electron reaction anode material and has large specific capacity (1675 mAh g) -1 ) Environment-friendly, abundant and cheap reserves and the like. However, lithium sulfur batteries as next generation high specific energy batteries, the dissolution loss and shuttling effect of the intermediate polysulfide severely deteriorate the positive and negative electrode transport interface and the cycling stability.
Disclosure of Invention
Aiming at the problems in the prior art, the invention aims to provide a preparation method of a lithium-sulfur battery positive pole piece with gradient distribution of sulfur. Starting from the positive pole piece of the lithium-sulfur battery, the positive pole piece of the lithium-sulfur battery with the sulfur gradient distribution is constructed, the sulfur gradient distribution structure can greatly inhibit the dissolution of polysulfide, the shuttle effect is reduced, the performance of the battery is greatly improved, and the service life of the battery is prolonged.
In order to achieve the above object, the present invention provides the following specific technical solutions.
A preparation method of a lithium-sulfur battery positive pole piece with gradient distribution of sulfur comprises the following steps:
step S1, uniformly mixing a carbon material and sulfur powder to obtain sulfur-carbon powder;
s2, heating the sulfur-carbon powder to obtain a sulfur-carbon composite material;
s3, mixing the sulfur-carbon composite material with a conductive agent, a binder and a solvent to obtain slurry; coating the slurry on a current collector, and heating to form a positive pole piece;
and S4, heating the positive pole piece obtained in the step S3 in a heating device in a mode that a current collector is arranged above and slurry is coated below, and obtaining the lithium-sulfur battery positive pole piece with sulfur gradient distribution.
Further, in some preferred embodiments of the present invention, the carbon material is one or more of ketjen black, acetylene black, graphite, graphene, porous carbon spheres; the sulfur powder is sublimed sulfur powder.
Further, in some preferred embodiments of the present invention, the mixing mass ratio of the carbon material and the sulfur powder is 1: (0.4 to 0.8).
Further, in some preferred embodiments of the present invention, the heating temperature in step S2 is 100 to 160 ℃, and the heating time is 4 to 20h.
Further, in some preferred embodiments of the present invention, the conductive agent is at least one of acetylene black, super P; the binder is oil-based binder PVDF or water-based binder CMC.
Further, in some preferred embodiments of the present invention, the solvent is one of NMP, absolute ethanol, and deionized water.
Further, in a preferred embodiment of the present invention, in the slurry, a mass ratio of the sulfur-carbon composite material to the conductive agent to the binder is 7 to 9:2 to 0.5:1 to 0.5.
Further, in some preferred embodiments of the present invention, the heating temperature in step S3 is 40 to 70 ℃, and the heating time is 6 to 24h.
Further, in some preferred embodiments of the present invention, the heating device is selected from one of a hot plate, an oven, or an alcohol lamp.
Further, in a preferred embodiment of the present invention, the heating temperature in step S4 is 60 to 120 ℃, and the heating time is 5 to 120min.
The invention starts from the pole piece directly, the positive pole piece of the lithium-sulfur battery only comprises the aluminum foil and slurry which is coated on the aluminum foil and is mixed by a sulfur-carbon composite material, a conductive agent, a binder and a solvent, other substances are not required to be added, or other coating treatments are carried out on the pole piece, the heating mode that the current collector is coated with the slurry is directly utilized, so that the current collector (the aluminum foil) blocks the escape of sulfur in the heating process, and the positive pole piece of the lithium-sulfur battery with the sulfur gradient distribution that the sulfur content is more on the side of the current collector and the sulfur content is less as the side is farther away from the current collector is constructed.
Based on the same inventive concept, the invention also provides a lithium-sulfur battery, which comprises the lithium-sulfur battery positive pole piece with the gradient distribution of sulfur prepared by the preparation method.
