Preparation Method of Gel Polymer Electrolyte and Solid-State Battery

Abstract

The present invention belongs to the field of solid-state lithium batteries, and specifically discloses the preparation of a gel polymer electrolyte and its application in solid-state lithium-ion batteries. The gel electrolyte of the present invention comprises ethylene carbonate ethyl ester, azobisisobutyronitrile, polyethylene oxide, lithium bis(trifluoromethylsulfonyl)imide, CMOF and MIL-53(Al). CMOF and MIL-53(Al) are combined with PEO through hydrogen bonding to form a gel polymer electrolyte with a stable structure, high lithium-ion conductivity and good interfacial contact. The solid-state battery prepared from this gel polymer electrolyte has good cycle performance and safety.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid-state batteries, and in particular to a preparation method of a gel polymer electrolyte and a solid-state battery. Background Art

[0002] On the one hand, traditional liquid batteries will gradually form lithium dendrites during the continuous charging and discharging process, which can penetrate the diaphragm and cause the battery to short-circuit or cause the internal resistance of the battery to increase rapidly, eventually leading to the end of the life of the liquid lithium battery; on the other hand, due to the flammability of organic liquid electrolytes, traditional liquid batteries have fatal safety problems. Solid-state batteries are considered to be one of the future technologies of lithium batteries because they can avoid electrolyte leakage or safety accidents. The research and development of solid-state electrolytes is a very important direction. The current mainstream electrolytes are generally divided into: composite polymer electrolytes, inorganic solid electrolytes, and gel electrolytes (quasi-solid-state electrolytes). Among them, gel electrolytes have better plasticity and lower interface resistance than solid electrolytes; at the same time, they can also inhibit the formation of lithium dendrites, and are safer and more stable. However, some organic non-conductive fillers in gel electrolytes may not be able to balance ion conduction and interface compatibility at the same time. Summary of the invention

[0003] The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art and provide a method for preparing a gel polymer electrolyte.

[0004] A technical solution adopted by the present invention to solve the technical problem is: a method for preparing a gel polymer electrolyte, comprising the following steps:

[0005] S1. Put polyethylene oxide, lithium bis(trifluoromethylsulfonyl)imide, CMOF, MIL-53 (Al), azobis(isobutyronitrile) into a vacuum oven and dry at below 80°C for 24 hours to remove moisture;

[0006] S2. Stir at 80°C to 100°C for 2h to completely dissolve the polyethylene oxide for later use;

[0007] S3. Dissolve lithium bis(trifluoromethylsulfonyl)imide in vinylene carbonate, and then add CMOF, MIL-53 (Al), and azobisisobutyronitrile solid particles in sequence, stir evenly, and finally add the polyethylene oxide solution in step S2, stir well to mix evenly to obtain a mixed solution, and the mixed solution is in situ polymerized at 70-80°C to obtain a CMOF / MIL-53 (Al) gel polymer electrolyte.

[0008] Furthermore, the CMOF is a conductive metal organic framework, and its chemical formula is D-UiO-66-NH2.

[0009] Further, the MIL-53(Al) is a metal-organic framework with the chemical formula C8H5AlO5.

[0010] Further, both the CMOF and MIL-53(Al) are nanomaterials with a porous structure.

[0011] The CMOF is connected to the ether oxygen of the polyethylene oxide molecular chain through an amino group by a hydrogen bond. The hydroxyl group on the surface of MIL-53(Al) combines with the hydroxyl group on the PEO molecular chain to form a structurally stable electrolyte; the two substances, CMOF and MIL-53(Al), strengthen the fixation of anions through electrostatic interaction and high specific surface area adsorption pathways respectively, creating a stable and efficient Li + (lithium ion) channel, further improving the lithium ion conductivity of the gel polymer electrolyte; the high specific surface area can also increase the contact points and reduce the interfacial resistance; moreover, both CMOF and MIL-53(Al) are nanomaterials with a porous structure, which helps to stabilize the interface between the solid electrolyte and the lithium metal.

[0012] A preparation method of a solid-state battery is also provided, including the following steps:

[0013] (1) Put the main components of the battery into a vacuum oven and dry them at a temperature below 80 °C for 24 h to remove moisture. Among them, the main components of the battery include a positive electrode case, a pole piece, a separator, a lithium sheet, a gasket and a negative electrode case;

[0014] (2) Drop 2 - 3 drops of the mixed solution described in step S3 above on the pole piece and the separator respectively;

[0015] (3) Assemble the positive electrode case, the pole piece, the separator, the lithium sheet, the gasket and the negative electrode case in sequence in a glove box, and let the assembled battery stand at room temperature for 2 h;

[0016] (4) In-situ polymerize the battery assembled in step (3) at 70 - 80 °C, and cool to obtain a solid-state battery.

