CN115692822A - Method for generating high-activity S-Se/Te bonds to improve performance of lithium-sulfur battery - Google Patents

Method for generating high-activity S-Se/Te bonds to improve performance of lithium-sulfur battery Download PDF

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CN115692822A
CN115692822A CN202110827262.5A CN202110827262A CN115692822A CN 115692822 A CN115692822 A CN 115692822A CN 202110827262 A CN202110827262 A CN 202110827262A CN 115692822 A CN115692822 A CN 115692822A
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electrolyte
lithium
polyacrylonitrile
telluride
sulfur
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谢佳
张薇
吴强
程时杰
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Huazhong University of Science and Technology
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Huazhong University of Science and Technology
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Abstract

The present invention belongs to the field of lithium-sulfur batteries, and more particularly, to a method of generating a highly active S-Se/Te bond to improve the performance of a lithium-sulfur battery. In the method, a soluble organic selenium/telluride additive is added into the electrolyte of the lithium-sulfur battery, so that on one hand, the additive can form an S-Se or S-Te bond with higher electrochemical activity in the charging and discharging processes, and the performance of the polyacrylonitrile sulfide positive electrode is improved; on the other hand, the organic selenium/telluride has electrochemical activity, can contribute to capacity, and further improves the capacity of the sulfur anode. In the method, a very small amount of organic selenium/telluride is introduced to form an S-Se or S-Te bond with high electrochemical activity in the charging and discharging processes of the lithium-sulfur battery, so that the dynamics of a polyacrylonitrile sulfide positive electrode is greatly improved, and the cycle rate performance of the battery is remarkably improved in ether-based and ester-based electrolytes. The invention greatly improves the performance of the lithium-sulfur battery by means of high efficiency, low cost and simple and convenient operation.

Description

Method for generating high-activity S-Se/Te bonds to improve performance of lithium-sulfur battery
Technical Field
The present invention belongs to the field of lithium sulfur batteries, and more particularly, to a method of generating highly active S-Se/Te bonds to improve the performance of a lithium sulfur battery.
Background
With the rapid development of portable electronic products, electric vehicles and large-scale energy storage, people have higher and higher requirements on energy density of batteries. Currently, conventional lithium ion battery systems based on embedded electrodes (e.g., liMnO) 2 、LiFePO 4 、LiCoO 2 ) The development demand for high energy density has not been met. In the new generation of energy storage battery systems, lithium-sulfur batteries based on multiple electron conversion reactions and light elements are due to their ultra-high theoretical energy density (2600 Wh kg) -1 ) Low material price, and excellent environmental friendliness, are considered to be one of the most promising new secondary battery systems.
However, the practical lithium sulfur full cell still has great technical problems, which hinder the commercialization process thereof. For example: the electronic insulation of sulfur; the lithium-sulfur battery has poor performance in the aspects of energy density, cycle stability and the like due to large volume expansion in the charging and discharging process, shuttle effect of the intermediate product lithium polysulfide between the positive electrode and the negative electrode and the like. The polyacrylonitrile sulfide is an organic sulfur molecule with a conductive polymer skeleton structure, and has a certain buffer effect on volume expansion in the charge-discharge process; more importantly, the special molecular structure of the electrolyte enables the electrolyte to have no obvious polysulfide dissolution phenomenon in the carbonate electrolyte. However, as with the conventional carbon-sulfur material, the kinetics of polyacrylonitrile sulfide is still slow, resulting in poor cycle rate performance. Therefore, it is important to improve the reaction kinetics of the polyacrylonitrile sulfide positive electrode and effectively suppress polysulfide elution to exert the performance of the battery. At present, the dynamics of sulfur conversion reaction can be improved to a certain extent by designing a composite nano-structure anode, a functional diaphragm and the like, polysulfide dissolution is inhibited, and the utilization rate of active substances is improved.
In reported literature (nat. Commun.,2019,10 (1), 1021 electrochemical Energy reviews,2020,3,613-642 Nano Energy,2019,60, 153-161), the generation of S-Se bond and S-Te bond is found to be effective in inhibiting polysulfide shuttling effect and greatly improving sulfur anode kinetics. However, these methods produce S-Se/Te bonds by solid phase ball milling of sulfur powder, selenium/tellurium powder, and high temperature sintering to produce Se or Te doped sulfur anodes. Obviously, the preparation method thereof is complicated and time-consuming, greatly increasing the manufacturing cost of the lithium sulfur battery.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a simple and efficient method for quickly generating S-Se/Te bonds with high electrochemical activity so as to greatly improve the sulfur conversion reaction kinetics and further improve the performance of a lithium-sulfur battery, and aims to solve the technical problems that the S-Se/Te bonds generated in the lithium-sulfur battery in the prior art are low in activity, so that the sulfur conversion kinetics are not obviously improved, and further the cycle rate performance of the lithium-sulfur battery is poor.
To achieve the above objects, the present invention provides a method of generating a highly active S-Se/Te bond to improve the performance of a lithium sulfur battery by adding a soluble organic selenide additive and/or an organic telluride additive to an electrolyte of the lithium sulfur battery.
