Bending structure secondary battery and method for manufacturing the same

Abstract

The present application provides a secondary battery. The secondary battery can include a positive electrode, a solid electrolyte, and a negative electrode, form a laminated structure in which the positive electrode and the solid electrolyte are laminated, bend the laminated structure, thereby forming a bending region between the laminated structure, and form the negative electrode in the bending region.

Description

Technical Field

[0001] This application relates to secondary batteries and methods for preparing them, and more specifically, to secondary batteries with curved structures and methods for preparing them. Background Technology

[0002] With the rapid growth of secondary batteries in small devices and home appliances, and even in medium-to-large-scale high-energy applications such as electric vehicles and energy storage systems (ESS), the market value of the secondary battery industry is projected to grow from approximately US$22 billion in 2018 to approximately US$118 billion by 2025. Therefore, in order to use secondary batteries as a medium for medium-to-large-scale energy storage, they need to possess significantly improved price competitiveness, energy density, and stability compared to current levels.

[0003] Based on these technological requirements, various electrodes for secondary batteries are being developed.

[0004] For example, Korean Patent Publication No. 10-2019-0139586 discloses an electrode for a lithium-air battery, which includes carbon nanotubes and RuO2 deposited on the surface of the carbon nanotubes. The RuO2 is deposited at defect sites on the surface of the carbon nanotubes, and the particle size of the RuO2 is 1.0 nm to 4.0 nm. The RuO2 inhibits carbon decomposition at the defect sites on the surface of the carbon nanotubes and promotes the decomposition of Li2O2 formed on the surface of the carbon nanotubes. Summary of the Invention

[0005] Technical issues

[0006] The technical problem to be solved by this application is to provide a secondary battery with a curved structure and a method for its preparation.

[0007] Another technical problem to be solved by this application is to provide a secondary battery with a curved structure that is inexpensive to manufacture and has a simple manufacturing process, as well as a method for manufacturing the same.

[0008] Another technical problem to be solved by this application is to provide a secondary battery with a curved structure that improves charge and discharge capacity and a method for preparing the same.

[0009] Another technical problem to be solved by this application is to provide a secondary battery with a bending structure having a long lifespan and high stability, and a method for preparing the same.

[0010] The technical problems to be solved by this application are not limited to those mentioned above.

[0011] Technical solution

[0012] To address the aforementioned technical problems, this application provides a secondary battery.

[0013] According to one embodiment, the secondary battery may include a positive electrode, a solid electrolyte, and a negative electrode, forming a stacked structure of the positive electrode and the solid electrolyte. The stacked structure is bent to form a bent region between the stacked structures, and the negative electrode is formed in the bent region.

[0014] According to one embodiment, the inner surface of the aforementioned curved region may include the aforementioned solid electrolyte, and the aforementioned negative electrode is in contact with the aforementioned solid electrolyte.

[0015] According to one embodiment, the stacked structure formed by the positive electrode and the solid electrolyte and the negative electrode formed in the bending region can be defined as a unit cell. Multiple unit cells are formed and stacked on top of each other, such that the positive electrodes included in adjacent unit cells are in contact with each other.

[0016] According to one embodiment, the stacked plurality of unit cells can be defined as a cellular structure, and a plurality of such cellular structures are formed, wherein the plurality of such cellular structures are arranged such that the positive electrode included in the cellular structure is in contact with each other.

[0017] According to one embodiment, the stacked structure formed by the positive electrode and the solid electrolyte and the negative electrode formed in the bending region can constitute a unit cell. Multiple unit cells are formed and stacked on each other, such that the positive electrodes included in adjacent unit cells are adjacent to each other. The secondary battery may also include a gas diffusion layer disposed between adjacent unit cells.

[0018] According to one embodiment, the stacked plurality of unit cells and the gas diffusion layer disposed between the unit cells can be defined as a cellular structure, wherein the cellular structure is configured such that the positive electrode contacts each other.

[0019] According to one embodiment, the aforementioned stacked structure can be bent toward a first side and a second side opposite to the first side, forming the aforementioned negative electrode in a first bending region bending toward the first side, and in a second bending region bending toward the second side, the aforementioned positive electrodes of the aforementioned stacked structure come into contact with each other and are folded.

