CN116111181A - Modified sulfide electrolyte and application thereof - Google Patents

Modified sulfide electrolyte and application thereof Download PDF

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Publication number
CN116111181A
CN116111181A CN202111329324.6A CN202111329324A CN116111181A CN 116111181 A CN116111181 A CN 116111181A CN 202111329324 A CN202111329324 A CN 202111329324A CN 116111181 A CN116111181 A CN 116111181A
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electrolyte
sulfide
modified
solid
monomer solution
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谢佳
余创
孙孟君
曾子琪
彭林峰
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Huazhong University of Science and Technology
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Huazhong University of Science and Technology
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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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/54—Electrolytes
    • H01G11/56—Solid electrolytes, e.g. gels; Additives therein
    • 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
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0065—Solid electrolytes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0088—Composites
    • 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
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The invention belongs to the technical field of sulfide electrolyte, and particularly discloses modified sulfide electrolyte and application thereof. The modified sulfide electrolyte is prepared by only using the sulfide electrolyte, the liquid monomer capable of undergoing polymerization reaction and the electrolyte salt, the sulfide electrolyte can trigger the liquid monomer to undergo polymerization, an additional initiator is avoided, the modified sulfide electrolyte can be used for improving the stability of the sulfide electrolyte and alkali metal, and the modified sulfide electrolyte can be used for preparing a sulfide electrolyte film.

Description

Modified sulfide electrolyte and application thereof
Technical Field
The invention belongs to the technical field of sulfide electrolytes, and particularly relates to a modified sulfide electrolyte and application thereof.
Background
The energy storage technology is applied to the distributed power grid, so that the energy utilization rate can be improved, the environmental pollution can be reduced, and the thermal economy and the safety and stability of the system can be improved. As an important energy storage mode, lithium ion batteries are widely used in production and life, but lithium ion batteries adopting organic liquid electrolytes have potential safety problems such as inflammable electrolyte, leakage of electrolyte and the like. The safety performance and the energy density of the battery can be effectively improved by adopting the solid electrolyte, and the solid electrolyte can be divided into sulfide electrolyte, oxide electrolyte and polymer electrolyte. Among them, sulfide electrolyte has high ionic conductivity and has a certain plasticity, which is advantageous in increasing the contact area of electrodes/electrolyte, and thus sulfide electrolyte is considered as one of the most promising solid electrolytes.
However, the existing sulfide electrolyte still has the defects of brittleness, poor flexibility and easy cracking under stress, and is difficult to apply to the soft-package battery with high capacity, and the advantage of high energy density of the battery is difficult to embody. And polymer electrolyte with good flexibility and film forming property is introduced into sulfide electrolyte, so that the defect can be well compensated. However, it is often necessary to add an initiator to initiate polymerization of the monomer and to obtain a polymer electrolyte, and the added initiator tends to undergo side reactions with other components in the battery, thereby adversely affecting the battery performance.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a modified sulfide electrolyte and application thereof, wherein the modified sulfide electrolyte can be prepared by only using sulfide solid electrolyte, monomers capable of undergoing polymerization reaction and electrolyte salt, and no initiator is required to be additionally added, so that the obtained modified sulfide electrolyte has the dual advantages of sulfide electrolyte and polymer electrolyte.
In order to achieve the above object, the present invention provides a modified sulfide electrolyte formed by polymerizing a monomer solution including a liquid monomer that can be polymerized by initiation of a sulfide solid electrolyte and an electrolyte salt dissolved in the monomer, as an initiator.
Preferably, the liquid monomer is one or more of cyclic lactone, acrylic ester oligomer with single side still containing double bonds and cyanoacrylate.
Preferably, the sulfide solid state electrolyte is in a glassy state, a glass ceramic state, or a crystalline state.
Preferably, the sulfide solid state electrolyte is one or more of a thio-LISICON type, an LGPS type, a sulfur silver germanium ore type, and a NASICON type.
Preferably, the electrolyte salt concentration in the monomer solution is less than or equal to 3mol/L.