Preferably, the method comprises the following steps:
(1) Adding soluble organic selenium compound and/or organic telluride as an additive into a blank ether or ester electrolyte to obtain an organic selenium/telluride electrolyte;
(2) And (2) assembling a polyacrylonitrile sulfide electrode serving as a positive electrode and a lithium sheet serving as a negative electrode by using a diaphragm and the organic selenium/telluride electrolyte in the step (1) to obtain the lithium-sulfur battery.
Preferably, the soluble organic selenide additive is selected from diphenyl diselenide, diphenyl triselenide and diphenyl tetraselenide, and the soluble organic telluride additive is selected from diphenyl diantimony ether, diphenyl diantimony ether and diphenyl tetratimony ether.
Preferably, the molar ratio of the sulfur element in the sulfurized polyacrylonitrile electrode to Se/Te in the soluble organic selenium compound and/or organic telluride is 4-25.
Preferably, the blank ether electrolyte is prepared by mixing lithium bistrifluoromethanesulfonylimide and LiNO 3 And the electrolyte is obtained by dissolving the electrolyte in a mixed solution of 1,3-dioxolane and ethylene glycol dimethyl ether.
Preferably, the blank ester electrolyte is obtained by dissolving lithium hexafluorophosphate and fluoroethylene carbonate in a mixed solution of ethylene carbonate and diethyl carbonate.
Preferably, the area sulfur-carrying amount in the sulfurized polyacrylonitrile electrode is 0.5-3mg/cm 2 。
Preferably, the preparation method of the sulfurized polyacrylonitrile electrode comprises the following steps:
(1) Uniformly mixing sulfur powder and polyacrylonitrile, and reacting at 250-450 ℃ for 2.5-5h in an argon atmosphere to obtain a vulcanized polyacrylonitrile material;
(2) And uniformly mixing the prepared polyacrylonitrile sulfide material with a conductive agent and a binder, taking water as a solvent to prepare anode slurry, coating the anode slurry on a current collector, drying and stamping to obtain the polyacrylonitrile sulfide anode piece.
According to another aspect of the present invention, there is provided a method of manufacturing a lithium sulfur battery, including the steps of:
(1) Adding a soluble organic selenide additive and/or an organic telluride as an additive into a blank ether or ester electrolyte to obtain an organic selenium/telluride electrolyte;
(2) And (2) assembling a polyacrylonitrile sulfide electrode serving as a positive electrode and a lithium sheet serving as a negative electrode by using a diaphragm and the organic selenium/telluride electrolyte in the step (1) to obtain the lithium-sulfur battery.
According to another aspect of the present invention, there is provided a lithium sulfur battery comprising a positive electrode, a negative electrode, an electrolyte, and a separator; the positive electrode is a polyacrylonitrile sulfide electrode, the negative electrode is a lithium sheet, the electrolyte is a blank ether electrolyte or a blank ester electrolyte, and soluble organic selenide and/or soluble organic telluride are added in the electrolyte; the diaphragm is a polypropylene diaphragm.
Generally, compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects:
(1) The invention provides a method for generating high-activity S-Se/Te bonds to improve the performance of a lithium-sulfur battery, which selects soluble organic selenium/telluride as an additive of electrolyte, and on one hand, the soluble organic selenium/telluride can form the high-electrochemical-activity S-Se/S-Te bonds in the charging and discharging processes, thereby greatly improving the battery performance of a vulcanized polyacrylonitrile anode; on the other hand, the organic selenium/telluride has electrochemical activity and can contribute to capacity, so that the capacity of the sulfur anode is further improved.
(2) The positive electrode of the lithium-sulfur battery adopts vulcanized polyacrylonitrile (S @ pPAN) with a conductive polymer skeleton structure, and has a certain buffer effect on volume expansion in the charging and discharging processes; more importantly, the special molecular structure of the electrolyte enables the electrolyte to have no obvious polysulfide dissolution phenomenon in the carbonate electrolyte.
(3) The introduction of a small amount of organic selenium/telluride in the electrolyte of the lithium-sulfur battery forms an S-Se/Te bond with higher electrochemical activity through radical exchange in the charging and discharging processes, thereby greatly accelerating the sulfur conversion kinetics and further improving the battery performance of the polyacrylonitrile sulfide anode.
(4) According to the lithium-sulfur battery provided by the preferred embodiment of the invention, a very small amount of soluble organic selenium/telluride is introduced into blank ether or ester electrolyte, and acrylonitrile sulfide composite material is adopted as a positive electrode material, so that S-Se or S-Te bonds with higher electrochemical activity are formed in the charging and discharging processes, the dynamics of a polyacrylonitrile sulfide positive electrode is greatly improved, and the cycling rate performance of the lithium-sulfur battery is prepared in ether and ester electrolyte. Particularly in ester electrolyte, the obtained lithium-sulfur battery shows 1385.3mAh g at 1C current density -1 The second round reversible capacity of (c). Therefore, the invention greatly improves the performance of the lithium-sulfur battery in a mode of high efficiency, low cost and simple and convenient operation.