[0020] According to one embodiment, the aforementioned stacked structure can be alternately and repeatedly stacked on the first side and the second side to form a plurality of the aforementioned first curved regions and a plurality of the aforementioned second curved regions. The aforementioned negative electrode is formed in at least one of the plurality of the aforementioned first curved regions, and the aforementioned positive electrode of the aforementioned stacked structure is in contact with each other in the plurality of the aforementioned second curved regions.

[0021] According to one embodiment, the stacked structure formed by the positive electrode and the solid electrolyte, and the plurality of negative electrodes formed in the plurality of first bending regions, can be defined as a cellular structure. A plurality of cellular structures are formed, and the plurality of cellular structures are arranged in such a way that the positive electrodes included in the cellular structures are in contact with each other.

[0022] According to one embodiment, the above-mentioned stacked structure can be alternately and repeatedly stacked on the first side and the second side to form a plurality of the first bending regions and a plurality of the second bending regions, a plurality of the negative electrode is formed in the plurality of the first bending regions, and a plurality of gas diffusion layers are formed in the plurality of the second bending regions.

[0023] According to one embodiment, the aforementioned stacked structure, the plurality of negative electrodes formed in the plurality of ...

[0024] According to one embodiment, the secondary battery may include a positive electrode, a solid electrolyte, and a negative electrode, forming a stacked structure in which the positive electrode, the solid electrolyte, and the negative electrode are stacked sequentially. The stacked structure is bent toward a first side and a second side opposite to the first side. In the first bending region that bends toward the first side, the negative electrode contacts and folds with each other.

[0025] According to one embodiment, the secondary battery may further include a gas diffusion layer formed in a second bending region that bends toward the second side.

[0026] According to one embodiment, the positive electrode may contain compounds of copper, phosphorus and sulfur, oxygen is used as the positive electrode active material, the solid electrolyte contains bacterial cellulose, and the negative electrode contains zinc.

[0027] According to one embodiment, the above-mentioned positive electrode and the above-mentioned solid electrolyte can be in the form of a membrane morphology consisting of a network of multiple fibers.

[0028] The effects of the invention

[0029] The secondary battery of this application embodiment includes a positive electrode, a solid electrolyte, and a negative electrode. The positive electrode and the solid electrolyte can be in the form of a membrane with multiple fiber networks, and the negative electrode can have multiple grooves. Thus, the positive electrode, the solid electrolyte, and the negative electrode can have high flexibility and mechanical properties.

[0030] In the aforementioned secondary battery, the laminated structure formed by the positive electrode and the solid electrolyte can be bent. A bending region can be formed between the laminated structures, and the negative electrode can be formed within this bending region.

[0031] Therefore, the two sides of the negative electrode can be separated from the positive electrode by the solid electrolyte, thereby improving the charge-discharge characteristics and lifespan of the secondary battery. Attached Figure Description

[0032] Figure 1a and Figure 1b This is a diagram illustrating the curved structure of a secondary battery according to the first embodiment of this application.

[0033] Figure 2 This is a diagram illustrating the curved structure of a secondary battery according to the second embodiment of this application.

[0034] Figure 3 This is a diagram illustrating the bent structure of a secondary battery according to the third embodiment of this application.

[0035] Figure 4 This is a diagram illustrating the bent structure of a secondary battery according to the fourth embodiment of this application.

[0036] Figure 5a and Figure 5b This is a diagram illustrating the curved structure of a secondary battery according to the fifth embodiment of this application.

[0037] Figure 6 This is a diagram illustrating the curved structure of a secondary battery according to the sixth embodiment of this application.

[0038] Figure 7a and Figure 7b This is a diagram illustrating the curved structure of a secondary battery according to the seventh embodiment of this application.

[0039] Figure 8 This is a diagram illustrating the bent structure of a secondary battery according to the eighth embodiment of this application.

[0040] Figure 9a and Figure 9b This is a diagram illustrating the curved structure of a secondary battery according to the ninth embodiment of this application.

[0041] Figure 10 This is a diagram illustrating a secondary battery used to explain an embodiment of this application.

[0042] Figure 11 This is a diagram illustrating the negative electrode included in the curved structure secondary battery of this application and its preparation method.

[0043] Figure 12This diagram illustrates the solid electrolyte included in the bent structure secondary battery of this application and its preparation method.

[0044] Figure 13 This diagram illustrates the positive electrode included in the curved structure secondary battery of this application and its preparation method.