Compared with the prior art, the invention has the following obvious beneficial technical effects:
the lithium-sulfur positive pole piece with the sulfur gradient distribution is constructed only by controlling the heating mode of the positive pole piece of the lithium-sulfur battery, the method is simple, the efficiency is high, the treatment process is environment-friendly, and the method is suitable for large-scale industrial production;
the lithium-sulfur battery positive plate with the sulfur gradient distribution greatly inhibits shuttle of polysulfide, improves the electrochemical performance of the lithium-sulfur battery, prolongs the service life of the battery, and has strong commercial application prospect.
Drawings
Fig. 1 is a schematic diagram of the S direction of a lithium sulfur positive electrode plate during heating.
Fig. 2 is a graph of electrochemical performance of the assembled cells of example 1 and comparative example 1.
Detailed Description
In order to facilitate an understanding of the invention, reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings, and the scope of the invention is not limited to the following specific embodiments.
Unless otherwise defined, all terms of art used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention.
Unless otherwise specifically indicated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.
Example 1
The embodiment comprises the following steps:
(1) Grinding 0.8g of Ketjen black and 1.2g of sublimed sulfur powder in a mortar, and uniformly mixing to obtain sulfur-carbon powder;
(2) Sealing the sulfur-carbon powder mixed in the step (1) in a glass bottle, and heating the glass bottle in a 150 ℃ blast oven for 15 hours to obtain a sulfur-carbon composite material;
(3) Mixing the sulfur-carbon composite material obtained in the step (2) with acetylene black and PVDF according to the mass ratio of 8:1:1, grinding and mixing, adding a proper amount of NMP solvent for size mixing after grinding is uniform, coating the slurry on a current collector aluminum foil after the viscosity of the slurry is moderate, and then placing the pole piece in a 40 ℃ blast oven for drying to obtain a lithium-sulfur positive pole piece;
(4) And (3) as shown in fig. 1, heating the lithium-sulfur positive pole piece obtained in the step (S3) on a 80 ℃ hot table for 30min in a mode that the substrate is arranged on the substrate and the material is arranged on the lower part, and naturally cooling to obtain the lithium-sulfur positive pole piece with the sulfur gradient distribution.
In the heating process, sulfur in the lithium sulfur positive pole piece with the originally uniformly distributed sulfur continuously sublimates under the thermal action and runs to one side of a current collector to form the lithium sulfur positive pole piece with the sulfur in gradient distribution.
Comparative example 1
Comparative example 1 and example 1 differ only in that: there is no step (4).
The lithium sulfur cathode sheet with the gradient distribution of sulfur obtained in example 1, the lithium sulfur cathode sheet obtained in comparative example 1, and a metallic lithium negative electrode, a commercial lithium sulfur electrolyte (1M LiTFSI in dol dme = 1.
As can be seen from FIG. 2, the battery using the lithium-sulfur positive electrode sheet with the sulfur gradient distribution as the positive electrode circulates 300 times under the charge-discharge rate of 1C, and the specific discharge capacity is kept at 581.5 mAh g -1 Above, the capacity attenuation of each cycle is 0.047%, the cycle stability is good, and the coulomb efficiency is always stably kept above 98%. Comparative example 1 the capacity after 300 cycles was only 295.7 mAh g -1 Each ofCapacity fading is as high as 0.18% in one cycle. The lithium-sulfur positive pole piece with gradient sulfur distribution prepared in the embodiment 1 has excellent performance as a lithium-sulfur battery positive pole, and shows good commercialization prospect.
Example 2
The embodiment comprises the following steps:
(1) Grinding 5g of graphite and 2.5g of sublimed sulfur powder in a mortar, and uniformly mixing to obtain sulfur-carbon powder;
(2) Sealing the sulfur-carbon powder mixed in the step (1) in a glass bottle, and heating the glass bottle in a blast oven at 120 ℃ for 18 hours to obtain a sulfur-carbon composite material;
(3) Grinding and mixing the sulfur-carbon composite material obtained in the step (2) with acetylene black and CMC (carboxy methyl cellulose) according to a mass ratio of 7;
(4) And (4) putting the lithium-sulfur positive pole piece obtained in the step (S3) on a hot table at 100 ℃ for heating for 20min in a mode that the substrate is arranged on the base and the material is arranged on the lower part, and then naturally cooling to obtain the lithium-sulfur positive pole piece with sulfur gradient distribution.