Drawings
Fig. 1 is a graph of cycle performance of ester electrolytes with different contents of organic selenides added in reference example 1 and embodiment examples 1-3.
Fig. 2 is raman spectra before and after the anode cycle in which the organic selenide electrolyte was added in reference example 1 and example 2.
Fig. 3 is a graph of battery rate performance of the ester electrolyte added with the organic selenide in reference example 1 and embodiment example 2.
Fig. 4 is a graph of cycle performance at a current density of 0.5C for the batteries of ether electrolyte added with organic selenide in reference example 2 and example 5.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention.
The method for simply and efficiently generating the high-activity S-Se/Te bond to improve the performance of the lithium-sulfur battery, provided by the invention, is characterized in that a soluble organic selenide additive and/or an organic telluride additive are added into the electrolyte of the lithium-sulfur battery.
The "/" in the "S-Se/Te bond", "organoselenium/telluride", "Se/Te in organoselenium/telluride" and the like in the present invention means "and/or". When a soluble organic selenide additive is added into the electrolyte of the lithium-sulfur battery, high-activity S-Se bonds are correspondingly generated; when a soluble organic telluride additive is added into the electrolyte of the lithium-sulfur battery, high-activity S-Te bonds are correspondingly generated; when the soluble organic selenide additive and the organic telluride additive are simultaneously added into the electrolyte of the lithium-sulfur battery, high-activity S-Se bonds and S-Te bonds are correspondingly and simultaneously generated.
In some embodiments, the method comprises the steps of:
(1) Adding soluble organic selenium/telluride as an additive into a blank ether or ester electrolyte to obtain an organic selenium/telluride electrolyte;
(2) And (2) assembling a polyacrylonitrile sulfide electrode serving as a positive electrode and a lithium sheet serving as a negative electrode by using a diaphragm and the organic selenium/telluride electrolyte in the step (1) to obtain the lithium-sulfur battery.
In some embodiments, the soluble organic selenide additive is selected from diphenyl diselenide, diphenyl triselenide, and diphenyl tetraselenide, and the soluble organic telluride additive is selected from diphenyl diantimony ether, and diphenyl tetrastibony ether.
In some embodiments, the molar ratio of elemental sulfur in the sulfurized polyacrylonitrile electrode to Se/Te in the soluble organoselenium/tellurium compound is 4 to 25. When a soluble organic selenide additive is added into the electrolyte of the lithium-sulfur battery, high-activity S-Se bonds are correspondingly generated, and the molar ratio of sulfur element in a sulfurized polyacrylonitrile electrode to Se in the soluble organic selenide is 4-25; when a soluble organic telluride additive is added into the electrolyte of the lithium-sulfur battery, high-activity S-Te bonds are correspondingly generated, and the molar ratio of sulfur element in the sulfurized polyacrylonitrile electrode to Te in the soluble organic telluride is 4-25; when the soluble organic selenide additive and the organic telluride additive are added into the electrolyte of the lithium-sulfur battery at the same time, high-activity S-Se bonds and S-Te bonds are correspondingly generated, and the molar ratio of sulfur element in the sulfurized polyacrylonitrile electrode to the total amount of Se and Te in the soluble organic selenium/telluride is 4-25.
In some embodiments, the blank ether electrolyte is a mixture of lithium bistrifluoromethanesulfonylimide (LiTFSI) and LiNO 3 And an electrolyte obtained by dissolving the electrolyte in a mixed solution of 1,3-Dioxolane (DOL) and ethylene glycol dimethyl ether (DME).
In some embodiments, the blank ether electrolyte is obtained by: lithium bistrifluoromethanesulfonylimide (LiTFSI) and LiNO 3 Dissolving in a mixed solution of 1,3-Dioxolane (DOL) and ethylene glycol dimethyl ether (DME), and fully stirring to obtain blank ether electrolyte; the volume ratio of 1,3-dioxolane to ethylene glycol dimethyl ether in the mixed solution is 1:1; the concentration of the lithium bistrifluoromethanesulfonylimide is 1M 3 The concentration was 0.2M.
In some embodiments, the blankThe ester electrolyte is prepared by mixing lithium hexafluorophosphate (LiPF) 6 ) And an electrolytic solution obtained by dissolving fluoroethylene carbonate (FEC) in a mixed solution of Ethylene Carbonate (EC) and diethyl carbonate (DEC).
In some embodiments, the blank ester electrolyte is obtained by: mixing lithium hexafluorophosphate (LiPF) 6 ) Dissolving fluoroethylene carbonate (FEC) in a mixed solution of Ethylene Carbonate (EC) and diethyl carbonate (DEC), and fully stirring to obtain a blank ester electrolyte; the volume ratio of the Ethylene Carbonate (EC), the diethyl carbonate (DEC) and the fluoroethylene carbonate (FEC) in the mixed solution is 4.5; the lithium hexafluorophosphate (LiPF) 6 ) The concentration was 1M.