Preferably, the preparation method of the modified sulfide electrolyte comprises the following steps: pressing the sulfide solid electrolyte into a sheet shape, then dripping a monomer solution on the surface of the sheet sulfide solid electrolyte, standing for a period of time at room temperature, and polymerizing the monomer solution on the surface of the sheet sulfide solid electrolyte to form a polymer electrolyte film to obtain a modified sulfide electrolyte;
the modified sulfide electrolyte is used in an all-solid-state energy storage device with alkali metal as a negative electrode, and the polymer electrolyte film can prevent side reaction between the sulfide solid-state electrolyte and the alkali metal negative electrode, so that the stability of the sulfide solid-state electrolyte and the alkali metal negative electrode is improved.
Preferably, the preparation method of the modified sulfide electrolyte comprises the following steps: mixing a monomer solution and a sulfide solid electrolyte according to a certain proportion and grinding to obtain slurry; placing the obtained slurry on a substrate, standing at room temperature for a period of time, and initiating the polymerization of liquid monomers by using sulfide solid electrolyte to generate polymer electrolyte, and forming an electrolyte membrane on the substrate; and (3) pressurizing and thinning the obtained electrolyte membrane, and then stripping the electrolyte membrane from the substrate to obtain the modified sulfide electrolyte membrane.
Further preferably, the obtained slurry is knife coated or spin coated on a substrate, left at room temperature for a period of time, and rolled and thinned after an electrolyte membrane is formed on the substrate.
Further preferably, the mass ratio of the sulfide solid electrolyte to the monomer solution is 1 (0.04 to 24).
According to another aspect of the present invention, there is also provided an all-solid-state energy storage device comprising the modified sulfide electrolyte described above.
In general, the above technical solutions conceived by the present invention have the following beneficial effects compared with the prior art:
(1) The modified sulfide electrolyte provided by the invention utilizes the characteristics of the sulfide electrolyte to initiate the polymerization of the monomer to generate the polymer electrolyte, avoids using an initiator which is unfavorable for the performance of the energy storage device, combines the sulfide solid electrolyte with the polymer electrolyte, has higher ionic conductivity and better flexibility, and is suitable for preparing an electrolyte film.
(2) According to the invention, the monomer solution is dripped on the surface of the sulfide electrolyte sheet, the sulfide electrolyte can initiate polymerization of the monomer solution and form a thin polymer electrolyte layer on the surface of the sulfide electrolyte sheet, and the prepared modified sulfide electrolyte is used as the electrolyte in the solid alkali metal battery, so that the sulfide electrolyte and the alkali metal negative electrode can be separated, and further, the side reaction of the sulfide electrolyte and the alkali metal is inhibited. Compared with the traditional element doping method for improving the stability of sulfide solid electrolyte and alkali metal, the method is simple and efficient, has low cost, and avoids the complicated steps of high-speed ball milling and high-temperature sintering and the energy consumption thereof.
(3) According to the invention, the sulfide solid electrolyte and the monomer solution are mixed and ground, and the monomer solution is polymerized by in-situ initiation of sulfide electrolyte particles, so that the generated polymer electrolyte is tightly combined with the sulfide electrolyte, the polymer electrolyte plays a role of a binder, the mechanical strength of a sulfide electrolyte sheet can be obviously improved, and the thickness of a sulfide electrolyte membrane is reduced. Compared with the traditional sulfide electrolyte membrane preparation method, the method effectively avoids the use of binders and solvents, simplifies the preparation process of the sulfide electrolyte membrane, and is suitable for preparing sulfide electrolyte membranes with different shapes.
(4) The modified sulfide electrolyte provided by the invention is used in an all-solid-state energy storage device, has high ionic conductivity and good flexibility, enables interface contact between the electrolyte and an electrode of the all-solid-state energy storage device to be good, has excellent electrochemical stability, and is particularly suitable for being used as the electrolyte of a high-energy-density soft-package battery.
Drawings
FIG. 1 is Li in example 1 of the present invention 5.5 PS 4.5 Cl 1.5 Electrolyte sheet and PCL-Li prepared 5.5 PS 4.5 Cl 1.5 XRD pattern of the electrolyte sheet.
