A supercapacitor and a method for manufacturing the same

Abstract

The present invention discloses a method for making a supercapacitor, the method comprising: providing two electrodes, the electrodes being self-supporting metal grids or substrate-supported metal grids; depositing the same or different active materials on the two electrodes, the active materials at least covering the surface of one side of the electrodes; immersing the two electrodes deposited with the active materials in a gel electrolyte; taking out the two electrodes immersed in the gel electrolyte and bonding them together to form a sandwich structure; after curing, obtaining a supercapacitor. The present invention also discloses a supercapacitor, comprising two electrodes, a gel electrolyte disposed between the two electrodes, the same or different active materials being deposited on the two electrodes, wherein the active materials at least cover the surface of one side of the electrodes, and the electrodes being self-supporting metal grids or substrate-supported metal grids. The supercapacitor made by the above method has good flexibility, high light transmittance, can be attached to any complex structure, and has a simple manufacturing process, strong controllability, and is easy to implement.

Description

Technical Field

[0001] The present invention relates to the technical field of capacitors, and in particular to a supercapacitor and a manufacturing method thereof. Background Art

[0002] The trend of the rise of the flexible electronics industry has become increasingly clear. Flexible displays, flexible lighting, flexible solar cells, flexible sensors and other products have gradually moved from the laboratory to the market. The development of integrated wearable and portable devices has stimulated the demand for energy storage devices, especially in the field of flexible and transparent devices, such as wearable displays, smart windows, and electronic skin. Under this industry trend, transparent flexible energy storage devices have huge market value and have become one of the research hotspots in the field of flexible electronics.

[0003] Flexible transparent electrodes are the basis of many flexible optoelectronic products. Therefore, flexible transparent electrodes will become a strategic material for flexible optoelectronic products. Energy storage devices, such as supercapacitors and batteries, are greatly affected by electrodes in terms of overall device transmittance, flexibility and energy storage capacity. Carbon materials, such as carbon nanotubes and graphene, are limited by their own conditions, have limited energy storage capacity, and have low transmittance, which limits their applications. Flexible and transparent supercapacitor electrodes are prepared by depositing activated materials (manganese oxide, cobalt oxide, etc.) on flexible transparent current collectors, thereby further assembling solid-state supercapacitors.

[0004] The preceding description is intended to provide general background information and does not necessarily constitute prior art. Summary of the invention

[0005] The object of the present invention is to provide a supercapacitor with good flexibility and a method for manufacturing the same.

[0006] The present invention provides a method for manufacturing a supercapacitor, the method comprising:

[0007] The method includes:

[0008] providing two electrodes, the electrodes being self-supporting metal grids;

[0009] Depositing the same or different active materials on the two electrodes, wherein the active materials at least cover the surface of one side of the electrode;

[0010] immersing the two electrodes on which the active materials are deposited into a gel electrolyte;

[0011] Taking out the two electrodes immersed in the gel electrolyte and sticking them together to form a sandwich structure;

[0012] After curing, the supercapacitor is obtained.

[0013] In one embodiment, when the electrode is a self-supporting metal grid, the specific steps of preparing the self-supporting metal grid include:

[0014] providing a substrate;

[0015] Coating a layer of photoresist on the substrate to form a photoresist layer;

[0016] A mesh grid groove is prepared on the photoresist layer;

[0017] Filling the conductive material into the grid groove by scraping and / or selective electrodeposition to form a metal grid in the grid groove;

[0018] The metal grid is separated from the photoresist layer and the substrate to obtain the self-supporting metal grid.

[0019] In one embodiment, the metal grid has a grid period of 10um-300um and a grid line width of 0.5um-10um.

[0020] In one embodiment, after the step of providing two electrodes and before the step of depositing active materials, the step further includes depositing a layer of metal on the metal grid, wherein the metal is gold.

[0021] In one embodiment, the gel electrolyte is a mixture of lithium chloride, polyvinyl alcohol and water.

[0022] In one embodiment, the active material is manganese oxide and / or cobalt oxide. When the active material is manganese oxide, the manganese oxide is deposited by high temperature deposition to adjust the surface morphology of the manganese oxide.

