A sodium-ion battery electrode with a photocurable electrolyte coating and a sodium-ion battery

Abstract

The present invention discloses a sodium-ion battery electrode sheet with a photocurable electrolyte coating and a sodium-ion battery. An electrolyte film layer formed by ultraviolet curing of an electrolyte composition is provided on the negative electrode, which is made of mercapto-terminated polyethylene glycol, olefin-terminated polysiloxane, crosslinking agent, photoinitiator, sodium salt, inorganic solid electrolyte, etc. The present invention is particularly suitable for preparing sodium-ion bipolar batteries and is prepared by laminating bipolar substrates. The photocurable electrolyte film layer can be completely cured within 30 s at room temperature, and a separator with a thickness of 10-30 μm and excellent film-forming property and mechanical strength can be further obtained.

Description

Technical Field

[0001] The present invention relates to the field of solid electrolyte membranes, and more specifically to a sodium-ion battery electrode sheet with a photocurable electrolyte coating and a sodium-ion battery. Background Art

[0002] Numerous studies have shown that liquid electrolytes participate in most of the reactions during the thermal runaway process of the battery and significantly reduce the initial reaction temperature of the battery, that is, lower the threshold of thermal runaway. Therefore, improving the safety of the electrolyte is one of the most effective ways to achieve battery safety. The physical properties of liquid electrolytes determine that leakage is always inevitable, and it is also not conducive to reducing the battery volume to improve the energy density. Therefore, in order to improve the energy density and safety, the solidification of electrolytes has become a trend. Solid-state batteries not only have higher safety but also can be assembled in series and parallel first and then assembled, reducing the material used for the packaging shell and greatly simplifying the PACK design, which also improves the energy density after battery grouping.

[0003] Currently, the method for preparing solid electrolyte membranes is the in-situ thermal polymerization method. The thickness of the solid electrolyte membranes prepared by this method is uncontrollable, and the uniformity on the surface of the electrode sheet cannot be controlled either, and the polymerization film-forming reaction time is relatively long.

[0004] Sodium-ion batteries achieve different capacities by stacking multiple layers of positive and negative electrode sheets or winding the positive and negative electrodes. The tab width of the stacked and wound structures is much smaller than the electrode sheet width, and the current collection of the positive and negative electrode sheets is concentrated at the tabs. The excessive current causes the temperature to rise here, and even the tabs may melt. To ensure that there is enough tab cross-sectional area to meet the design of carrying current, thinner positive and negative current collectors cannot be used, resulting in ineffective improvement of the charge and discharge performance of sodium-ion batteries. Summary of the Invention

[0005] Object of the Invention: The object of the present invention is to provide a sodium-ion battery electrode sheet with fast photocuring performance, excellent film-forming property and ionic conductivity; another object of the present invention is to provide a solid sodium-ion battery prepared by using the aforementioned battery electrode sheet.

[0006] Technical Solution: To achieve the above object of the invention, a sodium-ion battery electrode sheet with a photocurable electrolyte coating of the present invention is provided, and an electrolyte film layer formed by ultraviolet curing of an electrolyte composition is provided on the negative electrode of the electrode sheet. The electrolyte composition includes: mercapto-terminated polyethylene glycol, olefin-terminated polysiloxane, crosslinking agent, photoinitiator, sodium salt, inorganic solid electrolyte and solvent.

[0007] The ultraviolet light-cured polymer formed by the thiol double-terminated polyethylene glycol, olefin double-terminated polysiloxane and crosslinking agent provided by the present invention is based on the thiol-ene Click chemistry reaction, which was first proposed by American chemist K.Barry Sharpless in 2001. A photoinitiator is used as a catalyst, and the free radicals are cracked under light or heating conditions to form free radicals. The free radicals capture the hydrogen atoms on the thiol group to generate thiol free radicals, which attack the carbon-carbon double bonds of the olefin group to transfer the active center and generate alkyl free radicals. The alkyl free radicals will capture the hydrogen atoms of other thiol groups, generate thiol free radicals again, and enter the cycle. At present, the reaction is mainly used in bioengineering and electronic component material engineering, and has not been used in the field of electrochemical materials.