FIG. 2 is Li in example 1 of the present invention 5.5 PS 4.5 Cl 1.5 A surface topography (a) and a cross-sectional topography (b) of the electrolyte sheet.
FIG. 3 shows PCL-Li prepared in example 1 of the present invention 5.5 PS 4.5 Cl 1.5 A surface topography (a) and a cross-sectional topography (b) of the electrolyte sheet.
FIG. 4 is Li in example 1 of the present invention 5.5 PS 4.5 Cl 1.5 Electrolyte sheet and PCL-Li prepared 5.5 PS 4.5 Cl 1.5 Lithium ion conductivity map of the electrolyte sheet.
FIG. 5 shows PCL-Li prepared in example 1 of the present invention 5.5 PS 4.5 Cl 1.5 Electrolyte sheet (a) and Li 5.5 PS 4.5 Cl 1.5 Impedance diagram corresponding to lithium ion conductivity diagram of electrolyte sheet (b).
FIG. 6 is a nuclear magnetic resonance H-spectrum of a polymer electrolyte membrane and monomers used for a polymer in example 1 of the present invention.
Fig. 7 is a graph showing the cycle performance of the Li/Li battery prepared in comparative example 1 of the present invention at various current densities.
FIG. 8 is a graph of the comparative example 1 of the present inventionLi/Li cell at 0.1mA cm -2 Cycling performance plot at current density.
Fig. 9 is a graph showing the cycle performance of the Li/Li battery prepared in example 7 of the present invention at various current densities.
FIG. 10 is a graph showing that the Li/Li battery prepared in example 7 of the present invention was measured at 0.1mAcm -2 Cycling performance plot at current density.
Fig. 11 is an XRD pattern of the modified sulfide electrolyte membrane prepared in examples 9 to 12 of the present invention.
Fig. 12 is a lithium ion conductivity diagram of the modified sulfide electrolyte membranes prepared in examples 9 to 12 of the present invention.
Fig. 13 is a surface topography of a modified sulfide electrolyte membrane prepared in example 12 of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
A modified sulfide electrolyte formed by polymerizing a sulfide solid state electrolyte as an initiator to initiate a monomer solution comprising a liquid monomer that can be initiated by the sulfide solid state electrolyte to undergo polymerization and an electrolyte salt dissolved in the monomer.
The modified sulfide electrolyte provided by the invention comprises the sulfide solid electrolyte and the polymer electrolyte, wherein the polymer electrolyte is formed by polymerizing a monomer solution initiated by the sulfide solid electrolyte, an initiator is not required to be additionally added, side reactions of an external initiator and other components in a battery are effectively avoided, and the obtained modified sulfide electrolyte has the dual advantages of the sulfide solid electrolyte and the polymer electrolyte, and has good ion conduction capability, and better flexibility and plasticity.
The liquid monomers of the present invention include, but are not limited to, cyclic lactones, acrylates and acrylate oligomers thereof having a double bond on one side, cyanoacrylatesOne or more of the esters, preferably one or more of lactide, caprolactone or polyethylene glycol dimethacrylate. The sulfide solid state electrolyte includes, but is not limited to, a glassy state, a glass ceramic state, or a crystalline state, wherein the crystalline state sulfide solid state electrolyte includes, but is not limited to, one or more of a thio-LISICON type, an LGPS type, a silver germanium sulfide ore (Argyrodite) type, and a NASICON type. Further preferably, the sulfide solid state electrolyte is Li 5.5 PS 4.5 Cl 1.5 、Na 3.75 [Sn 0.67 Si 0.33 ] 0.75 P 0.25 S 4 Or Na (or) 3.57 [Sn 0.67 Si 0.33 ] 0.67 P 0.33 S 3.9 X 0.1 Wherein X is Cl, br or I. The electrolyte salt is lithium salt, sodium salt or potassium salt.
