CN114597347A - Solid-state lithium-sulfur battery positive electrode and preparation method thereof, and solid-state lithium-sulfur battery and preparation method thereof - Google Patents

Solid-state lithium-sulfur battery positive electrode and preparation method thereof, and solid-state lithium-sulfur battery and preparation method thereof Download PDF

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CN114597347A
CN114597347A CN202210251475.2A CN202210251475A CN114597347A CN 114597347 A CN114597347 A CN 114597347A CN 202210251475 A CN202210251475 A CN 202210251475A CN 114597347 A CN114597347 A CN 114597347A
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lithium
solid
positive electrode
salt
sulfur battery
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周光敏
成会明
李闯
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Shenzhen International Graduate School of Tsinghua University
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1397—Processes of manufacture of electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Abstract

The invention provides a solid-state lithium-sulfur battery anode and a preparation method thereof, and a solid-state lithium-sulfur battery and a preparation method thereof, wherein the solid-state lithium-sulfur battery anode comprises an anode material conductive current collector and a coating material coated on the anode material conductive current collector, the coating material comprises an organic sulfur material, a high-salt solid electrolyte and a conductive agent, and the high-salt solid electrolyte comprises a lithium salt and a high polymer material; wherein at least part of the lithium ions are stored in the-S-bonds of the organosulfur material. Lithium ions are stored in an organic sulfur material-S-S-bond in a form similar to the lithium iron phosphate positive electrode material embedded lithium storage mode, so that the reaction energy barrier in the sulfur charging and discharging process is greatly reduced, the volume change is small, and the solid lithium sulfur battery can operate at room temperature and normal pressure.

Description

Solid-state lithium-sulfur battery positive electrode and preparation method thereof, and solid-state lithium-sulfur battery and preparation method thereof
Technical Field
The invention relates to the technical field of electrochemical energy storage, in particular to a solid-state lithium-sulfur battery anode and a preparation method thereof, and a solid-state lithium-sulfur battery and a preparation method thereof.
Background
Under the large background of global energy shortage, environmental pollution and climate abnormality, new energy represented by electric vehicles has received much attention from people. However, in the conventional lithium ion battery, the further development of the electric vehicle is hindered by the limited energy density and the safety problem caused by the combustible electrolyte. The liquid electrolyte is replaced by the solid electrolyte, and the traditional graphite cathode is replaced by the lithium metal, so that the problems of low energy density and safety of the traditional lithium ion battery can be solved simultaneously. Among the solid-state lithium batteries, the solid-state lithium sulfur battery is considered to be the most competitive next-generation energy storage system due to high energy density (2600Wh/kg) and high safety. However, the development of solid-state lithium sulfur batteries is challenged by a number of major challenges: (1) sulfur is an insulator, and the ionic conductivity and the electronic conductivity of the sulfur are poor; (2) solid phase sulfur and solid phase lithium sulfide (Li)2S) slow redox kinetics; (3) the large volume change (80%) of sulfur during charging and discharging causes the separation of sulfur, conductive agent and solid electrolyte. In the prior art, the solid-state lithium-sulfur battery cannot meet the long-term stability at normal temperature, and aiming at the problem, partial scholars promote the solid-solid reaction of sulfur by adding a catalyst, but the solid-solid contact interface is limited, and the catalyst has a limited effect. The volumetric expansion effect of sulfur is well known to the scholars by applying large pressure, but the practical application of solid-state lithium-sulfur batteries presents new challenges.
The prior art lacks a solid-state lithium-sulfur battery which is stable for a long time at normal temperature and normal pressure.
The above background disclosure is only for the purpose of assisting understanding of the concept and technical solution of the present invention and does not necessarily belong to the prior art of the present patent application, and should not be used for evaluating the novelty and inventive step of the present application in the case that there is no clear evidence that the above content is disclosed at the filing date of the present patent application.
Disclosure of Invention
The invention provides a solid-state lithium-sulfur battery anode and a preparation method thereof, and a solid-state lithium-sulfur battery and a preparation method thereof, aiming at solving the existing problems.
In order to solve the above problems, the technical solution adopted by the present invention is as follows:
a solid-state lithium-sulfur battery positive electrode comprises a positive electrode material conductive current collector and a coating material coated on the positive electrode material conductive current collector, wherein the coating material comprises an organic sulfur material, a high-salt solid electrolyte and a conductive agent, and the high-salt solid electrolyte comprises lithium salt and a high polymer material; wherein at least part of the lithium ions are stored in the-S-bonds of the organosulfur material.