[0008] Among them, the thiol double-terminated polyethylene glycol is preferably a linear HS-PEG-SH with an average molecular weight of 200-1000Da, and a more preferred molecular weight range is 400-800Da; the terminal alkenyl group of the olefin double-terminated polysiloxane is a C2-C4 straight chain or linear alkenyl group, preferably a vinyl double-terminated polysiloxane, such as the compound described in formula I, with an average molecular weight of 300-700Da, and a more preferred molecular weight range is 400-600Da, and the degree of polymerization x in the formula can be calculated based on the molecular weight.

[0009]

[0010] The rotation potential energy of the Si-O bond of vinyl double-terminated polysiloxane is low, the rotation steric hindrance to the side groups connected to the silicon atom is small, it has high flexibility, strong chain segment movement ability, and is particularly conducive to the conduction of sodium ions. However, the polarity of the Si-O bond is low, the ability to dissolve sodium salts and complex sodium ions is weak, and the film-forming property and mechanical properties are insufficient. The present invention significantly improves the sodium salt solubility and film-forming property of polysiloxane by copolymerizing with mercapto double-terminated polyethylene glycol, and the photocuring reactants are quickly formed into CS bonds by a crosslinking agent, thereby improving the mechanical properties of the composite film. By further controlling the molecular weight, an electrolyte composition that is conducive to coating processing is provided, and the photocuring rate is increased as much as possible within the desired range. In addition, adding an inorganic electrolyte composite to the composition can further improve the sodium ion conductivity.

[0011] Further, the crosslinking agent assists in the chain thiol-ene Click reaction of the long chains to form a polymer under the action of a photoinitiator, preferably a multi-thiol-terminated or multi-vinyl-terminated compound, which is beneficial to significantly improve the photocuring efficiency and the mechanical properties of the film. These compounds are selected from any one or a combination of more than one of, including but not limited to, pentaerythritol tetrakis(3-mercaptopropionate), trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetramethacrylate, ethoxylated trimethylolpropane triacrylate, and triallyl cyanurate, preferably pentaerythritol tetrakis(3-mercaptopropionate) or pentaerythritol tetramethacrylate. The molar ratio of all thiols and all vinyl groups of the thiol double-terminated polyethylene glycol, olefin double-terminated polysiloxane, and crosslinking agent is 1:1.

[0012] Further, the sodium salt includes any one or a combination of more than one of sodium hexafluorophosphate, sodium perchlorate, mono- or poly-fluorosubstituted sodium methanesulfonate, sodium bis(oxalato)borate, and sodium difluoro(oxalato)borate. Preferably, sodium hexafluorophosphate or sodium perchlorate is used. The addition amount of the sodium salt is 10-50 wt% of the total weight of the crosslinked polymer, and the preferred range is 20-50 wt%.

[0013] Further, the inorganic solid electrolyte includes any one or a combination of more than one of Na-β″-Al2O3, NASICON-type sodium ion conductors, and sulfide-type sodium ion conductors. Preferably, the inorganic solid electrolyte is selected from Na-β″-Al2O3 or NASICON-type sodium ion conductors. The addition amount of the inorganic solid electrolyte is 10-80 wt% of the total weight of the composition, and the preferred range is 25-55 wt%.

[0014] Further, the photoinitiator is selected from any one or a combination of more than one of, including but not limited to, benzoin, benzoin dimethyl ether, benzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-2-methylpropiophenone, and acetophenone. Preferably, benzoin dimethyl ether or 2,4-dihydroxybenzophenone is used. The addition amount of the photoinitiator is 1-4% of the total weight of the crosslinked polymer.

[0015] Further, the solvent is selected from any one or a combination of more than one of, including but not limited to, tetrahydrofuran, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, fluoroethylene carbonate, acetone, and ethyl acetate. Preferably, any one of tetrahydrofuran, ethylene carbonate, and dimethyl carbonate is used. The addition amount of the solvent is generally 100-300%, calculated based on the solid content in the composition being 100%.