In some embodiments, the area sulfur loading of the sulfurized polyacrylonitrile electrode is 0.5-3mg/cm 2 。
In some embodiments, the preparation method of the sulfurized polyacrylonitrile electrode comprises the following steps:
(1) Uniformly mixing sulfur powder and polyacrylonitrile, and reacting at 250-450 ℃ for 2.5-5h under the atmosphere of argon to obtain a vulcanized polyacrylonitrile material;
(2) And uniformly mixing the prepared polyacrylonitrile sulfide material with a conductive agent and a binder, taking water as a solvent to prepare anode slurry, coating the anode slurry on a current collector, drying and stamping to obtain the polyacrylonitrile sulfide anode piece.
In some embodiments, the sulfurized polyacrylonitrile electrode is obtained by: uniformly grinding sulfur powder and polyacrylonitrile with the mass ratio of 3:1, and reacting for 3 hours at 300 ℃ in a high-temperature tube furnace in an argon atmosphere to obtain the vulcanized polyacrylonitrile material. Then, the prepared polyacrylonitrile sulfide, a conductive agent Keqin Black (KB) and a binder are uniformly mixed according to the mass ratio of 7. Preparing anode slurry on a high-speed dispersion machine by using water as a solvent, coating the anode slurry on a carbon-coated aluminum foil current collector by using a coating machine, fixing the carbon-coated aluminum foil current collector on a flat glass plate, drying in a vacuum drying box, and stamping to obtain a vulcanized polyacrylonitrile anode plate, wherein the area sulfur-carrying amount is 0.5-3mg/cm 2 。
The invention also provides a preparation method of the lithium-sulfur battery, which comprises the following steps:
(1) Adding soluble organic selenium/telluride as an additive into a blank ether or ester electrolyte to obtain an organic selenium/telluride electrolyte;
(2) And (2) assembling a polyacrylonitrile sulfide electrode serving as a positive electrode and a lithium sheet serving as a negative electrode by using a diaphragm and the organic selenium/telluride electrolyte in the step (1) to obtain the lithium-sulfur battery.
The invention also provides a lithium-sulfur battery, which comprises a positive electrode, a negative electrode, electrolyte and a diaphragm; the positive electrode is a polyacrylonitrile sulfide electrode, the negative electrode is a lithium sheet, the electrolyte is a blank ether electrolyte or a blank ester electrolyte, and soluble organic selenium/telluride is added in the electrolyte; the membrane was a commercial polypropylene membrane.
The invention provides a novel method for generating S-Se/Te bonds with higher electrochemical activity to accelerate sulfur conversion kinetics, soluble organic selenium/telluride is used as an additive to be added into blank ether or ester electrolyte, and the organic selenium/telluride electrolyte with certain mass fraction is obtained after full stirring; assembling a button cell by adopting a polyacrylonitrile sulfide electrode as a positive electrode, a lithium sheet as a negative electrode, commercial polypropylene as a diaphragm and organic selenium/telluride electrolyte; and after standing for 12 hours, performing charge-discharge cycle test on the battery by using a multi-channel battery tester. The cell assembly was made in an argon atmosphere glove box, with both oxygen and water values less than 0.01ppm.
In some embodiments, assembling a conventional battery is specifically: the polyacrylonitrile sulfide composite electrode is used as a positive electrode, a lithium sheet with the thickness of 400um is used as a negative electrode, commercial polypropylene is used as a diaphragm, and the polyacrylonitrile sulfide composite electrode and 30uL of organic selenium/telluride electrolyte containing different mass fractions are arranged in a 2032 button battery case together.
In the method provided by the invention, the organic selenium/telluride is directly used as the electrolyte additive and is introduced into the lithium-sulfur battery based on the polyacrylonitrile sulfide anode, so that the battery performance of the polyacrylonitrile sulfide anode can be greatly improved. The invention has the beneficial effects that: 1) The positive electrode adopts vulcanized polyacrylonitrile with a conductive polymer skeleton structure, so that volume expansion can be relieved in the charging and discharging processes; and no obvious polysulfide shuttling effect appears in the carbonate electrolyte; 2) The introduction of a very small amount of organic selenium/telluride can form S-Se or S-Te bonds with higher electrochemical activity in the charging and discharging processes, thereby greatly improving the dynamics of the polyacrylonitrile sulfide anode and obviously improving the cycle rate performance of the battery in ether-based and ester-based electrolyte. Therefore, the invention greatly improves the performance of the lithium-sulfur battery in a mode of high efficiency, low cost and simple and convenient operation.
The following are specific examples:
reference case
(1) Preparation of Ether electrolyte
1M lithium bistrifluoromethanesulfonimide (LiTFSI) and 0.2M LiNO 3 Dissolving in 1L 1,3-Dioxolane (DOL)/ethylene glycol dimethyl ether (DME) (volume ratio of 1:1), and stirring to obtain blank ether electrolyte.
(2) Preparation of ester electrolyte
1M lithium hexafluorophosphate (LiPF) 6 ) The mixture was dissolved in a mixed solution of Ethylene Carbonate (EC), diethyl carbonate (DEC) and fluoroethylene carbonate (FEC) (volume ratio 4.5.