Preferably, the lithium salt is lithium hexafluorophosphate (LiPF 6 ) Lithium hexafluoroarsenate (LiAsF) 6 ) Lithium perchlorate (LiClO) 4 ) Lithium tetrafluoroborate (LiBF) 4 ) Lithium bis (trifluoromethylsulfonyl) imide (LiTFSI), lithium bis (fluorosulfonyl) imide (LiWSI), lithium bis (oxalato) borate (LiBOB), lithium difluoro (LiDFOB) oxalato borate (LiDFOB), and lithium trifluoromethane sulfonate (LiCF) 3 SO 3 )。
The sodium salt is sodium hexafluorophosphate (NaPF) 6 ) Sodium perchlorate (NaClO) 4 ) Sodium tetrafluoroborate (NaBF) 4 ) Sodium bis (trifluoromethylsulfonyl) imide (NaTFSI), sodium bis (fluorosulfonyl) imide (NaFSI), sodium bis (BOB) oxalate borate (NaBOB), sodium difluoro (NaDFOB) oxalate borate and sodium trifluoro-methanesulfonate (NaCF) 3 SO 3 )。
The potassium salt is potassium hexafluorophosphate (KPF) 6 ) Potassium hexafluoroarsenate (KAsF) 6 ) Potassium perchlorate (KClO) 4 ) Potassium tetrafluoroborate (KBF) 4 ) Potassium bis (trifluoromethylsulfonyl) imide (KTFSI), potassium bis (fluorosulfonyl) imide (KFSI) and potassium trifluoromethylsulfonate (KCF) 3 SO 3 )。
In some embodiments, the electrolyte salt concentration in the monomer solution is less than or equal to 3mol/L.
In general, a solid-state energy storage device with high energy density needs to use alkali metal as a negative electrode, but side reactions are easy to occur between sulfide electrolyte and alkali metal, so that instability of sulfide electrolyte and alkali metal negative electrode is caused, thereby affecting the performance of the energy storage device, and seriously impeding the application of sulfide electrolyte in an all-solid-state energy storage device. The methods commonly used at present for improving the stability of sulfide electrolyte and alkali metal are as follows: alloy type negative electrodes and element doping are prepared, but the methods involve complex processes and high cost.
In order to overcome the defects in the prior art, the invention provides a preparation method of a modified sulfide electrolyte, which comprises the following steps: pressing the sulfide solid electrolyte into a sheet shape, then dripping a monomer solution on the surface of the sheet sulfide solid electrolyte, standing for a period of time at room temperature, and polymerizing the monomer solution on the surface of the sheet sulfide solid electrolyte to form a polymer electrolyte film to obtain the modified sulfide electrolyte.
The modified sulfide electrolyte is used in an all-solid-state energy storage device with alkali metal as a negative electrode, and because the polymer electrolyte film is formed on the surface of the sulfide electrolyte sheet, the sulfide electrolyte and the alkali metal can be effectively separated, and side reactions between the sulfide electrolyte and the alkali metal are inhibited, so that the stability of the sulfide electrolyte and the alkali metal is improved.
In some embodiments, the rest time at room temperature is 1h to 3h.
At present, a solid electrolyte sheet used in a sulfide-based all-solid-state battery is usually prepared by a battery mold cold pressing or hot pressing technology, but the sulfide electrolyte sheet prepared by the method has small area, thicker area, brittleness and poor flexibility, is difficult to apply to a high-capacity soft-package battery, and the advantage of high energy density of the battery is difficult to embody. Therefore, it is very important and urgent to prepare a sulfide solid electrolyte membrane having good ion-conducting ability and mechanical properties.
The invention provides a preparation method of a modified sulfide electrolyte membrane, which comprises the following steps:
s1, mixing a monomer solution and a sulfide solid electrolyte according to a certain proportion and grinding to obtain slurry;
s2, placing the slurry obtained in the step S1 on a substrate, standing at room temperature for a period of time, and initiating the polymerization of a liquid monomer by using a sulfide solid electrolyte to generate a polymer electrolyte, and forming an electrolyte membrane on the substrate;
and S3, pressurizing and thinning the electrolyte membrane obtained in the step S2, and then stripping the electrolyte membrane from the substrate to obtain the modified sulfide electrolyte membrane.