[0023] The present invention also provides a supercapacitor, comprising two electrodes, a gel electrolyte arranged between the two electrodes, the same or different active materials deposited on the two electrodes, wherein the active material at least covers the surface of one side of the electrode, and the electrode is a self-supporting metal grid or a substrate-supported metal grid.

[0024] In one embodiment, the self-supporting metal grid is a separate metal grid; and the substrate-supported metal grid includes a substrate and a metal grid.

[0025] In one embodiment, the metal grid is a plurality of periodically arranged polygons or circles or random patterns.

[0026] In one embodiment, the period of the metal grid is 10um-300um; the grid line width is 0.5um-10um.

[0027] In one embodiment, the active material is manganese oxide and / or cobalt oxide.

[0028] The method for manufacturing a supercapacitor provided by the present invention comprises immersing the two electrodes in the gel electrolyte and bonding the two electrodes together to form a sandwich structure. The structure has good flexibility and high light transmittance and can be attached to any complex structure. The manufacturing process is simple, controllable and easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a flowchart of the steps of a method for manufacturing a supercapacitor according to an embodiment of the present invention;

[0030] Figure 2 for Figure 1 Specific step flow chart of step S1;

[0031] Figures 3a to 3e for Figure 2 Process flow chart of

[0032] Figure 4 for Figure 1 A flowchart of the specific steps of another method of step S1;

[0033] Figure 5 A schematic diagram of the structure of a supercapacitor according to an embodiment of the present invention;

[0034] Figure 6 FIG. 1 is a schematic structural diagram of a supercapacitor according to another embodiment of the present invention. DETAILED DESCRIPTION

[0035] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0036] Please refer to Figure 1 , a method for manufacturing a supercapacitor provided in an embodiment of the present invention, the method comprising:

[0037] S1: providing two electrodes, wherein the electrodes are self-supporting metal grids;

[0038] S2: depositing the same or different active materials on the two electrodes, wherein the active materials at least cover the surface of one side of the electrode;

[0039] S3: immersing the two electrodes deposited with active materials into a gel electrolyte;

[0040] S4: taking out the two electrodes immersed in the gel electrolyte and bonding them together to form a sandwich structure;

[0041] S5: After curing, the supercapacitor is obtained.

[0042] In step S1 , the two electrodes may be self-supporting metal grids at the same time, and the self-supporting metal grid is a separate metal grid.

[0043] In step S2, the active material is manganese oxide and / or cobalt oxide. When depositing the active material, when the active material is manganese oxide, depositing manganese oxide by high temperature deposition can adjust the surface morphology of manganese oxide and increase the surface area. Before depositing the active material, a layer of gold can be deposited on the electrode, and then the active material can be deposited, which can improve the conductivity of the electrode, and the energy storage capacity of the assembled solid-state supercapacitor is greatly improved.

[0044] It should be noted that when the active materials deposited on the metal grid are the same, a symmetrical capacitor can be formed; when the active materials deposited on the metal grid are different, an asymmetrical capacitor is formed.

[0045] In step S4, the electrode can be completely immersed in a gel electrolyte, wherein the gel electrolyte is transparent and is made by mixing lithium chloride, polyvinyl alcohol and water in a certain proportion.

[0046] Providing an electrode in step S1 includes a method for preparing an electrode. When the electrode is a self-supporting metal grid, such as Figure 2 , Figures 3a to 3e As shown, the specific steps of preparing the self-supporting metal grid include:

[0047] S11: providing a substrate 1;

[0048] S12: coating a layer of photoresist on the substrate 2 to form a photoresist layer 2;

[0049] S13: preparing a grid groove 21 on the photoresist layer 2;

[0050] S14: filling the grid groove 21 with a conductive material by selective electrodeposition to form a metal grid 3 in the grid groove 21;

[0051] S15: separating the metal grid 3 from the photoresist layer 2 and the base layer 1 to obtain the self-supporting metal grid 3;

[0052] In step S13, a grid groove 21 of a desired pattern is formed on the photoresist layer 2 by embossing. When electrodeposition is required later, the substrate 1 needs to be conductive, so the bottom of the grid groove 21 needs to expose the surface of the conductive substrate 1 to facilitate the subsequent electrodeposition of conductive materials.