[0016] Based on the above electrolyte composition, those skilled in the art can also add additives to the system as needed. The additives can be any one or a combination of dispersants, film-forming agents, film-forming flexibility improvers, defoamers, and wetting agents. The added additives account for 0-5% of the total weight of the polymer formed by the photocurable monomer and the crosslinking agent.

[0017] The composition of the present invention is prepared by stirring and dispersing mercapto-terminated polyethylene glycol, olefin-terminated polysiloxane, crosslinking agent, photoinitiator, sodium salt, inorganic solid electrolyte and solvent uniformly for standby.

[0018] The electrolyte composition is used for coating on the surface of the negative electrode slurry coating of the electrode sheet, and can replace the separator and electrolyte obtained by the existing in-situ thermal polymerization method or a commercial porous separator. The present invention is particularly suitable for sodium ion bipolar electrode sheets. Compared with lithium ion batteries, both the positive and negative electrodes of sodium ion batteries can use aluminum current collectors with low cost and good performance. The electrode sheet includes a current collector, a positive electrode slurry layer provided on one side of the current collector, a negative electrode slurry layer provided on the other side of the current collector, and an electrolyte film layer provided outside the negative electrode slurry layer.

[0019] Among them, the current collector is a foil made of any one or more of metals including but not limited to aluminum, nickel, and platinum, and can also be a conductive polymer. Aluminum foil is preferably used because of its cost advantage, light weight, good ductility, and it will not form an alloy with Na+. It is particularly suitable for or used in sodium ion bipolar electrode sheets. The thickness of the current collector is generally 10-20 μm. By further improving the tab, for example, increasing the tab cross-sectional area while keeping the overcurrent unchanged, a current collector with a thickness of only 3-9 μm can be provided.

[0020] The positive electrode slurry layer includes but is not limited to positive electrode active materials, conductive agents, binders, and inorganic sodium ion conductors. The binder is dissolved and dispersed in the solvent NMP, and the conductive agent, positive electrode active material, and inorganic sodium ion conductor are added in sequence, and stirred and dispersed uniformly to obtain the positive electrode slurry. Among them, the positive electrode active material is selected from layer oxide materials, polyanion compound materials, Prussian and its analogs, accounting for 80-99 wt% of the positive electrode slurry components. The conductive agent accounts for 0.5-10 wt%, and is selected from one or more of graphite, carbon black, carbon fiber, carbon nanotube, and graphene. The binder accounts for 0.5-10 wt%, and PVDF is selected. The inorganic sodium ion conductor accounts for 0.1-10 wt% of the positive electrode slurry components, and is selected from including but not limited to Na-β″-Al2O3, NASICON-type sodium ion conductors (Na 1+x Zr2P 3-x Si x O 12 (0≤x≤3)), sulfide-type sodium ion conductors (Na3PS4 type, Na3SbS4 type, Na 11Sn2PS 12 Any one or a combination of more than one of the following (the same below).

[0021] The negative electrode slurry layer includes a negative electrode active material, a binder, a dispersant, a conductive agent, and an inorganic sodium ion conductor. Dissolve and disperse the binder and the dispersant in deionized water, and sequentially add the conductive agent, the negative electrode active material, and the inorganic sodium ion conductor, and stir and disperse evenly to obtain the negative electrode slurry. Among them, the negative electrode active material is preferably hard carbon, accounting for 82-99 wt%; the conductive agent is selected from any one or a combination of more than one of, including but not limited to, graphite, carbon black, carbon fiber, carbon nanotube, and graphene, accounting for 0.01-5 wt%; the binder accounts for 1-10 wt%, and is selected from any one or a combination of more than one of, including but not limited to, polyacrylic acid-based, acrylate-based, polystyrene butadiene-based, and polyacrylonitrile-based copolymers; the dispersant is sodium carboxymethyl cellulose, accounting for 0-2%; the inorganic sodium ion conductor accounts for 0.1-10 wt%, and is selected from any one or a combination of more than one of, including but not limited to, Na-β″-Al2O3, NASICON-type sodium ion conductor (Na 1+x Zr2P 3-x Si x O 12 (0 ≤ x ≤ 3)), sulfide-type sodium ion conductor (Na3PS4 type, Na3SbS4 type, Na 11 Sn2PS 12 Any one or a combination of more than one of the following (the same below).