The sulfide solid electrolyte and the polymer electrolyte in the modified sulfide electrolyte membrane prepared by the invention are tightly compounded together, and form a continuous ion transmission channel together; the sulfide solid electrolyte is used as a main body of the ion transmission channel, and the polymer electrolyte plays a role of a binder, so that the mechanical strength of the modified sulfide electrolyte membrane can be remarkably improved. Compared with the existing sulfide electrolyte membrane preparation method, the method utilizes the characteristic that the sulfide electrolyte can initiate the polymerization of the liquid monomer, effectively avoids the use of binder and solvent, simplifies the preparation process of the sulfide electrolyte membrane, can prepare sulfide electrolyte membranes with different shapes, and has wide application prospect in all-solid-state energy storage devices.
Specifically, in the steps S2 and S3, the obtained slurry is coated on a substrate in a scraping way or spin way, and stands for 1 to 3 hours at room temperature to form an electrolyte membrane on the substrate; and rolling and thinning the obtained electrolyte membrane to obtain the modified sulfide electrolyte membrane. Wherein for knife coating, the thickness of the film is controlled by varying the thickness of the knife.
For the spin coating, in order to achieve a better spin coating effect, the slurry is diluted by a nonpolar solvent or a low-polar solvent, wherein the nonpolar solvent or the low-polar solvent comprises but is not limited to ethyl acetate, fluorobenzene, trifluorobenzene, chlorobenzene, o-dichlorobenzene, xylene, phenol, dichloromethane, chloroform, 1, 2-dichloroethane and chloroform, the concentration of the diluted slurry is about 0.05g/L to 0.2g/L, the diluted slurry is dripped on a substrate, the spin coating speed is adjusted to 500rpm/s and the spin coating time is adjusted to 30s, the concentration and the volume of the slurry are unchanged, and the number of spin coating times is changed to control the thickness of the film.
The rolling temperature is 25-100 ℃ for the rolling thinning process.
Or directly placing the obtained slurry between two layers of substrates, standing for 1-3 h at room temperature, and forming an electrolyte membrane between the two layers of substrates; and then hot-pressing or cold-pressing by using a hot press for a certain time to obtain the sulfide electrolyte membrane. When hot pressing is adopted, the hot pressing temperature is 40-100 ℃, and the hot pressing time is 0.5-24 h; when cold pressing is adopted, the cold pressing temperature is room temperature environment, and the cold pressing time is 0.5-24 h.
In some embodiments, the substrate used in the present invention is preferably a Polytetrafluoroethylene (PTFE) film.
In some embodiments, the mass ratio of sulfide solid state electrolyte to monomer solution is 1 (0.04-24), preferably 1 (0.04-0.9), and more preferably 4:1.
In some embodiments, the modified sulfide electrolyte membrane has a thickness of 5 μm to 500 μm.
The all-solid-state energy storage device provided by the invention can be an all-solid-state chemical battery or an all-solid-state supercapacitor, and comprises the modified sulfide electrolyte provided by the invention.
The modified sulfide electrolyte provided by the invention is used as the electrolyte of the all-solid-state energy storage device, and has the advantages of sulfide electrolyte and polymer electrolyte, so that the interface contact between the electrolyte and the electrode of the all-solid-state energy storage device is good, and the all-solid-state energy storage device has better multiplying power performance and circulation stability.
The invention provides a preparation method of a solid alkali metal battery, which comprises the following steps: firstly, the sulfide solid electrolyte is packed in a die battery and pressed into a sheet, then the anode is paved on one side, the monomer solution is dripped on the other side after compaction, after standing for a period of time at room temperature, the monomer solution is polymerized to form a polymer film, and then the alkali metal cathode is assembled on the side, so that the solid battery is obtained.
The invention provides a preparation method of a solid alkali metal battery, which comprises the following steps: the modified sulfide electrolyte membrane prepared by the method is assembled between a positive electrode and an alkali metal negative electrode to obtain the solid-state battery.
In some embodiments, the alkali metal negative electrode is lithium metal, sodium metal, or potassium metal.