[0053] In other embodiments, the grid grooves 21 are formed on the photoresist layer 2 by exposure and development.

[0054] In step S14, the growth conditions of the electrochemically deposited metal are adjusted, such as by overpotential pulse deposition, to obtain a metal grid 3 with a micro-nano surface morphology. In other embodiments, the conductive paste prepared from the conductive paste material is filled into the grid groove 21 by scraping to obtain the metal grid 3.

[0055] The electrode prepared according to the above method has the advantages of high light transmittance (>90%), small thickness (10-1um), strong flexibility, high temperature resistance, etc. The pattern of the metal grid is not limited, and can be polygonal or circular or other random patterns; the conductive material is gold, silver, copper, nickel or other metals. The preparation method of the flexible transparent electrode provided by the present invention has a simple process, can be mass-produced in large format, and is suitable for large-scale production and application.

[0056] The supercapacitor prepared by using the electrode of the present invention has high light transmittance, which is between 80% and 95%; it has excellent mechanical properties, is ultra-thin, and can be attached to any object with complex structure.

[0057] In the present invention, the capacitance, transmittance and flexibility of supercapacitors prepared by different metal grid materials, grid patterns and active materials are all different. Below, the method for making the supercapacitor of the present invention will be described in detail in combination with the specific implementation methods. It should be pointed out that the electrodes mentioned below can be understood as current collectors in batteries (current collectors refer to structures or parts that collect current, and in lithium-ion batteries they mainly refer to metal foils, such as copper foil and aluminum foil; in the present invention, they can refer to structures with metal grids prepared by conductive materials in the above method).

[0058] First embodiment

[0059] In this embodiment, the electrode is a self-supporting metal grid. Specifically, first, a photoresist is spin-coated on a conductive substrate ITO (indium tin oxide) glass; a patterned photolithography machine is used to expose a gourd-type grid pattern on the photoresist layer; development is performed in a developer to reveal the grid groove, and the ITO substrate at the bottom of the groove is fully developed to expose the ITO substrate to form a patterned conductive layer; selective electrodeposition is used to induce and constrain the growth of metal nickel in the groove to form a nickel grid electrode; excess photoresist on the ITO surface is removed, and the exposed nickel grid is directly peeled off to obtain a gourd-type self-supporting metal grid with a period of 200um, a line width of 6um, a thickness of 1.5-5um, and a transmittance of 84%. Manganese oxide is deposited on the electrode, and the electrolyte for depositing manganese oxide is 0.05mol / L MnSO4+0.05mol / L CH3COONa, and the deposition conditions are (constant voltage method, constant voltage 0.92V, deposition 100s), and the transmittance decreases by 0.48% after depositing manganese oxide.

[0060] The two gourd-shaped self-supporting metal grids are immersed in PVA / LiCl electrolyte, and the electrolyte preparation method is the same as above. After being completely soaked, they are taken out, and the two self-supporting electrodes are bonded together to form a sandwich structure, and after solidification, a solid-state sandwich structure supercapacitor is obtained.

[0061] The supercapacitor constructed by this scheme does not require substrate support, has a thickness of only 20um, and a transmittance of 80%, achieving the preparation of ultra-thin and high-transmittance capacitors with a capacitor capacity of 10mF / cm 2 .