[0022] It should be noted that the improvement of the sodium ion battery electrode sheet described in the present invention compared with the prior art lies mainly in the electrolyte film layer formed by ultraviolet curing. For the above current collector, positive electrode slurry layer, and negative electrode slurry layer, those skilled in the art can selectively use the above materials and freely combine them without departing from the principle of the present invention, and all should be considered within the protection scope of the present invention.

[0023] The bipolar electrode sheet provided by the present invention can be used as an independent product, or can be made into a sodium ion battery by stacking or winding. Based on the bipolar battery structure of the present invention, electrons directly flow from the positive end of the current collector to the negative end. The thickness of the current collector is the electron transmission distance, and the electrode sheet area is the electron transmission area. Therefore, the ohmic resistance is much smaller than that of a battery in the form of stacking or winding, which is beneficial to improving the rate performance of the battery core.

[0024] Based on the principle of thiol-ethylene Click rapid photocuring, the present invention prepares a sodium ion battery electrode sheet with a novel organic-inorganic composite solid electrolyte film layer, replacing the traditional organic solvent electrolyte and polyolefin-based porous separator, which can improve and avoid problems such as electrolyte leakage, combustion, and short circuit caused by lithium / sodium dendrite piercing the separator in a liquid battery. The solid electrolyte film layer only needs to be cured under normal conditions (room temperature 25 °C, 0.96 mW / cm2 At the above light intensity), curing can be completed within 30 s, and the thickness after curing is 10 - 30 microns. The ionic conductivity of the solid electrolyte film layer at room temperature is not less than 10 -4 S / cm. At the same time, the electrolyte film layer has excellent film-forming properties and mechanical strength.

[0025] The electrolyte film layer of the present invention is directly coated on the surface of the electrode sheet, strengthening the solid-solid interface contact and reducing the battery interface impedance. Adding inorganic solid electrolyte powder to the positive and negative electrode slurries can further reduce the interface impedance between the positive and negative electrode sheets and the electrolyte film, improving the ionic conductivity and migration effect.

[0026] The bipolar stacked solid-state sodium-ion battery provided by the present invention eliminates the traditional tab structure, increases the electron transmission area, and can improve the rate performance of the battery cell. The size of the combined bipolar battery voltage depends on the number of stacked bipolar electrode sheets, and different battery voltages can be provided. Replacing the separator and organic electrolyte with a solid electrolyte film prevents ionic conduction between the layers of the bipolar electrode sheet, avoiding the problem of liquid junction internal short circuit caused by electrolyte overflow and improving the safety of the battery cell.

[0027] From a process perspective, the present invention optimizes the curing efficiency and further reduces the film layer thickness by optimizing parameters. The optimization of the component content of the organic matter ensures that it still has excellent film-forming properties and flexibility. The electrolyte composition solution only needs to be coated on the negative electrode side, which greatly simplifies the production process and improves the production efficiency compared with the prior art of coating both sides of the negative electrode sheet. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 FIG. 1 is a schematic structural diagram of a bipolar sodium-ion battery according to Embodiment 1 of the present invention, where a) is an electrolyte film layer formed by ultraviolet curing, b) is a negative electrode active material, c) is a current collector, and d) is a positive electrode active material. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The present invention will be further described below with reference to the drawings and specific embodiments. Unless otherwise specified, the following percentage units are all mass percentages.

[0030] Embodiment 1

[0031] This embodiment provides a bipolar solid-state sodium-ion electrode sheet, which is prepared by the following method:

[0032] 1. Prepare the sodium battery positive electrode paste

[0033] Dissolve and disperse the binder PVDF in N-methylpyrrolidone, and successively add conductive graphite, layered oxide, and NASICON, and stir and disperse evenly to obtain a positive electrode slurry. The components and dosages are as follows:

[0034]

[0035] Among them, the layered oxide is sodium nickel iron manganese oxide, and NASICON is Na2Zr2P2SiO 12 , and the solid content is 60%.