(3) Preparation of cathode material
Uniformly grinding sulfur powder and polyacrylonitrile with the mass ratio of 3:1, and reacting for 3 hours at 300 ℃ in a high-temperature tube furnace in an argon atmosphere to obtain the vulcanized polyacrylonitrile material. Then, the prepared polyacrylonitrile sulfide, a conductive agent Keqin Black (KB) and a binder are uniformly mixed according to the mass ratio of 7. Preparing anode slurry on a high-speed dispersion machine by using water as a solvent, coating the anode slurry on a carbon-coated aluminum foil current collector by using a coating machine, fixing the carbon-coated aluminum foil current collector on a flat glass plate, drying in a vacuum drying box, stamping to obtain a vulcanized polyacrylonitrile anode plate, wherein the area sulfur-carrying amount is 1.5mg/cm 2 Left and right.
(4) Assembly of battery
And (3) taking the vulcanized polyacrylonitrile composite electrode obtained in the third step as a positive electrode, a lithium sheet with the thickness of 400um as a negative electrode and commercial polypropylene as a diaphragm, and filling the diaphragm and 30uL of blank ester electrolyte into a 2032 button battery case. And after standing for 12 hours, performing charge-discharge cycle test by using a multi-channel battery tester. The blank ester electrolyte is obtained by the following method: mixing lithium hexafluorophosphate (LiPF) 6 ) Dissolving fluoroethylene carbonate (FEC) in a mixed solution of Ethylene Carbonate (EC) and diethyl carbonate (DEC), and fully stirring to obtain a blank ester electrolyte; the volume ratio of the Ethylene Carbonate (EC), the diethyl carbonate (DEC) and the fluoroethylene carbonate (FEC) in the mixed solution is 4.5; the lithium hexafluorophosphate (LiPF) 6 ) The concentration was 1M.
Reference example 2
The other steps were the same as reference example 1, except that a blank ether electrolyte was used in assembling the battery in the step (4). The blank ether electrolyte is obtained by the following method: lithium bistrifluoromethanesulfonylimide (LiTFSI) and LiNO 3 Dissolving in a mixed solution of 1,3-Dioxolane (DOL) and ethylene glycol dimethyl ether (DME), and fully stirring to obtain blank ether electrolyte; the volume ratio of 1,3-dioxolane to ethylene glycol dimethyl ether in the mixed solution is 1:1; the concentration of the lithium bistrifluoromethanesulfonylimide is 1M 3 The concentration was 0.2M.
Example 1
(1) Preparation of ester electrolyte
1M lithium hexafluorophosphate (LiPF) 6 ) The mixture was dissolved in a mixed solution of Ethylene Carbonate (EC), diethyl carbonate (DEC) and fluoroethylene carbonate (FEC) (volume ratio 4.5. Then, taking a certain blank electrolyte, adding a certain amount of diphenyl diselenide (PDSE), wherein the molar ratio of S in the sulfurized polyacrylonitrile to Se in the diphenyl diselenide is 15.
(2) Preparation of cathode material
Uniformly grinding sulfur powder and polyacrylonitrile with the mass ratio of 3:1 in a high-temperature tube furnace at 300 ℃ in an argon atmosphereAnd reacting for 3 hours to obtain the vulcanized polyacrylonitrile material. Then, the prepared polyacrylonitrile sulfide, a conductive agent Keqin Black (KB) and a binder are uniformly mixed according to the mass ratio of 7. Preparing anode slurry on a high-speed dispersion machine by using water as a solvent, coating the anode slurry on a carbon-coated aluminum foil current collector by using a coating machine, fixing the carbon-coated aluminum foil current collector on a flat glass plate, drying in a vacuum drying box, stamping to obtain a vulcanized polyacrylonitrile anode plate, wherein the area sulfur-carrying amount is 1.5mg/cm 2 Left and right.
(3) Assembly of battery
And (3) taking the polyacrylonitrile sulfide composite electrode obtained in the third step as a positive electrode, a lithium sheet with the thickness of 400um as a negative electrode and commercial polypropylene as a diaphragm, and filling the polyacrylonitrile sulfide composite electrode and 30uL of diphenyl diselenide electrolyte with different contents into a 2032 button battery case (the molar ratio of S in polyacrylonitrile sulfide to Se in organic selenium/telluride is 15. And (5) after standing for 12 hours, performing charge-discharge cycle test by using a multi-channel battery tester.
Example 2
(1) Preparation of ester electrolyte
1M lithium hexafluorophosphate (LiPF) 6 ) The mixture was dissolved in a mixed solution of Ethylene Carbonate (EC), diethyl carbonate (DEC) and fluoroethylene carbonate (FEC) (volume ratio 4.5. Then, taking a certain amount of blank electrolyte, adding a certain amount of diphenyl diselenide (PDSE), wherein the molar ratio of S in the sulfurized polyacrylonitrile to Se in the diphenyl diselenide is 10.