[0017] In the above solution, the pole piece in step (3) is a LiFePO4 positive electrode material. This LiFePO4 positive electrode pole piece includes LiFePO4, a conductive agent Super-P, VGCF, and a binder PVDF, and their mass ratio is 8:0.5:0.5:1. The lithium sheet is a negative electrode material.

[0018] In the above solution, the pole piece under the positive electrode case in step (3) is a lithium sheet.

[0019] In the above solution, the in-situ polymerization in step (4) is carried out in a vacuum oven, and the polymerization time is 2 h - 9 h.

[0020] Another technical solution adopted by the present invention to solve the technical problem is: a method for preparing a gel polymer electrolyte, comprising the following steps:

[0021] Sa, put polyethylene oxide, lithium bis(trifluoromethylsulfonyl)imide, MIL-53 (Al), azobis(isobutyronitrile) into a vacuum oven and dry at below 80°C for 24 hours to remove moisture;

[0022] Sb, stirring at 80℃~100℃ for 2h to completely dissolve the polyethylene oxide for later use;

[0023] Sc. Dissolve lithium bis(trifluoromethylsulfonyl)imide in vinylene carbonate, then add MIL-53(Al) and azobisisobutyronitrile solid particles in sequence, stir evenly, and finally add the polyethylene oxide solution in step Sb, stir well to mix evenly to obtain a mixed solution, and the mixed solution is in situ polymerized at 70-80°C to obtain MIL-53(Al) gel polymer electrolyte.

[0024] CMOF can form a structurally stable electrolyte by connecting the amino group with the ether oxygen of the polyethylene oxide molecular chain through hydrogen bonds; CMOF strengthens the fixation of anions through electrostatic interaction and high specific surface area adsorption, creating a stable and efficient Li + (lithium ion) channels further improve the lithium ion conductivity of the gel polymer electrolyte; the high specific surface area can also increase the contact points and reduce the interface resistance; and CMOF is a porous nanomaterial that helps to stabilize the interface between the solid electrolyte and lithium metal.

[0025] A method for preparing a solid-state battery is also provided, comprising the following steps:

[0026] (a) placing the main components of the battery in a vacuum oven and drying them at a temperature below 80° C. for 24 hours to remove moisture, wherein the main components of the battery include a positive electrode shell, a pole piece, a separator, a lithium sheet, a gasket and a negative electrode shell;

[0027] (b) dropping 2 to 3 drops of the mixed solution described in step Sc above on the electrode and the diaphragm respectively;

[0028] (c) assembling the positive electrode shell, the electrode sheet, the separator, the lithium sheet, the gasket and the negative electrode shell in sequence in a glove box, and standing the assembled battery at room temperature for 2 hours;

[0029] (d) The battery assembled in step (3) is in-situ polymerized at 70-80° C. and cooled to obtain a solid-state battery.

[0030] The beneficial effects of the present invention are as follows: The CMOF and MIL-53(Al) of the present invention are combined with polyethylene oxide through hydrogen bonding to form a gel polymer electrolyte with stable structure, high lithium ion conductivity and good interfacial contact; and the solid-state battery prepared from the gel polymer electrolyte prepared by the present invention has good cycle performance and safety. Detailed Embodiments

[0031] Now, the present invention will be further described in conjunction with preferred embodiments. Only the basic structure of the present invention is illustrated in a schematic manner, so it only shows the components related to the present invention.

[0032] Example 1

[0033] First, polyethylene oxide (PEO), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), MIL-53(Al), azobisisobutyronitrile (AIBN) and the components of the battery are dried at 80 °C for 24 hours to remove moisture. Secondly, under the condition of 80 °C to 100 °C, stir for 2 hours to completely dissolve PEO and set aside; then dissolve LiTFSI in vinylene carbonate (VC) and mix evenly, and then add MIL-53(Al), AIBN and PEO solution in sequence and stir well to obtain a mixed solution; assemble the battery according to the order of button cell assembly: positive electrode shell, LiFePO4 positive electrode plate, mixed solution, separator, mixed solution, lithium sheet, gasket, negative electrode shell; finally, the assembled battery is in-situ polymerized and cooled at 70 °C to 80 °C to obtain a MIL-53(Al) gel polymer solid-state battery.

[0034] Among them, the mixed solution forms a MIL-53(Al) gel polymer electrolyte after in-situ polymerization at 70-80 °C.