[0036] 2. Prepare the sodium battery negative electrode paste

[0037] Dissolve and disperse the polyacrylic acid copolymer and sodium carboxymethyl cellulose in deionized water, and then add conductive graphite, hard carbon and NASICON in sequence, and stir and disperse evenly to obtain the negative electrode paste. The components and dosages are as follows:

[0038]

[0039] Among them, the polyacrylic acid copolymer (the solid content of the polyacrylic acid binder is 12%, and the viscosity is about 15000 mPa·s), and NASICON is Na2Zr2P2SiO 12 , and the solid content is 50%.

[0040] 3. Prepare the current collector

[0041] The current collector is made of aluminum foil with a thickness of 7 microns.

[0042] 4. Prepare the ultraviolet-curable electrolyte composition

[0043]

[0044]

[0045] Mix the above components and disperse them in tetrahydrofuran solvent according to 2:3. Take a part of the prepared electrolyte composition and coat it on the test sample. After being irradiated with ultraviolet light of 0.96 mW / cm 2 , a 25-μm photocured electrolyte film layer is obtained after complete curing, and the detected ionic conductivity is 5.2×10 -4 S / cm.

[0046] 5. Preparation of bipolar electrode

[0047] Coat the positive electrode paste on one side of the current collector and the negative electrode paste on the other side, and dry it to obtain a bipolar sodium electrode sheet. Under room temperature conditions, directly coat the ultraviolet-curable electrolyte composition on the negative electrode side surface of the bipolar electrode sheet. After being irradiated with ultraviolet light of 0.96 mW / cm 2 , a rapid photocuring reaction occurs within 24 seconds to form a bipolar electrode sheet with an electrolyte film layer. As Figure 1 shown, stack the above-mentioned electrode sheets in the order of positive electrode facing negative electrode to obtain a bipolar solid-state sodium-ion battery.

[0048] Example 2

[0049] In this example, a bipolar solid-state sodium ion electrode sheet was prepared. The preparation of the current collector and the positive and negative electrode slurries was the same as in Example 1. The difference lies in the formulation of the ultraviolet-curable electrolyte composition, which includes the following components by mass percentage:

[0050] Component Mass percentage HS-PEG-SH, 500Da 4.5％ Vinyl-terminated polydimethylsiloxane, 500Da 30.5％ Pentaerythritol tetrakis(3-mercaptopropionate) 13％ Sodium hexafluorophosphate 19％ NASICON 32％ Benzoin dimethyl ether 1％

[0051] Mix the above components and disperse them in tetrahydrofuran solvent at a ratio of 2:3. Take a part of the prepared electrolyte composition and coat it on the test sample. After ultraviolet light irradiation at 0.96 mW / cm 2 and complete curing, a 25-μm photocured electrolyte film layer is obtained. The measured ionic conductivity is 4.4×10 -4 S / cm.

[0052] Coat the positive electrode slurry on one side of the current collector and the negative electrode slurry on the other side, and then dry to obtain a bipolar sodium electrode sheet. At room temperature, directly coat the ultraviolet-curable electrolyte composition on the negative electrode side surface of the bipolar electrode sheet. After ultraviolet light irradiation at 0.96 mW / cm 2 and complete curing within 26 seconds. Stack the above electrode sheets in the order of positive electrode facing negative electrode to obtain a bipolar solid-state sodium ion battery.

[0053] Example 3

[0054] In this example, a bipolar solid-state sodium ion electrode sheet was prepared. The preparation of the current collector and the positive and negative electrode slurries was the same as in Example 1. The difference lies in the formulation of the ultraviolet-curable electrolyte composition, which includes the following components by mass percentage:

[0055] Component Mass percentage HS-PEG-SH, 500Da 30.5％ Vinyl-terminated polydimethylsiloxane, 500Da 4.5％ Pentaerythritol tetramethacrylate 10.7％ Sodium hexafluorophosphate 23％ <![CDATA[Na-β″-Al2O3]]> 30.5％ Benzoin dimethyl ether 0.8％

[0056] It can be seen that the dosages of the visible mercapto-terminated polyethylene glycol and the olefin-terminated polysiloxane can be flexibly adjusted based on the different crosslinking agents selected. Mix the above components and disperse them in tetrahydrofuran solvent at a ratio of 2:3. Take a part of the prepared electrolyte composition and coat it on the test sample. After ultraviolet light irradiation at 0.96 mW / cm 2 and complete curing, a 23-μm photocured electrolyte film layer is obtained. The measured ionic conductivity is 4.1×10 -4 S / cm. It can be seen that too high a sodium salt content will instead lead to a decrease in ionic conductivity.