Preferably, the sulfur in the organic sulfur material is grafted on the organic polymer material in a form of covalent bond.
Preferably, the organic polymer material is polyacrylonitrile, dimethyl trisulfide, diphenyl trisulfide or diphenyl tetrasulfide.
Preferably, the lithium salt is LiFSI, LiTFSI, LiClO4At least one of (1); the high polymer material is at least one of polyvinylidene fluoride, poly (vinylidene fluoride-co-hexafluoropropylene) and polyacrylonitrile; the mass ratio of the lithium salt to the high polymer material is 1: 1; the mass ratio of the organic sulfur material, the high-salt solid electrolyte and the conductive agent is 1-4:1-4: 1-4.
The invention also provides a preparation method of the solid-state lithium-sulfur battery positive electrode, which is used for preparing the solid-state lithium-sulfur battery positive electrode, and comprises the following steps: s1: dissolving lithium salt and a high polymer material in an organic solvent, and stirring to obtain a high-salt solid electrolyte solution; s2: grinding an organic sulfur material and a conductive agent, adding the high-salt solid electrolyte solution, and continuously stirring until positive electrode slurry is obtained; s3: coating the positive electrode slurry on a conductive current collector of a positive electrode material, and removing an organic solvent to obtain the positive electrode; wherein at least part of the lithium ions are stored in the-S-bonds of the organosulfur material.
The invention further provides a solid-state lithium-sulfur battery, which is characterized by comprising a solid electrolyte film, the positive electrode and the lithium negative electrode; the solid electrolyte film comprises lithium salt and a high polymer material.
Preferably, the lithium salt in the solid electrolyte film is LiFSI, LiTFSI, LiClO4At least one of(ii) a The high polymer material is at least one of polyvinylidene fluoride, poly (vinylidene fluoride-co-hexafluoropropylene) and polyacrylonitrile; the mass of the lithium salt of the solid electrolyte film is greater than or equal to that of the high polymer material.
Preferably, the concentration of the lithium salt is 0.1-0.3g/mL, and the concentration of the high molecular material is 0.1-0.3 g/mL.
The invention also provides a preparation method of the solid-state lithium-sulfur battery, which comprises the following steps: t1: preparing a high-salt solid electrolyte film: mixing lithium salt, a high polymer material and an organic solvent, coating the mixture on a glass plate by scraping, and removing the organic solvent to obtain the high-salt solid electrolyte film; t2: preparing a solid-state lithium-sulfur battery positive electrode using the method of claim 5; t3: and jointly assembling the positive electrode of the solid lithium-sulfur battery, the high-salt solid electrolyte film and the lithium negative electrode into the solid lithium-sulfur battery.
Preferably, the organic solvent is one of N, N-dimethylformamide, N-methylpyrrolidone, tetrahydrofuran and dimethylsulfoxide.
The invention has the beneficial effects that: the solid lithium sulfur battery anode and the preparation method thereof, and the solid lithium sulfur battery and the preparation method thereof are provided, lithium ions are stored in an organic sulfur material-S-S-bond in a form similar to a lithium iron phosphate anode material embedded lithium storage mode, the reaction energy barrier in the sulfur charging and discharging process is greatly reduced, the volume change is small, and the solid lithium sulfur battery can operate at room temperature and normal pressure.
Drawings
Fig. 1 shows the lithium storage mechanism of the sulfur positive electrode in the solid-state lithium-sulfur battery according to the embodiment of the present invention.
Fig. 2(a) -2 (d) are raman verifications of lithium storage mechanism of the sulfur positive electrode in the solid-state lithium-sulfur battery according to the embodiment of the present invention.
FIG. 3 is a schematic diagram of a process for preparing a positive electrode according to an embodiment of the present invention.
FIG. 4 is a schematic scanning electron microscope of the positive electrode in the embodiment of the invention.
Fig. 5 is a flowchart of the preparation of the solid electrolyte film in the embodiment of the invention.
Fig. 6 is a schematic view of a scanning electron microscope of a solid electrolyte thin film in an example of the present invention.
Fig. 7 is a schematic diagram of a method of manufacturing a solid-state lithium-sulfur battery according to an embodiment of the present invention.
Fig. 8 is a graph showing cycle performance tests performed on a solid-state lithium-sulfur battery according to an example of the present invention.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the embodiments of the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings and the embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or be indirectly connected to the other element. In addition, the connection may be for either a fixing function or a circuit connection function.