[0035] Example 2

[0036] First, polyethylene oxide (PEO), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), CMOF, MIL-53(Al), azobisisobutyronitrile (AIBN) and the components of the battery are dried at 80 °C for 24 hours to remove moisture; secondly, under the condition of 80 °C to 100 °C, stir for 2 hours to completely dissolve PEO and set aside; then dissolve LiTFSI in vinylene carbonate (VC) and mix evenly, and then add CMOF, MIL-53(Al), AIBN and PEO solution in sequence and stir well to obtain a mixed solution; assemble the battery according to the order of button cell assembly: positive electrode shell, lithium sheet, electrolyte, separator, mixed solution, lithium sheet, gasket, negative electrode shell; finally, the assembled battery is in-situ polymerized and cooled at 70 °C to 80 °C to obtain a CMOF / MIL-53(Al) lithium metal symmetric battery.

[0037] Among them, the mixed solution forms a CMOF / MIL-53(Al) gel polymer electrolyte after in-situ polymerization under the condition of 70-80 °C.

[0038] Example 3

[0039] First, poly(ethylene oxide) (PEO), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), CMOF, MIL-53(Al), azobisisobutyronitrile (AIBN) and the components of the battery are dried at 80 °C for 24 hours to remove moisture; secondly, they are stirred at 80 °C - 100 °C for 2 hours to completely dissolve PEO for standby; then LiTFSI is dissolved in vinylene carbonate (VC) and mixed evenly, and then CMOF, MIL-53(Al), AIBN, and the PEO solution are added sequentially and stirred evenly to obtain a mixed solution; the battery is assembled in the order of button battery: positive electrode shell, LiFePO4 positive electrode plate, mixed solution, separator, mixed solution, lithium sheet, gasket, negative electrode shell; finally, the assembled battery is in-situ polymerized and cooled at 70 °C - 80 °C to obtain a CMOF / MIL-53(Al) gel polymer solid-state battery.

[0040] Among them, the mixed solution forms a CMOF / MIL-53(Al) gel polymer electrolyte after in-situ polymerization under the condition of 70-80 °C.

[0041] The batteries prepared in Examples 1-3 are cyclically charged to obtain the test data in the following table:

[0042]

[0043] The above data prove that the solid-state battery prepared from the CMOF / MIL-53(Al) gel polymer electrolyte has good cycling performance.

[0044] The above embodiments are only for illustrating the technical concept and characteristics of the present invention, and the purpose is to enable those familiar with this technology to understand the content of the present invention and implement it, and it cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for preparing a gel polymer electrolyte, characterized in that, The following steps are involved: S1. Put polyethylene oxide, lithium bis(trifluoromethylsulfonyl)imide, CMOF, MIL-53(Al), and azobis(isobutyronitrile) into a vacuum oven and dry them at below 80°C for 24 hours to remove moisture; the MIL-53(Al) is a metal organic framework with a chemical formula of C8H5AlO5; the CMOF is a conductive metal organic framework with a chemical formula of D-UiO-66-NH2; S2. Stir at 80°C to 100°C for 2h to completely dissolve the polyethylene oxide for later use; S3, dissolving lithium bis(trifluoromethylsulfonyl)imide in vinylene carbonate, and then sequentially adding CMOF, MIL-53(Al), and azobisisobutyronitrile solid particles, stirring evenly, and finally adding the polyethylene oxide solution in step S2, stirring well to mix evenly to obtain a mixed solution, and the mixed solution is in situ polymerized at 70-80°C to obtain a CMOF / MIL-53(Al) gel polymer electrolyte.

2. The preparation method of the gel polymer electrolyte according to claim 1, wherein: The CMOF and MIL-53 (Al) are both nanomaterials with porous structures.

3. A method for preparing a solid-state battery, characterized in that, The following steps are involved: (1) placing the main components of the battery in a vacuum oven and drying them at a temperature below 80° C. for 24 hours to remove moisture, wherein the main components of the battery include a positive electrode shell, a pole piece, a separator, a lithium sheet, a gasket and a negative electrode shell; (2) dropping 2 to 3 drops of the mixed solution as described in step S3 of claim 1 on the electrode and the diaphragm respectively; (3) Assembling the positive electrode shell, the electrode sheet, the separator, the lithium sheet, the gasket and the negative electrode shell in sequence in a glove box, and leaving the assembled battery to stand at room temperature for 2 hours; (4) The battery assembled in step (3) is in situ polymerized at 70-80° C. and cooled to obtain a solid-state battery.

4. The preparation method of a solid-state battery according to claim 3, characterized in that: The electrode sheet in step (3) is a LiFePO4 positive electrode material, which includes LiFePO4, a conductive agent Super-P, VGCF, and a binder PVDF, and their mass ratio is 8:0.5:0.5:

1. The lithium sheet is a negative electrode material.

5. The preparation method of a solid-state battery according to claim 3, characterized in that: The electrode sheet under the positive electrode shell in step (3) is a lithium sheet.

6. The preparation method of a solid-state battery according to claim 3, characterized in that: The in-situ polymerization in step (4) is carried out in a vacuum oven, and the polymerization time is 2h to 9h.

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