(2) Preparation of cathode material
Uniformly grinding sulfur powder and polyacrylonitrile with the mass ratio of 3:1, and reacting for 3 hours at 300 ℃ in a high-temperature tube furnace in an argon atmosphere to obtain the vulcanized polyacrylonitrile material. Then, the prepared polyacrylonitrile sulfide, a conductive agent Keqin Black (KB) and a binder are uniformly mixed according to the mass ratio of 7. Using water as solvent, preparing anode slurry on high-speed dispersion machine, and adopting coating processCoating the positive electrode slurry on a carbon-coated aluminum foil current collector by a cloth machine, fixing the carbon-coated aluminum foil current collector on a flat glass plate, drying the carbon-coated aluminum foil current collector in a vacuum drying box, and stamping to obtain a vulcanized polyacrylonitrile positive electrode plate, wherein the sulfur-carrying amount of the area is 1.5mg/cm 2 Left and right.
(3) Assembly of a battery
And (3) taking the polyacrylonitrile sulfide composite electrode obtained in the third step as a positive electrode, a lithium sheet with the thickness of 400um as a negative electrode and commercial polypropylene as a diaphragm, and filling the diaphragm and 30uL of diphenyl diselenide electrolyte with different contents into a 2032 button battery case (the molar ratio of S in polyacrylonitrile sulfide to Se in diphenyl diselenide is 10. And after standing for 12 hours, performing charge-discharge cycle test by using a multi-channel battery tester.
Example 3
(1) Preparation of ester electrolyte
1M lithium hexafluorophosphate (LiPF) 6 ) The mixture was dissolved in a mixed solution of Ethylene Carbonate (EC), diethyl carbonate (DEC) and fluoroethylene carbonate (FEC) (volume ratio 4.5. Then, taking a certain amount of blank electrolyte, adding a certain amount of diphenyl diselenide (PDSE), wherein the molar ratio of S in the sulfurized polyacrylonitrile to Se in the diphenyl diselenide is 5:1, and fully stirring to obtain the electrolyte of S @ pPAN-PDSe-5:1.
(2) Preparation of cathode material
Uniformly grinding sulfur powder and polyacrylonitrile with the mass ratio of 3:1, and reacting for 3 hours at 300 ℃ in a high-temperature tube furnace in an argon atmosphere to obtain the vulcanized polyacrylonitrile material. Then, the prepared polyacrylonitrile sulfide, a conductive agent Keqin Black (KB) and a binder are uniformly mixed according to the mass ratio of 7. Preparing anode slurry on a high-speed dispersion machine by using water as a solvent, coating the anode slurry on a carbon-coated aluminum foil current collector by using a coating machine, fixing the carbon-coated aluminum foil current collector on a flat glass plate, drying in a vacuum drying box, stamping to obtain a vulcanized polyacrylonitrile anode plate, wherein the area sulfur-carrying amount is 1.5mg/cm 2 Left and right.
(3) Assembly of battery
And (3) taking the polyacrylonitrile sulfide composite electrode obtained in the third step as a positive electrode, a lithium sheet with the thickness of 400um as a negative electrode and commercial polypropylene as a diaphragm, and filling the diaphragm and 30uL of diphenyl diselenide electrolyte with different contents into a 2032 button battery case (the molar ratio of S in polyacrylonitrile sulfide to Se in diphenyl diselenide is 5:1). And after standing for 12 hours, performing charge-discharge cycle test by using a multi-channel battery tester.
FIG. 1 is a graph showing the cycle performance at a current density of 1C of batteries in reference example 1 and examples 1 to 3, in which ester electrolytes containing different amounts of organic selenide were added, and it can be seen that the initial discharge capacity was 1712.9mAh g for S @ pPAN batteries in which no organic selenide was added -1 After circulating for 100 circles, the capacity is 929.2mAh g -1 The capacity retention rate was 54.2%. After the organic selenide-containing ester electrolyte is used, the capacity and the cycling stability of the S @ pPAN battery are remarkably improved, particularly when the molar ratio of S in the S @ pPAN to Se in the organic selenide is 10, the optimal cycling performance is shown, and the reversible capacity of the second circle is as high as 1385.3mAh g -1 After circulating for 100 circles, the capacity is still as high as 1135.0mAh g -1 The capacity retention rate was improved to 65.0%.
Fig. 2 is a raman spectrum before and after the anode cycle in reference case 1 and example 2 in which the organic selenide electrolyte was added. It can be seen that the introduction of the organic selenide allows the S @ pPAN electrode to form an S-Se bond during charge and discharge.