[0057] Coat the positive electrode slurry on one side of the current collector and the negative electrode slurry on the other side, and then dry to obtain a bipolar sodium electrode sheet. At room temperature, directly coat the ultraviolet-curable electrolyte composition on the negative electrode side surface of the bipolar electrode sheet. After ultraviolet light irradiation at 0.96 mW / cm 2Upon ultraviolet light irradiation, it is completely cured within 26 seconds. Stack the above-mentioned electrode sheets in sequence according to the principle of positive electrode facing negative electrode to obtain a bipolar solid-state sodium-ion battery.

[0058] Example 4

[0059] In this example, a bipolar solid-state sodium-ion electrode sheet is prepared. The preparation of the current collector and the positive and negative electrode slurries is the same as that in Example 1, and the difference lies in the formulation of the ultraviolet-curable electrolyte composition, which includes the following components by mass percentage:

[0060] Component Mass percentage HS-PEG-SH, 500Da 5.8％ Vinyl-terminated polydimethylsiloxane, 500Da 40.8％ Pentaerythritol tetramethacrylate 17.1％ Sodium hexafluorophosphate 19％ <![CDATA[Na-β″-Al2O3]]> 16％ Benzoin dimethyl ether 1.3％

[0061] Mix the above components and disperse them in tetrahydrofuran solvent according to a ratio of 2:3. Take a part of the prepared electrolyte composition and coat it on the test sample. After ultraviolet light irradiation at 0.96 mW / cm 2 After complete curing, a photocured electrolyte film layer with a thickness of 28 μm is obtained, and the detected ionic conductivity is 2.8×10 -4 S / cm.

[0062] Coat the positive electrode slurry on one side of the current collector and the negative electrode slurry on the other side, and dry it to obtain a bipolar sodium electrode sheet. At room temperature, directly coat the ultraviolet-curable electrolyte composition on the negative electrode side surface of the bipolar electrode sheet. After ultraviolet light irradiation at 0.96 mW / cm 2 Upon ultraviolet light irradiation, it is completely cured within 28 seconds. Stack the above-mentioned electrode sheets in sequence according to the principle of positive electrode facing negative electrode to obtain a bipolar solid-state sodium-ion battery.

[0063] Example 5

[0064] In this example, a bipolar solid-state sodium-ion electrode sheet is prepared. The preparation of the current collector and the positive and negative electrode slurries is the same as that in Example 1, and the difference lies in the formulation of the ultraviolet-curable electrolyte composition, which includes the following components by mass percentage:

[0065] Component Mass percentage HS-PEG-SH, 5000Da 29％ Vinyl-terminated polydimethylsiloxane, 5000Da 10％ Pentaerythritol tetramethacrylate 0.7％ Sodium hexafluorophosphate 19.8％ <![CDATA[Na-β″-Al2O3]]> 39.7％ Benzoin dimethyl ether 0.8％

[0066] Mix the above components and disperse them in a mixed solvent of ethylene carbonate / dimethyl carbonate (1:1) according to a ratio of 2:3. Take a part of the prepared electrolyte composition and coat it on the test sample. After ultraviolet light irradiation at 0.96 mW / cm 2 Upon ultraviolet light irradiation, it is found that it cannot be cured even after long-term irradiation.