[0062] Second embodiment

[0063] In this embodiment, the electrode is a self-supporting metal grid. A layer of gold is first deposited on the metal grid, and then an active material is deposited, and finally an electrolyte is added to assemble a solid-state supercapacitor. Specifically, first, a photoresist is spin-coated on a conductive substrate ITO (indium tin oxide) glass; a hexagonal grid pattern is exposed on the photoresist layer using a graphic lithography machine; development is performed in a developer to reveal the grid grooves, and the ITO substrate at the bottom of the groove is fully developed to form a graphic conductive layer; selective electrodeposition is used to induce and constrain the growth of metal nickel in the grooves to form a nickel grid electrode; excess photoresist on the ITO surface is removed, and the exposed nickel grid is directly peeled off to obtain a self-supporting hexagonal nickel grid with a period of 200um, a line width of 5um, a thickness of 4um, and a transmittance of 92%. A thin layer of gold is first deposited on the electrode (constant voltage method, -0.5V, 5s; 0V, 100s), and then manganese oxide is deposited (constant current method, 5mA / cm 2 , 100s), the electrode transmittance is 89%. The two self-supporting electrodes are immersed in PVA / LiCl electrolyte (the electrolyte preparation method is the same as above), taken out after complete immersion, and the two self-supporting electrodes are bonded together to form a sandwich structure, and then cured. A solid-state sandwich structure supercapacitor is obtained. After being assembled into a solid-state capacitor, the transmittance is 83.6%. Using cyclic voltammetry to test, the area capacitance is 21.25mF / cm at a scan rate of 5mV / s. 2 Manganese oxide was directly deposited on the nickel electrode to serve as a supercapacitor electrode and assembled into a solid-state capacitor. The area capacitance was 14.86 mF / cm at a scan rate of 5 mV / s. 2 Compared with depositing manganese oxide directly on the nickel electrode, depositing a thin layer of gold first and then depositing manganese oxide can greatly improve the energy storage capacity of the capacitor.

[0064] Third embodiment

[0065] In this embodiment, the electrode preparation is the same as in the second embodiment. By adjusting the growth conditions of the electrochemically deposited metal, a micro-nano branch-like and coral-like surface morphology is obtained on the original electrode grid. By in-situ overpotential pulse deposition, a branch-like nickel structure is grown. By adjusting the morphology of nickel and then depositing MnO2, the specific surface area is increased, thereby improving the capacitance.

[0066] A thin layer of gold was first deposited on the self-supporting electrode (constant voltage method, -0.5V, 5s; 0V, 100s) to increase the nucleation point for the subsequent microstructure deposition; then the microstructure metal nickel was deposited by the overpotential pulse method. The electrolyte for depositing the dendritic microstructure nickel was 0.1mKCl+0.1mM HAuCl4+0.12MNiSO4·6H2O+1.5M NH4Cl+100mg / 300mL polyethyleneglycol (PEG) 4000. The deposition conditions were: the current was 0.25mA / cm 2 Deposition time 0.05s, current 0mA / cm 2 Deposition was performed for 0.05s, which was regarded as one cycle and repeated 200 times. Thus, the dendritic nickel structure was evenly deposited around the self-supporting mesh bars to obtain a microstructured self-supporting electrode. Manganese oxide was then deposited (constant voltage method, 0.9V, 50s), and the electrode transmittance was 80%. The two self-supporting microstructure electrodes were immersed in a PVA / LiCl electrolyte. The electrolyte preparation method was the same as above. After complete immersion, they were taken out and the two self-supporting electrodes were bonded together to form a sandwich structure, and then cured. A solid-state sandwich structure supercapacitor was obtained. After being assembled into a solid-state capacitor, the transmittance was 77%. Using cyclic voltammetry to test, the area capacitance was 1.4mF / cm at a scan rate of 0.1V / s. 2 Therefore, by continuing to deposit an appropriate amount of active material on the surface of the dendritic nickel structure, the resulting flexible transparent supercapacitor electrode has a high specific surface area, which greatly increases the contact area between the active material and the electrolyte, accelerates ion migration, and significantly improves the capacity of the prepared solid-state supercapacitor.

[0067] Fourth embodiment

[0068] In this embodiment, the preparation of the self-supporting hexagonal electrode is the same as that of Example 2. The surface morphology of manganese oxide is regulated by high-temperature deposition of manganese oxide to increase the specific surface area and increase the capacitance. First, a thin layer of gold (-0.5V, 5s; 0V, 100s) is deposited on the self-supporting nickel mesh to provide nucleation points and enhance the conductivity of the nickel mesh, and then manganese oxide is deposited at a high temperature (25-85°C). Here, the nickel mesh has a period of 200um, a line width of 5um, and a thickness of 4um.

[0069] At a low temperature (25°C), the manganese oxide deposition is relatively dense and has a small and flat structure. As the temperature increases, three-dimensional manganese oxide spheres are formed on the surface of the nickel mesh with a prominent structure. The manganese oxide obtained by deposition at 75°C for 900s has the most prominent morphology and the largest specific surface area.