It is to be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in an orientation or positional relationship indicated in the drawings for convenience in describing the embodiments of the present invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed in a particular orientation, and be in any way limiting of the present invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the embodiments of the present invention, "a plurality" means two or more unless specifically limited otherwise.
The invention provides a solid-state lithium-sulfur battery anode, which comprises an anode material conductive current collector and a coating material coated on the anode material conductive current collector, wherein the coating material comprises an organic sulfur material, a high-salt solid electrolyte and a conductive agent, and the high-salt solid electrolyte comprises a lithium salt and a high polymer material; wherein at least part of the lithium ions are stored in the-S-bonds of the organosulfur material.
In the anode, similar to the lithium-intercalation energy storage mechanism of the traditional anode material lithium iron phosphate, lithium ions are intercalated into a-S-S-bond on an organic sulfur material to replace the solid-solid conversion of sulfur in the traditional solid lithium-sulfur battery, and the reaction energy barrier is greatly reduced, so that a solid lithium-sulfur system consisting of the anode can have good cycle performance.
Fig. 1 shows the lithium storage mechanism of the sulfur positive electrode in the solid-state lithium-sulfur battery according to the embodiment of the present invention.
As shown in fig. 2(a) -2 (d), the lithium insertion mechanism of the positive electrode can be demonstrated by in-situ raman. FIGS. 2(a) and 2(b) are the Raman signal changes during the discharge and charge of the solid-state lithium-sulfur battery, respectively, from which the Raman peaks (298 and 370 cm) of the-C-S-bond in the sulfurized polyacrylonitrile can be seen-1) There is always lithium sulfide present, indicating that lithium ions enter the-S-bond in intercalated form, rather than opening the-C-S-bond, forming a solid phase. In contrast, as shown in fig. 2(C) and 2(d), for the conventional polyacrylonitrile sulfide-based liquid lithium-sulfur battery, the-C — S-bond disappears during discharging and charging, indicating that the reaction generates solid-phase lithium sulfide and the reaction kinetics are therefore higher.
As shown in fig. 3, a method for preparing a positive electrode of a solid-state lithium-sulfur battery according to a preferred embodiment of the present invention includes the following steps:
s1: dissolving lithium salt and a high polymer material in an organic solvent, and stirring to obtain a high-salt solid electrolyte solution;
s2: grinding an organic sulfur material and a conductive agent, adding the high-salt solid electrolyte solution, and continuously stirring until positive electrode slurry is obtained;
s3: coating the positive electrode slurry on a conductive current collector of a positive electrode material, and removing an organic solvent to obtain the positive electrode;
wherein at least part of the lithium ions are stored in the-S-bonds of the organosulfur material.
In step S1, dissolving lithium salt and a high molecular material in an organic solvent, and stirring at 80 ℃ for 2 hours to obtain a high-salt solid electrolyte solution;
step S2, grinding organic sulfur material and conductive agent for 20min, adding high-salt solid electrolyte solution, and stirring overnight;
and step S3, coating the positive electrode slurry on a two-dimensional current collector aluminum foil, standing overnight at 60 ℃, and removing the organic solvent to obtain the positive electrode.
In one embodiment of the present invention, the positive electrode material conductive current collector may be a two-dimensional current collector aluminum foil or a three-dimensional current collector carbon cloth carbon paper.
Still further, in step S1, the lithium salt in the high-salt solid electrolyte includes LiFSI, LiTFSI, LiClO4At least one of (1); the high molecular material is at least one of polyvinylidene fluoride (PVDF), poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and Polyacrylonitrile (PAN); the organic solvent is one of N, N-dimethylformamide, N-methylpyrrolidone, tetrahydrofuran and dimethyl sulfoxide. The mass fraction of lithium salt in the high-salt solid electrolyte in the organic solvent is 0.1-0.3g/mL, the mass fraction of the high polymer material in the organic solvent is 0.1-0.3g/mL, the mass ratio of the lithium salt to the high polymer material in the high-salt solid electrolyte is 1:1, and the slurry is heated and stirred for 2 hours at the temperature of 80 ℃ on a heating table to completely dissolve the high polymer material.
In step S2, sulfur in the organic sulfur material is grafted on the organic polymer material in the form of covalent bond; the organic polymer material is polyacrylonitrile, dimethyl trisulfide, diphenyl trisulfide or diphenyl tetrasulfide; the conductive agent at least comprises carbon nano tubes, graphene, acetylene black and the like, and organic sulfur materials and the conductive agent are mixed according to the ratio of 1-4:1-4 for 20min, and then adding the high-salt solid electrolyte solution obtained in step S1 so that the organic sulfur material: conductive agent: the high-salt solid electrolyte ratio is 1-4:1-4:1-4, and the positive electrode slurry is stirred at room temperature overnight.