Fig. 3 is a battery rate performance diagram of the reference case 1 and the battery added with the organic selenide ester electrolyte in the example 2, and it can be seen that the rate performance of the s @ ppan battery is greatly improved by adding the organic selenide. The capacity of the S @ pPAN battery is 603.9mAh g, especially at a high current density of 5C -1 And the capacity of the S @ pPAN battery added with the organic selenide reaches 1090.9mAh g -1 。
Fig. 4 is a graph of cycle performance at a current density of 0.5C for the batteries of ether electrolyte added with organic selenide in reference example 2 and example 5. It can be seen that the introduction of the organic selenide also greatly improves the cycle performance of the S @ pPAN electrode in the ether electrolyte. After 70 cycles of cycling, the discharge capacity of the S @ pPAN battery rapidly decayed to 574.2mAh g -1 The discharge capacity of the S @ pPAN battery added with the organic selenide can still be maintained at 746.5mAh g -1 。
Example 4
(1) Preparation of Ether electrolyte
1M lithium bistrifluoromethanesulfonimide (LiTFSI) and 0.2M LiNO 3 Dissolving in 1L 1,3-Dioxolane (DOL)/ethylene glycol dimethyl ether (DME) (volume ratio of 1:1), and stirring to obtain blank ether electrolyte. Then, taking a certain amount of blank electrolyte, adding a certain amount of diphenyl diselenide (PDSE), wherein the molar ratio of S in the sulfurized polyacrylonitrile to Se in the organic selenium/telluride is 12.
(2) Preparation of cathode material
Uniformly grinding sulfur powder and polyacrylonitrile in a mass ratio of 3:1, and reacting for 3 hours at 300 ℃ in an argon atmosphere in a high-temperature tube furnace to obtain the vulcanized polyacrylonitrile material. Then, the prepared polyacrylonitrile sulfide, a conductive agent Keqin Black (KB) and a binder are uniformly mixed according to the mass ratio of 7. Preparing anode slurry on a high-speed dispersion machine by using water as a solvent, coating the anode slurry on a carbon-coated aluminum foil current collector by using a coating machine, fixing the carbon-coated aluminum foil current collector on a flat glass plate, drying in a vacuum drying oven, and stamping to obtain a vulcanized polyacrylonitrile anode plate, wherein the area sulfur-carrying amount is 1.5mg/cm 2 Left and right.
(3) Assembly of battery
And (3) taking the polyacrylonitrile sulfide composite electrode obtained in the third step as a positive electrode, a lithium sheet with the thickness of 400um as a negative electrode and commercial polypropylene as a diaphragm, and filling the diaphragm and 30uL of diphenyl diselenide electrolyte with different contents into a 2032 button battery case (the molar ratio of S in polyacrylonitrile sulfide to Se in diphenyl diselenide is 12. And after standing for 12 hours, performing charge-discharge cycle test by using a multi-channel battery tester.
Example 5
(1) Preparation of Ether electrolyte
1M lithium bistrifluoromethanesulfonimide (LiTFSI) and 0.2M LiNO 3 Dissolving in 1L 1,3-Dioxolane (DOL)/ethylene glycol dimethyl ether (DME) (volume ratio of 1:1), and stirring to obtain blank ether electrolyte. Then, a certain amount of diphenyl diselenide (PDSE) is added into a certain blank electrolyte, wherein the molar ratio of S in the polyacrylonitrile sulfide to Se in the organic selenium/telluride is 7:1, and the electrolyte of S @ pPAN-PDSE-7:1 is obtained after full stirring.
(2) Preparation of cathode material
Uniformly grinding sulfur powder and polyacrylonitrile with the mass ratio of 3:1, and reacting for 3 hours at 300 ℃ in a high-temperature tube furnace in an argon atmosphere to obtain the vulcanized polyacrylonitrile material. Then, the prepared polyacrylonitrile sulfide, a conductive agent Keqin Black (KB) and a binder are uniformly mixed according to the mass ratio of 7. Preparing anode slurry on a high-speed dispersion machine by using water as a solvent, coating the anode slurry on a carbon-coated aluminum foil current collector by using a coating machine, fixing the carbon-coated aluminum foil current collector on a flat glass plate, drying in a vacuum drying box, stamping to obtain a vulcanized polyacrylonitrile anode plate, wherein the area sulfur-carrying amount is 1.5mg/cm 2 Left and right.
(3) Assembly of battery
The polyacrylonitrile sulfide composite electrode obtained in the third step is taken as a positive electrode, a lithium sheet with the thickness of 400um is taken as a negative electrode, commercial polypropylene is taken as a diaphragm, and the diaphragm and 30uL of diphenyl diselenide electrolyte with different contents are arranged in a 2032 button battery case (the molar ratio of S in polyacrylonitrile sulfide to Se in organic selenium/telluride is 7:1). And (5) after standing for 12 hours, performing charge-discharge cycle test by using a multi-channel battery tester.
Example 6
(1) Preparation of Ether electrolyte
1M lithium bistrifluoromethanesulfonimide (LiTFSI) and 0.2M LiNO 3 Dissolving in 1L 1,3-Dioxolane (DOL)/ethylene glycol dimethyl ether (DME) (volume ratio of 1:1), and stirring to obtain blank ether electrolyte. Then, a certain amount of diphenyl diselenide (PDSE) is added into a certain amount of blank electrolyte, wherein the molar ratio of S in the sulfurized polyacrylonitrile to Se in the diphenyl diselenide is 4:1, and the mixture is fully stirredThus obtaining an electrolyte solution of S @ pPAN-PDSe-4:1.