[0070] When the temperature is higher, the deposited manganese oxide load is greater, the electrode line width increases, and the transmittance decreases. As the temperature changes, the single electrode capacity is the largest at 75°C, so 75°C is the optimal deposition temperature.

[0071] At 75°C, manganese oxide was deposited for 300s, 600s, and 900s, respectively. At 300s, the manganese oxide spheres formed were about 1um. When the deposition continued to last for 900s, the manganese oxide spheres increased to 5-8um.

[0072] The three-dimensional manganese oxide electrode was assembled into a symmetrical solid-state supercapacitor, that is, the three-dimensional manganese oxide electrode was immersed in the PVA / LiCl electrolyte, taken out after being completely soaked, and the two electrodes were bonded together to form a sandwich structure. After solidification, a solid-state sandwich structure supercapacitor was obtained. The supercapacitor prepared by this method had an area capacitance of 80mF / cm at a scan rate of 5mV / s. 2 , the capacity is greatly improved compared with the planar structure supercapacitor. In this embodiment, the preparation of three-dimensional microstructure active material morphology can be achieved by adjusting the temperature of the electrolyte when depositing the active material, thereby increasing the specific surface area of ​​the active material and improving the energy storage capacity of the supercapacitor.

[0073] Please refer to Figure 5 and Figure 6 The present invention also provides a supercapacitor, comprising two electrodes 3, a gel electrolyte 6 disposed between the two electrodes 3, and the same or different active materials 5 deposited on the two electrodes 3. The active material 5 at least covers the surface of one side of the electrode 3, and the electrode 3 is a self-supporting metal grid or a substrate-supported metal grid.

[0074] When the electrode is a substrate supporting a metal grid, such as Figure 4 As shown, the specific steps of preparing the substrate supporting metal grid include:

[0075] S101: providing a substrate;

[0076] S102: coating a layer of photoresist on the substrate to form the photoresist layer;

[0077] S103: preparing a grid groove on the photoresist layer;

[0078] S104: Filling the conductive material into the grid groove by scraping and / or selective electrodeposition to obtain the substrate-supported metal grid.

[0079] The photoresist in the substrate supporting metal grid obtained in step S104 may be retained or removed using a cleaning solution.

[0080] The specific preparation steps of the substrate-supported metal grid include: first, spin-coating photoresist on a glass substrate, using a graphic lithography machine to expose a hexagonal grid pattern on the photoresist layer; developing in a developer to reveal hexagonal grid microgrooves. Ag nano-ink (solid content 70%, viscosity 25cps, particle size distribution 200-300nm) is locally filled in the hexagonal grooves by scraping technology, sintered at 120°C for 20 minutes to solidify, and the surface is cleaned and wiped with alcohol to remove the Ag particles remaining on the surface to prepare a hexagonal Ag grid electrode. The micro-groove structure obtained by development can also be copied to a soft mold, and the high molecular polymer used in the soft mold is polyurethane acrylate (PUA). Then, the prepared mold is used to perform nanoimprinting on a PET substrate to construct a hexagonal structure groove. Then, Ag nano-ink (solid content 70%, viscosity 25cps, particle size distribution 200-300nm) was filled into the hexagonal grooves by scraping technology, sintered at 120℃ for 20 minutes to solidify, and the surface was cleaned and wiped with alcohol to remove the residual Ag particles on the surface to prepare the hexagonal Ag grid electrode. The metal grid has a period of 100um, a line width of 4um, a thickness of 3um, a light transmittance of 85%, and a square resistance of 1.0Ω / cm 2 .

[0081] In this embodiment, if Figure 5 As shown, the electrode 3 is a self-supporting metal grid and does not include a substrate. Figure 6 As shown, the electrode 3 is a substrate-supported metal grid, including a substrate 31, a photoresist layer disposed on the surface of the substrate 31, and a metal grid 33 embedded in the photoresist layer.

[0082] The metal grid is a plurality of periodically arranged polygons, circles or random patterns, with a period of 10um-300um; the grid line width is 0.5um-10um.

[0083] The active material is manganese oxide and / or cobalt oxide. When the electrode is a self-supporting metal grid, the active material wraps the metal grid; when the electrode is a substrate-supported metal grid, the active material may not cover the substrate but only covers the metal grid.