In step S3, the positive electrode slurry is coated on a current collector aluminum foil, heated at 60 ℃ overnight, and the organic solvent is dried.
The positive electrode prepared by the above method is specifically described below with reference to examples for the preparation of a positive electrode material.
Example 1
In a glove box filled with argon, 0.5g of PVDF-HFP and 0.5g of LiFSI were added to 5ml of DMF solvent and stirred magnetically at 80 ℃ for 2 hours to obtain a first dispersion. Grinding 40mg of polyacrylonitrile sulfide and 20mg of carbon nanotubes for 20min, adding 200ul of the first dispersion and 600ul of DMF, and stirring with magnetons at room temperature overnight to obtain positive electrode slurry, wherein the polyacrylonitrile sulfide in the positive electrode slurry: carbon nanotube: high salt solid electrolyte 4:2: 4. And then coating the slurry on a current collector aluminum foil, heating at 60 ℃ overnight, and removing the organic solvent. And punching a current collector aluminum foil coated with the positive electrode material by using a punch with the thickness of 12mm to obtain the sulfur positive electrode plate.
In this embodiment, the mass fraction of the lithium salt in the solid electrolyte may be 0.1g/mL, and the mass fraction of the polymer material may be 0.1 g/mL; or the mass fraction of the lithium salt can be 0.2g/mL, and the mass fraction of the high polymer material can be 0.2 g/mL; or the mass fraction of the lithium salt can be 0.3g/mL, and the mass fraction of the high polymer material can be 0.3 g/mL; it is understood that in other embodiments, the mass fraction of the lithium salt and the mass fraction of the polymeric material may be different, as long as the mass fraction is 0.1-0.3 g/mL.
Example 2
The difference from example 1 is: and (2) vulcanized polyacrylonitrile: carbon nanotube: high salt solid electrolyte 2:1: 1.
Other steps are the same as embodiment 1 and are not described herein.
Example 3
The difference from example 1 is: milling 10mg of polyacrylonitrile sulfide and 40mg of carbon nanotubes for 20min, polyacrylonitrile sulfide: carbon nanotube: high salt solid electrolyte 1:4: 2.
Other steps are the same as embodiment 1 and are not described herein.
As shown in fig. 4, which is a schematic view of the scanning electron microscope of the positive electrode prepared in example 1, it can be seen that the organic sulfur material, the conductive agent, and the high-salt solid electrolyte are uniformly distributed.
As shown in fig. 5, a method for preparing a solid electrolyte film in a solid lithium-sulfur battery according to a preferred embodiment of the present invention includes the following steps:
step S4, dissolving lithium salt and a high polymer material in an organic solvent, wherein the mass of the lithium salt is more than or equal to that of the high polymer material, and stirring for 2h at 80 ℃;
in one embodiment, the ratio of lithium salt to polymeric material is 1-2: 1.
And step S5, coating the slurry on a glass plate, heating the glass plate for 48 hours in vacuum at the temperature of 60 ℃, and removing the organic solvent.
In step S4, the lithium salt in the solid electrolyte film is LiFSI, LiTFSI, LiClO4At least one of (a) and (b); the high polymer material is at least one of PVDF, PVDF-HFP and PAN; the concentration of the lithium salt is 0.1-0.3g/mL, and the concentration of the high molecular material is 0.1-0.3 g/mL; the slurry was stirred on a heating table at 80 ℃ for 2 h.
In step S5, the solution obtained in step S4 was drawn down on a glass plate, heated in vacuo at 60 ℃ for 48h, and the organic solvent was removed.
The preparation of the solid electrolyte film is specifically described below by way of examples.
Example 4
In a glove box filled with argon, the ratio of lithium salt to polymeric material was 1:1, 0.6g of PVDF-HFP and 0.6g of LiFSI were added to 4mL of DMF solvent, and the mixture was stirred magnetically at 80 ℃ for 2h to obtain a second dispersion. And (3) blade-coating the second dispersion liquid on a glass plate, heating for 2h at the temperature of 60 ℃, then vacuumizing, and continuously heating for 48h at the temperature of 60 ℃ to obtain the solid electrolyte film. The solid electrolyte thin film was punched with a 19mm punch to obtain a solid electrolyte thin film sheet.