Example 3
The embodiment comprises the following steps:
(1) Grinding 4g of porous carbon spheres and 3.2g of sublimed sulfur powder in a mortar, and uniformly mixing to obtain sulfur-carbon powder;
(2) Sealing the sulfur-carbon powder mixed in the step (1) in a glass bottle, and heating the glass bottle in a 150 ℃ blast oven for 10 hours to obtain a sulfur-carbon composite material;
(3) Mixing the sulfur-carbon composite material obtained in the step (2) with Super P and CMC in a mass ratio of 9:0.5:0.1, grinding and mixing, adding a proper amount of ethanol solvent for size mixing after grinding uniformly, coating the slurry on a current collector aluminum foil after the viscosity of the slurry is moderate, and then placing the pole piece in a 70 ℃ blast oven for drying to obtain a lithium-sulfur positive pole piece;
(4) And (4) putting the lithium-sulfur positive pole piece obtained in the step (S3) on a 120 ℃ hot table in a mode that the substrate is arranged on the base and the material is arranged on the lower part, heating for 100min, and naturally cooling to obtain the lithium-sulfur positive pole piece with sulfur gradient distribution.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims (10)

1. A preparation method of a lithium-sulfur battery positive pole piece with gradient distribution of sulfur is characterized by comprising the following steps:
step S1, uniformly mixing a carbon material and sulfur powder to obtain sulfur-carbon powder;
s2, heating the sulfur-carbon powder to obtain a sulfur-carbon composite material;
s3, mixing the sulfur-carbon composite material with a conductive agent, a binder and a solvent to obtain slurry; coating the slurry on a current collector, and heating to form a positive pole piece;
and S4, heating the positive pole piece obtained in the step S3 in a heating device in a mode that a current collector is arranged above and slurry is coated below, and obtaining the lithium-sulfur battery positive pole piece with sulfur gradient distribution.
2. The method according to claim 1, wherein the carbon material is one or more of ketjen black, acetylene black, graphite, graphene, and porous carbon spheres; the sulfur powder is sublimed sulfur powder.
3. The production method according to claim 2, wherein the carbon material and the sulfur powder are mixed in a mass ratio of 1: (0.4 to 0.8).
4. The method according to claim 1, wherein the heating temperature in step S2 is from 100 to 160 ℃, and the heating time is from 4 to 20h.
5. The method according to claim 1, wherein the conductive agent is at least one of acetylene black and Super P; the binder is oil-based binder PVDF or water-based binder CMC.
6. The method of claim 1, wherein the solvent is one of NMP, absolute ethanol, and deionized water.
7. The preparation method according to claim 5 or 6, wherein the mass ratio of the sulfur-carbon composite material to the conductive agent to the binder in the slurry is 7-9: 2 to 0.5:1 to 0.5.
8. The method according to claim 1, wherein the heating temperature in the step S3 is 40 to 70 ℃ and the heating time is 6 to 24h.
9. The method according to claim 1, wherein the temperature for heating in step S4 is from 60 to 120 ℃ and the heating time is from 5 to 120min.
10. A lithium-sulfur battery, characterized by comprising a lithium-sulfur battery positive electrode sheet with gradient distribution of sulfur prepared by the preparation method of any one of claims 1 to 9.
CN202210936070.2A 2022-08-05 2022-08-05 Preparation method of positive pole piece of lithium-sulfur battery and lithium-sulfur battery Pending CN115148946A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115548320A (en) * 2022-10-31 2022-12-30 南昌大学 Concentration gradient type Te x Se y S z Composite cathode material and preparation method and application thereof

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115548320A (en) * 2022-10-31 2022-12-30 南昌大学 Concentration gradient type Te x Se y S z Composite cathode material and preparation method and application thereof
CN115548320B (en) * 2022-10-31 2023-10-31 南昌大学 Concentration gradient Te x Se y S z Composite positive electrode material, preparation method and application thereof

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