In some embodiments, the active material of the positive electrode is lithium iron phosphate, lithium cobalt oxide, ternary nickel cobalt manganese, sulfur positive electrode, sulfurized polyacrylonitrile, sodium iron phosphate, sodium alum phosphate, or potassium manganese iron cyanide (e.g., K 2 Mn[Fe(CN) 6 ])。
The following describes the above technical scheme in detail with reference to specific embodiments.
Example 1
Solid electrolyte Li of sulfide 5.5 PS 4.5 Cl 1.5 Pressing into electrolyte sheet with thickness of about 80 μm; liTFSI was dissolved in caprolactone to give a solution containing 1mol L -1 Caprolactone solution of LiTFSI; and then dripping the caprolactone solution on the surface of the electrolyte sheet, and standing for 2 hours to obtain the modified sulfide electrolyte sheet.
Sulfide solid electrolyte and modified sulfide electrolyte (denoted as PCL-Li 5.5 PS 4.5 Cl 1.5 ) XRD measurements were performed, as shown in FIG. 1, and caprolactone had no effect on the sulfide structure after polymerization on the sulfide electrolyte sheet surface.
SEM characterization of both electrolytes, as shown in fig. 2 and 3, the caprolactone can form a polymer film layer of about 10 μm on the surface of the sulfide electrolyte and the polymer layer is mainly formed on the surface of the sulfide electrolyte sheet.
The two electrolytes were subjected to conductivity testing, as shown in FIGS. 4 and 5, li 5.5 PS 4.5 Cl 1.5 Is 5.6X10 of lithium ion conductivity -3 S cm -1 ，PCL-Li 5.5 PS 4.5 Cl 1.5 Is 10 in lithium ion conductivity at room temperature -4 Scm -1 。
Dissolving the obtained modified sulfide electrolyte sheet in deuterated chloroform, filtering the obtained solution with polytetrafluoroethylene filter membrane to obtain clear solution, subjecting the solution to nuclear magnetic resonance H spectrum test, and simultaneously subjecting caprolactone monomer to nuclear magnetic resonance H spectrum test (deuterated chloroform as solvent), as shown in figure 6Polymerization to form polycaprolactone, indicating Li 5.5 PS 4.5 Cl 1.5 Can initiate the polymerization of caprolactone.
Example 2
As in example 1, except that the monomer solution was 3mol L -1 Caprolactone solution of LiFSI.
Example 3
The difference from example 1 is that the solvent in the monomer solution is a mixed solution of caprolactone monomer and lactide monomer, and the mass ratio of caprolactone to lactide is 9:1.
Example 3
The difference to example 4 is that the mass ratio of caprolactone to lactide is 8:2.
Example 5
As in example 1, except that the monomer solution was a solution containing 1mol L -1 Polyethylene glycol dimethacrylate solution of LiTFSI.
Example 6
As in example 1, but Na was used for sulfide electrolyte 3.75 [Sn 0.67 Si 0.33 ] 0.75 P 0.25 S 4 The monomer solution contains 1mol L -1 Caprolactone solution of naffsi.
Comparative example 1
Li used in the same example 1 5.5 PS 4.5 Cl 1.5 Lithium sheets were stacked on both sides of the electrolyte sheet, respectively, and symmetrical batteries were assembled, and cyclic performance was tested at different current densities, as shown in fig. 7, li 5.5 PS 4.5 Cl 1.5 Critical current density for metallic lithium is 0.3mA cm -2 。
For an assembled Li/Li cell at 0.1mA cm -2 The cycle performance was tested at a current density of 0.1mA cm as shown in FIG. 8 -2 At the same time, the polarization potential during the cycle was continuously increased, indicating Li 5.5 PS 4.5 Cl 1.5 Poor stability with lithium metal and continuous side reaction.