In this embodiment, the mass fraction of the lithium salt in the solid electrolyte film may be 0.1g/mL, and the mass fraction of the polymer material may be 0.1 g/mL; or the mass fraction of the lithium salt can be 0.2g/mL, and the mass fraction of the high polymer material can be 0.2 g/mL; or the mass fraction of the lithium salt can be 0.3g/mL, and the mass fraction of the high polymer material can be 0.3 g/mL; it is understood that in other embodiments, the mass fraction of the lithium salt and the mass fraction of the polymeric material may be different, as long as the mass fraction is 0.1-0.3 g/mL.
Further, the mass fractions of the lithium salt and the polymer material in the solid electrolyte and the solid electrolyte film in the preparation of the positive electrode may be the same or different. Example 5
The difference from example 4 is: the ratio of lithium salt to polymeric material was 2:1, 0.3g of PVDF-HFP and 0.6g of LiFSI were added to 4mL of DMF solvent.
Other steps are the same as embodiment 4 and are not described herein.
Fig. 6 is a schematic view of the solid electrolyte thin film prepared in example 4 under a light scanning electron microscope, in which it can be seen that the polymer material is uniformly dispersed in the thin film to form a continuous ion-conducting network.
As shown in fig. 7, the present invention also provides a method for preparing a solid-state lithium-sulfur battery comprising a solid electrolyte film and a positive electrode and a lithium negative electrode; the method comprises the following steps:
t1: preparing a high-salt solid electrolyte film: mixing lithium salt, a high polymer material and an organic solvent, coating the mixture on a glass plate by scraping, and removing the organic solvent to obtain the high-salt solid electrolyte film;
t2: preparing a positive electrode by using the method described in S1-S3;
t3: and jointly assembling the positive electrode, the high-salt solid electrolyte film and the lithium negative electrode into a solid lithium-sulfur battery.
The positive electrode sheet prepared in example 1, the solid electrolyte thin film sheets prepared in examples 2 and 3 were assembled into a button cell in an argon-filled glove box in the following order: the lithium battery comprises a negative electrode shell, an elastic sheet, a gasket, a lithium sheet, the solid electrolyte thin membrane, the positive electrode sheet and a positive electrode shell. The subsequent positive electrode shell is arranged at the lower part, and the negative electrode shell is arranged at the upper part and is compacted by a button cell sealing machine for subsequent testing.
Referring to fig. 8, a cycle performance test is performed on a battery assembled by the positive electrode prepared in example 1 and the solid electrolyte film prepared in example 2, according to the present invention, the charge and discharge current density is 0.2C, the cycle number is 100 cycles, and the voltage interval is 1-3V, and compared with other solid lithium sulfur batteries, the battery attenuation is small in the whole cycle process, which indicates that the novel solid lithium sulfur battery system has high cycle stability and high coulombic efficiency.
TABLE 1 electrochemical test results
Figure BDA0003547098130000081
The above examples are all tested at normal temperature and pressure, and the high-salt solid electrolyte films used in examples 1, 2 and 3 are all prepared in example 4; examples 4 and 5 the positive electrode sheets used were each prepared in example 1.
Since the first cycle of the organosulfur material had irreversible capacity, the capacity retention rate was calculated from the second cycle of the discharge capacity. Table 1 shows that the cycle stability at normal temperature and normal pressure can be achieved by the method for preparing the positive electrode and the method for preparing the solid electrolyte film provided by the present invention, and the ionic-electronic conductive network in the positive electrode material can be controlled by different preparation parameters (e.g., the ratio of the organic sulfur material in the positive electrode sheet to the conductive agent to the high-salt solid electrolyte and the ratio of the lithium salt in the high-salt solid electrolyte film to the high-molecular material), so as to affect the electrochemical performance of the solid lithium-sulfur battery.
In the solid-state lithium-sulfur battery provided by the invention, lithium ions can be stored in an organic sulfur material in a form similar to the manner that lithium iron phosphate serving as a positive electrode material is embedded into lithium, so that the reaction energy barrier in the charging and discharging processes of sulfur is greatly reduced, the volume change is small, and a solid-state lithium-sulfur system can operate at room temperature and normal pressure.