[0084] The gel electrolyte is transparent and is made by mixing lithium chloride, polyvinyl alcohol and water in a certain proportion.

[0085] The method for preparing a supercapacitor provided by the present invention has a simple process, and the steps can be arbitrarily controlled and easily implemented. The electrodes prepared therein have high light transmittance, strong flexibility, and outstanding electrochemical performance. The supercapacitors and batteries prepared thereby are also ultra-thin and highly light transmittance, and can be applied to the field of flexible transparent electronics, especially wearable devices that require high light transmittance and high flexibility.

[0086] In the accompanying drawings, the sizes and relative sizes of layers and regions are exaggerated for clarity. It should be understood that when an element, such as a layer, region, or substrate, is referred to as being "formed on," "disposed on," or "located on" another element, the element may be disposed directly on the other element, or there may be intervening elements. Conversely, when an element is referred to as being "formed directly on" or "disposed directly on" another element, there are no intervening elements.

[0087] In this document, unless otherwise specified or limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0088] In this document, the directions or positional relationships indicated by terms such as "up", "down", "front", "back", "left", "right", "top", "bottom", "inside", "outside", "vertical", and "horizontal" are based on the directions or positional relationships shown in the accompanying drawings and are only for the clarity of expressing the technical solutions and the convenience of description, and therefore should not be understood as limitations of the present invention.

[0089] As used herein, unless otherwise specified, “plurality” or “several” means two or more.

[0090] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0091] In this document, the terms "comprises," "comprising," or any other variations thereof, are intended to cover a non-exclusive inclusion of elements other than those listed and may also include additional elements not expressly listed.

[0092] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for manufacturing a supercapacitor, characterized in that: The method includes: providing two electrodes, the electrodes being self-supporting metal grids; Depositing the same or different active materials on the two electrodes, wherein the active materials cover at least one side of the surface of the electrode; the active materials are manganese oxide and / or cobalt oxide. When depositing the active materials, when the active material is manganese oxide, depositing the manganese oxide by high-temperature deposition can adjust the surface morphology of the manganese oxide and increase the surface area. Before depositing the active material, a layer of gold may be deposited on the electrode, and then the active material may be deposited; immersing the two electrodes on which the active materials are deposited into a gel electrolyte; Taking out the two electrodes immersed in the gel electrolyte and sticking them together to form a sandwich structure; After curing, a supercapacitor is obtained; When the electrode is a self-supporting metal grid, the specific steps of preparing the self-supporting metal grid include: providing a substrate; Coating a layer of photoresist on the substrate to form a photoresist layer; Preparing a grid groove on the photoresist layer; Filling the conductive material into the grid groove by scraping and / or selective electrodeposition to form a metal grid in the grid groove; The metal grid is separated from the photoresist layer and the substrate to obtain the self-supporting metal grid; the grid period of the metal grid is 10um-300um; and the grid line width is 0.5um-10um.

2. The method for manufacturing a supercapacitor according to claim 1, wherein: After the step of providing two electrodes and before the step of depositing active materials, the method further includes depositing a layer of metal on the metal grid, wherein the metal is gold.

3. The method for manufacturing a supercapacitor according to claim 1, wherein: The gel electrolyte is a mixture of lithium chloride, polyvinyl alcohol and water.

4. The method for manufacturing a supercapacitor according to claim 1, wherein: The active material is manganese oxide and / or cobalt oxide. When the active material is manganese oxide, the manganese oxide is deposited by high-temperature deposition to adjust the surface morphology of the manganese oxide.

5. A supercapacitor, characterized in that: It comprises two electrodes and a gel electrolyte arranged between the two electrodes, wherein the gel electrolyte is a mixture of lithium chloride, polyvinyl alcohol and water, and the same or different active materials are deposited on the two electrodes, wherein the active materials are manganese oxide and / or cobalt oxide, wherein the active materials at least cover the surface of one side of the electrode, and the electrode is a self-supporting metal grid, which is a separate metal grid, and the metal grid is a plurality of periodically arranged polygonal or circular or random patterns, wherein the period of the metal grid is 10um-300um; and the grid line width is 0.5um-10um.

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