Example 7
Prepared in example 1PCL-Li 5.5 PS 4.5 Cl 1.5 Lithium sheets were stacked on both sides of the electrolyte sheet, respectively, and symmetrical batteries were assembled, and cyclic performance was tested at different current densities, as shown in fig. 9, PCL-Li 5.5 PS 4.5 Cl 1.5 Critical current density for metallic lithium is 2mA cm -2 。
For an assembled Li/Li cell at 0.1mA cm -2 The cycle performance was tested at a current density of 0.1mA cm as shown in FIG. 10 -2 The polarization potential during circulation was almost unchanged, indicating PCL-Li 5.5 PS 4.5 Cl 1.5 Has better stability with lithium metal, and the modified sulfide electrolyte can obviously improve Li by comparing with comparative example 1 5.5 PS 4.5 Cl 1.5 Stability with lithium metal.
Example 8
As in example 7, except that in PCL-Li 5.5 PS 4.5 Cl 1.5 And adding a metal lithium cathode on one side of the electrolyte sheet, adding a positive active material lithium iron phosphate on the other side of the electrolyte sheet, and assembling the battery for testing.
Example 9
LiTFSI was dissolved in caprolactone to give a solution containing 1mol L -1 LiTFSI caprolactone solution. Solid electrolyte Li of sulfide 5.5 PS 4.5 Cl 1.5 Mixing the solution with the caprolactone solution according to the mass ratio of 50:50, and grinding to obtain electrolyte membrane slurry; adding ethyl acetate into the obtained electrolyte membrane slurry, uniformly mixing, adjusting the concentration of the diluted slurry to 0.1g/L, spin-coating the diluted slurry on a PTFE substrate at the spin-coating speed of 500rpm/s for 30s, standing at room temperature for 2h, and carrying out Li 5.5 PS 4.5 Cl 1.5 Initiating liquid caprolactone polymerization, and forming a modified sulfide solid electrolyte membrane on the substrate; and then rolling and thinning the obtained electrolyte membrane, wherein the rolling temperature is 60 ℃, and finally stripping the electrolyte membrane from the PTFE membrane substrate to obtain the thin modified sulfide electrolyte membrane.
Example 10
As in example 9, except,sulfide solid electrolyte Li 5.5 PS 4.5 Cl 1.5 The mass ratio of the polymer to the monomer solution is 60:40.
Example 11
As in example 9, except that sulfide solid electrolyte Li 5.5 PS 4.5 Cl 1.5 The mass ratio of the polymer to the monomer solution was 70:30.
Example 12
As in example 9, except that sulfide solid electrolyte Li 5.5 PS 4.5 Cl 1.5 The mass ratio of the polymer to the monomer solution was 80:20.
XRD tests were performed on the modified sulfide electrolyte membranes obtained in examples 9 to 12, and as shown in fig. 11, the composite electrolyte membrane showed XRD with peaks of both polymer electrolyte and sulfide electrolyte, indicating successful preparation of the composite electrolyte membrane and no influence of the resulting polymer on the sulfide electrolyte. The modified sulfide electrolyte membranes obtained in examples 9 to 12 were subjected to lithium ion conductivity test, and as shown in FIG. 12, it was found that the ion conductivities of the composite electrolyte membranes obtained in examples 10 to 12 were all up to about 10 -4 S cm -1 The composite electrolyte membrane of example 9 has lower ionic conductivity at lower temperature, but the ionic conductivity can reach 10 after the temperature is increased -4 S cm -1 This may be because the monomer concentration in the slurry is high, the monomer is not completely polymerized, and as the temperature increases, the monomer that is not polymerized is further polymerized. Characterization of the morphology of the electrolyte membrane obtained in example 12, it can be seen from fig. 13 that sulfide electrolyte particles are connected by a polymer electrolyte to constitute an organic-inorganic composite electrolyte membrane.
From the above examples, the modified sulfide electrolyte prepared by the invention avoids the use of an initiator which is unfavorable for the battery performance, and the preparation method is simple, rapid and low in cost, and has a very wide application prospect. According to the method, the polymer electrolyte film is formed on the surface of the sulfide electrolyte sheet in situ by adopting the liquid monomer, so that the stability of different types of sulfide electrolytes and alkali metals can be improved; in addition, the compatibility of the solid-solid interface in the all-solid battery can be effectively improved due to the fluidity of the liquid. In the modified sulfide electrolyte membrane prepared by the invention, a continuous alkali metal ion transmission channel is formed by the sulfide solid electrolyte and the polymer electrolyte; the sulfide solid electrolyte is used as a main body of the ion transmission channel, and the polymer electrolyte plays a role of a binder, so that the mechanical strength of the modified sulfide electrolyte membrane can be remarkably improved, and the thickness of the sulfide electrolyte membrane is reduced.