In the conventional solid-state lithium-sulfur battery, sulfur is a solid-solid conversion reaction during charge and discharge, and solid-phase sulfur and solid-phase lithium sulfide (Li)2S) is very slow, so normal operation of solid-state lithium-sulfur batteries often requires high temperatures and pressures. In the solid-state lithium-sulfur battery provided by the inventionThe lithium ions are stored in an organic sulfur material-S-S-bond in a form similar to the lithium iron phosphate positive electrode material embedded lithium storage mode, the reaction energy barrier in the sulfur charging and discharging process is greatly reduced, the volume change is small, and the solid lithium sulfur battery can operate at room temperature and normal pressure.
The methods disclosed in the several method embodiments provided in the present application may be combined arbitrarily without conflict to obtain new method embodiments.
Features disclosed in several of the product embodiments provided in the present application may be combined in any combination to yield new product embodiments without conflict.
The features disclosed in the several method or apparatus embodiments provided in the present application may be combined arbitrarily, without conflict, to arrive at new method embodiments or apparatus embodiments.
The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several equivalent substitutions or obvious modifications can be made without departing from the spirit of the invention, and all the properties or uses are considered to be within the scope of the invention.

Claims (10)

1. The positive electrode of the solid-state lithium-sulfur battery is characterized by comprising a positive electrode material conductive current collector and a coating material coated on the positive electrode material conductive current collector, wherein the coating material comprises an organic sulfur material, a high-salt solid electrolyte and a conductive agent, and the high-salt solid electrolyte comprises a lithium salt and a high polymer material; wherein at least part of the lithium ions are stored in the-S-bonds of the organosulfur material.
2. The solid-state lithium sulfur battery positive electrode of claim 1, wherein sulfur in said organosulfur material is covalently grafted to an organic polymeric material.
3. The solid-state lithium sulfur battery positive electrode according to claim 2, wherein the organic polymer material is polyacrylonitrile, dimethyl trisulfide, diphenyl trisulfide or diphenyl tetrasulfide.
4. The solid state lithium sulfur battery positive electrode of claim 3, wherein said lithium salt is LiFSI, LiTFSI, LiClO4At least one of (1);
the high polymer material is at least one of polyvinylidene fluoride, poly (vinylidene fluoride-co-hexafluoropropylene) and polyacrylonitrile;
the mass ratio of the lithium salt to the high polymer material is 1: 1;
the mass ratio of the organic sulfur material, the high-salt solid electrolyte and the conductive agent is 1-4:1-4: 1-4.
5. A method for preparing a solid-state lithium-sulfur battery positive electrode, which is used for preparing the solid-state lithium-sulfur battery positive electrode according to any one of claims 1 to 4, comprising the steps of:
s1: dissolving lithium salt and a high polymer material in an organic solvent, and stirring to obtain a high-salt solid electrolyte solution;
s2: grinding an organic sulfur material and a conductive agent, adding the high-salt solid electrolyte solution, and continuously stirring until positive electrode slurry is obtained;
s3: coating the positive electrode slurry on a conductive current collector of a positive electrode material, and removing an organic solvent to obtain the positive electrode;
wherein at least part of the lithium ions are stored in the-S-bonds of the organosulfur material.
6. A solid-state lithium-sulfur battery comprising a solid electrolyte film, a positive electrode according to any one of claims 1 to 4, and a lithium negative electrode;
the solid electrolyte film comprises lithium salt and a high polymer material.
7. The solid state lithium sulfur battery of claim 6 wherein said lithium salt in said solid state electrolyte film is LiFSI,LiTFSI、LiClO4At least one of (1);
the high polymer material is at least one of polyvinylidene fluoride, poly (vinylidene fluoride-co-hexafluoropropylene) and polyacrylonitrile;
the mass of the lithium salt of the solid electrolyte film is greater than or equal to that of the high polymer material.
8. The solid-state lithium sulfur battery of claim 7 wherein the concentration of lithium salt is 0.1 to 0.3g/mL and the concentration of said polymeric material is 0.1 to 0.3 g/mL.
9. A preparation method of a solid-state lithium-sulfur battery is characterized by comprising the following steps:
t1: preparing a high-salt solid electrolyte film: mixing lithium salt, a high polymer material and an organic solvent, coating the mixture on a glass plate by scraping, and removing the organic solvent to obtain the high-salt solid electrolyte film;
t2: preparing a solid-state lithium-sulfur battery positive electrode using the method of claim 5;
t3: and jointly assembling the positive electrode of the solid lithium-sulfur battery, the high-salt solid electrolyte film and the lithium negative electrode into the solid lithium-sulfur battery.
10. The method of claim 9, wherein the organic solvent is one of N, N-dimethylformamide, N-methylpyrrolidone, tetrahydrofuran, and dimethylsulfoxide.
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