(2) Preparation of cathode material
Uniformly grinding sulfur powder and polyacrylonitrile with the mass ratio of 3:1, and reacting for 3 hours at 300 ℃ in a high-temperature tube furnace in an argon atmosphere to obtain the vulcanized polyacrylonitrile material. Then, the prepared polyacrylonitrile sulfide, a conductive agent Keqin Black (KB) and a binder are uniformly mixed according to the mass ratio of 7. Preparing anode slurry on a high-speed dispersion machine by using water as a solvent, coating the anode slurry on a carbon-coated aluminum foil current collector by using a coating machine, fixing the carbon-coated aluminum foil current collector on a flat glass plate, drying in a vacuum drying box, stamping to obtain a vulcanized polyacrylonitrile anode plate, wherein the area sulfur-carrying amount is 1.5mg/cm 2 Left and right.
3) Assembly of battery
And (3) taking the polyacrylonitrile sulfide composite electrode obtained in the third step as a positive electrode, a lithium sheet with the thickness of 400um as a negative electrode and commercial polypropylene as a diaphragm, and filling the diaphragm and 30uL of diphenyl diselenide electrolyte with different contents into a 2032 button battery case (the molar ratio of S in polyacrylonitrile sulfide to Se in diphenyl diselenide is 4:1). And after standing for 12 hours, performing charge-discharge cycle test by using a multi-channel battery tester.
Besides Super P, the conductive agent used in the invention can also adopt other conductive agents, such as Ketjen black, acetylene black and the like, and the corresponding mass ratio is kept unchanged. The raw materials used in the present invention are all commercially available.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims (10)

1. A method of forming highly active S-Se/Te bonds for improving the performance of a lithium sulfur battery, characterized in that a soluble organoselenide additive and/or an organotelluride additive is added to the electrolyte of the lithium sulfur battery.
2. The method of claim 1, comprising the steps of:
(1) Adding soluble organic selenium compound and/or organic telluride as an additive into a blank ether or ester electrolyte to obtain an organic selenium/telluride electrolyte;
(2) And (2) assembling a diaphragm and the organic selenium/telluride electrolyte in the step (1) by taking a polyacrylonitrile sulfide electrode as a positive electrode and a lithium sheet as a negative electrode to obtain the lithium-sulfur battery.
3. The method of claim 1 or 2, wherein the soluble organic selenide additive is selected from the group consisting of diphenyl diselenide, diphenyl triselenide, and diphenyl tetraselenide, and the soluble organic telluride additive is selected from the group consisting of diphenyl diantimony ether, and diphenyl tetratimony ether.
4. The method of claim 2, wherein the molar ratio of elemental sulfur in the sulfurized polyacrylonitrile electrode to Se/Te in the soluble organoselenium compound and/or organotelluride is from 4 to 25.
5. The method according to claim 2, wherein the blank ether electrolyte is lithium bistrifluoromethanesulfonylimide and LiNO 3 And the electrolyte is obtained by dissolving the electrolyte in a mixed solution of 1,3-dioxolane and ethylene glycol dimethyl ether.
6. The method according to claim 2, wherein the blank ester electrolyte is an electrolyte obtained by dissolving lithium hexafluorophosphate and fluoroethylene carbonate in a mixed solution of ethylene carbonate and diethyl carbonate.
7. The method of claim 2, wherein the sulfur is loaded on the area of the polyacrylonitrile sulfide electrode from 0.5 to 3mg/cm 2 。
8. The method of claim 7, wherein the preparation method of the sulfurized polyacrylonitrile electrode comprises the steps of:
(1) Uniformly mixing sulfur powder and polyacrylonitrile, and reacting at 250-450 ℃ for 2.5-5h in an argon atmosphere to obtain a vulcanized polyacrylonitrile material;
(2) And uniformly mixing the prepared polyacrylonitrile sulfide material with a conductive agent and a binder, taking water as a solvent to prepare anode slurry, coating the anode slurry on a current collector, drying and stamping to obtain the polyacrylonitrile sulfide anode piece.
9. A method for preparing a lithium-sulfur battery is characterized by comprising the following steps:
(1) Adding a soluble organic selenide additive and/or an organic telluride as an additive into a blank ether or ester electrolyte to obtain an organic selenium/telluride electrolyte;
(2) And (2) assembling a polyacrylonitrile sulfide electrode serving as a positive electrode and a lithium sheet serving as a negative electrode by using a diaphragm and the organic selenium/telluride electrolyte in the step (1) to obtain the lithium-sulfur battery.
10. A lithium-sulfur battery, comprising a positive electrode, a negative electrode, an electrolyte, and a separator; the positive electrode is a polyacrylonitrile sulfide electrode, the negative electrode is a lithium sheet, the electrolyte is a blank ether electrolyte or a blank ester electrolyte, and soluble organic selenide and/or soluble organic telluride are added in the electrolyte; the diaphragm is a polypropylene diaphragm.
CN202110827262.5A 2021-07-21 2021-07-21 Method for generating high-activity S-Se/Te bonds to improve performance of lithium-sulfur battery Pending CN115692822A (en)

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