[0067] Example 6

[0068] In this example, a bipolar solid-state sodium-ion electrode sheet is prepared. The preparation of the current collector and the positive and negative electrode slurries is the same as that in Example 1, and the difference lies in the formulation of the ultraviolet-curable electrolyte composition, which includes the following components by mass percentage:

[0069] Component Mass percentage HS-PEG-SH, 500Da 35.5％ Vinyl-terminated polydimethylsiloxane, 500Da 5.1％ Pentaerythritol tetramethacrylate 12.4％ Sodium perchlorate 10.6％ <![CDATA[Na-β″-Al2O3]]> 35.3％ Benzoin dimethyl ether 1.1％

[0070] Mix the above components and disperse them in tetrahydrofuran solvent at a ratio of 2:3. Take a part of the prepared electrolyte composition and coat it on the test sample. After being irradiated with ultraviolet light at 0.96 mW / cm 2 and completely cured, a photocured electrolyte film layer with a thickness of 26 μm is obtained. The ionic conductivity is detected to be 3.8×10 -4 S / cm.

[0071] Coat the positive electrode paste on one side of the current collector and the negative electrode paste on the other side, and then dry it to obtain a bipolar sodium electrode sheet. At room temperature, directly coat the ultraviolet-curable electrolyte composition on the negative electrode side surface of the bipolar electrode sheet, and irradiate it with ultraviolet light at 0.96 mW / cm 2 and completely cure it within 28 seconds. Stack the above electrode sheets in sequence according to the principle of positive electrode facing negative electrode to obtain a bipolar solid-state sodium ion battery.

[0072] The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A sodium-ion battery electrode with a photocurable electrolyte coating, characterized in that: An electrolyte film layer formed by ultraviolet curing of an electrolyte composition is provided on the negative electrode of the electrode plate. The electrolyte composition includes: mercapto-terminated polyethylene glycol, olefin-terminated polysiloxane, a crosslinking agent, a photoinitiator, a sodium salt, an inorganic solid electrolyte, and a solvent.

2. The sodium ion battery electrode sheet with a photocurable electrolyte coating according to claim 1, characterized in that, The average molecular weight of the mercapto-terminated polyethylene glycol is 200-1000 Da.

3. The sodium ion battery electrode sheet with a photocurable electrolyte coating according to claim 1, characterized in that: The average molecular weight of the olefin-terminated polysiloxane is 300-700 Da.

4. The sodium ion battery electrode with a photocurable electrolyte coating according to claim 1, characterized in that: The crosslinking agent includes a small molecule carbon-based compound with an ethylene end and / or a mercapto end. The molar ratio of all mercapto groups and all vinyl groups of the mercapto-terminated polyethylene glycol, olefin-terminated polysiloxane, and crosslinking agent is 1:

1.

5. The sodium ion battery electrode with a photocurable electrolyte coating according to claim 1, characterized in that: The inorganic solid electrolyte includes any one or a combination of more than one of Na-β″-Al2O3, NASICON-type sodium ion conductors, and sulfide-type sodium ion conductors.

6. The sodium ion battery electrode sheet with a photocurable electrolyte coating according to claim 1, wherein: The solvent is any one or a combination of more than one of tetrahydrofuran, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, fluorinated ethylene carbonate, acetone, and ethyl acetate.

7. A sodium-ion battery electrode with a photocurable electrolyte coating according to any one of claims 1-6, characterized in that: The thickness of the electrolyte membrane layer is 10 - 30 μm, and its ionic conductivity at room temperature is not less than 10 -4 S / cm.

8. A sodium ion battery electrode sheet with a photocurable electrolyte coating according to claim 7, characterized in that: The electrode plate is a bipolar electrode plate, which includes a current collector, a positive electrode paste layer provided on one side of the current collector, a negative electrode paste layer provided on the other side of the current collector, and an electrolyte film layer provided outside the negative electrode paste layer; The positive electrode paste layer includes a positive electrode active material, a conductive agent, a binder, and an inorganic sodium ion conductor. The negative electrode paste layer includes a negative electrode active material, a conductive agent, a binder, and an inorganic sodium ion conductor.

9. The sodium ion battery electrode sheet with a photocurable electrolyte coating according to claim 8, characterized in that: The current collector is a foil made of any one or a combination of more than one of aluminum, nickel, and platinum.

10. A solid-state sodium-ion battery, characterized in that: The sodium ion battery electrode plate according to any one of claims 1-9 is made by stacking or winding.

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