It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.

Claims (10)

1. A modified sulfide electrolyte characterized by: the monomer solution is formed by initiating polymerization of a monomer solution by using a sulfide solid electrolyte as an initiator, wherein the monomer solution comprises a liquid monomer which can be initiated by the sulfide solid electrolyte to perform polymerization reaction and electrolyte salt dissolved in the monomer.
2. The modified sulfide electrolyte of claim 1, wherein: the liquid monomer is one or more of cyclic lactone, acrylic ester oligomer with double bond on one side and cyanoacrylate.
3. The modified sulfide electrolyte of claim 1, wherein: the sulfide solid state electrolyte is in a glassy state, a glass ceramic state or a crystalline state.
4. A modified sulfide electrolyte as claimed in claim 3, characterized in that: the sulfide solid electrolyte is one or more of thio-LISICON type, LGPS type, sulfur silver germanium ore type and NASICON type.
5. The modified sulfide electrolyte of claim 1, wherein: the electrolyte salt concentration in the monomer solution is less than or equal to 3mol/L.
6. The modified sulfide electrolyte as claimed in any one of claims 1 to 5, wherein the preparation method of the modified sulfide electrolyte comprises the steps of: pressing the sulfide solid electrolyte into a sheet shape, then dripping a monomer solution on the surface of the sheet sulfide solid electrolyte, standing for a period of time at room temperature, and polymerizing the monomer solution on the surface of the sheet sulfide solid electrolyte to form a polymer electrolyte film to obtain a modified sulfide electrolyte;
the modified sulfide electrolyte is used in an all-solid-state energy storage device with alkali metal as a negative electrode, and the polymer electrolyte film can prevent side reaction between the sulfide solid-state electrolyte and the alkali metal negative electrode, so that the stability of the sulfide solid-state electrolyte and the alkali metal negative electrode is improved.
7. The modified sulfide electrolyte as claimed in any one of claims 1 to 5, wherein the preparation method of the modified sulfide electrolyte comprises the steps of: mixing a monomer solution and a sulfide solid electrolyte according to a certain proportion and grinding to obtain slurry; placing the obtained slurry on a substrate, standing at room temperature for a period of time, and initiating the polymerization of liquid monomers by using sulfide solid electrolyte to generate polymer electrolyte, and forming an electrolyte membrane on the substrate; and (3) pressurizing and thinning the obtained electrolyte membrane, and then stripping the electrolyte membrane from the substrate to obtain the modified sulfide electrolyte membrane.
8. The modified sulfide electrolyte as claimed in claim 7, wherein: and (3) carrying out blade coating or spin coating on the obtained slurry on a substrate, standing for a period of time at room temperature, forming an electrolyte membrane on the substrate, and carrying out rolling thinning.
9. The modified sulfide electrolyte as claimed in claim 7, wherein: the mass ratio of the sulfide solid electrolyte to the monomer solution is 1 (0.04-24).
10. An all-solid-state energy storage device, characterized in that: comprising the modified sulfide electrolyte as claimed in any one of claims 1 to 9.
CN202111329324.6A 2021-11-10 2021-11-10 Modified sulfide electrolyte and application thereof Pending CN116111181A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117638268A (en) * 2024-01-25 2024-03-01 四川新能源汽车创新中心有限公司 Application of ester substance as surface modifier, battery pole piece and preparation method

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117638268A (en) * 2024-01-25 2024-03-01 四川新能源汽车创新中心有限公司 Application of ester substance as surface modifier, battery pole piece and preparation method
CN117638268B (en) * 2024-01-25 2024-04-23 四川新能源汽车创新中心有限公司 Application of ester substance as surface modifier, battery pole piece and preparation method

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