[0045] Figure 14 To take a scanning electron microscope (SEM) image of the negative electrode of Experimental Example 1-1 of this application.

[0046] Figure 15 This is a diagram illustrating the preparation process of the first composite fiber in Experimental Example 2-2 of this application.

[0047] Figure 16 This is a diagram illustrating the preparation process of the second composite fiber in Experimental Examples 2-3 of this application.

[0048] Figure 17 This is a diagram illustrating the preparation method of the solid electrolyte in the experimental examples of this application.

[0049] Figure 18 To capture an image of the positive electrode of Experimental Example 3 of this application.

[0050] Figure 19 A scanning electron microscope image of the cross-section of the secondary battery in Experimental Example 4 of this application.

[0051] Figure 20 The results are X-ray diffraction (XRD) measurements of the negative electrodes of Experimental Examples 1-1 and 1-2 of this application.

[0052] Figure 21 The graphs were used to measure the resistance changes caused by mechanical deformation of the negative electrode in Experimental Examples 1-1 and 1-2 of this application.

[0053] Figure 22 The results are X-ray photoelectron spectroscopy (XPS) analysis of the interface layer of the negative electrode after 100 charge-discharge cycles of a secondary battery including the negative electrode of Experimental Example 1-1 of this application.

[0054] Figure 23 The results of X-ray photoelectron spectroscopy analysis of the interface layer of the negative electrode of the secondary battery, including the negative electrode of Experimental Example 1-1 of this application, after 6000 charge-discharge cycles.

[0055] Figure 24 The results are X-ray diffraction analysis results of the solid electrolytes in Experimental Examples 2-4 to 2-8 of this application.

[0056] Figure 25The ionic conductivity of the solid electrolytes based on Experimental Examples 2-4 to 2-8 of this application was determined at temperature.

[0057] Figure 26 The ionic conductivity of the solid electrolyte and chitosan based on Experimental Examples 2-9 to 2-13 of this application was determined at temperature.

[0058] Figure 27 The temperature expansion rate of the solid electrolyte and chitosan based on Experimental Examples 2-9 to 2-13 of this application was determined.

[0059] Figure 28 The image shows the X-ray diffraction pattern of the positive electrode prepared according to Experimental Example 3 of this application.

[0060] Figure 29 This is a high-resolution transmission electron microscope (HRTEM) image of the positive electrode of Experimental Example 3, taken under the charge-discharge state of the secondary battery of Experimental Example 4 in this application.

[0061] Figure 30 The graphs are used to evaluate the redox reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) characteristics of the positive electrode based on the P and S composition ratio of Experimental Example 3 of this application.

[0062] Figure 31 The graphs are used to evaluate the OER, ORR, and HER characteristics of the crystal plane in the positive electrode of Experimental Example 3 of this application.

[0063] Figure 32 This is a graph illustrating the charge-discharge characteristics of the secondary battery in the bent state of Experimental Example 4 of this application.

[0064] Figure 33 This is a graph used to illustrate the changes in capacity and efficiency based on the number of charge-discharge cycles of the secondary battery in the bent state of Experimental Example 4 of this application.

[0065] Figure 34 A graph to evaluate the long-term stability of the secondary battery in the bending state of Experimental Example 4 of this application.

[0066] Figure 35 A graph showing the charge-discharge characteristics of the secondary battery in the bending state in Experimental Example 4 of this application, used for comparison with other batteries. Detailed Implementation

[0067] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the technical concept of the present invention is not limited to the embodiments described herein, and can be embodied in other forms. The embodiments described herein are merely intended to make the disclosure thorough and complete, and to fully convey the spirit of the present invention to those skilled in the art.

[0068] Furthermore, in the various embodiments of this specification, the terms "first," "second," "third," etc., are used only to describe various structural elements, which are not limited by these terms. These terms are only used to distinguish one structural element from others. Therefore, a first structural element mentioned in one embodiment may also be described as a second structural element in other embodiments. The embodiments described and illustrated herein also include complementary embodiments. Furthermore, the word "and / or" in this specification is used to mean including at least one of the structural elements listed above.

[0069] In this specification, unless otherwise explicitly stated in the context, singular expressions include plural expressions. Furthermore, terms such as "comprising" or "having" are used to indicate the presence of features, numbers, steps, structural elements, or combinations thereof described in the specification, and should not be construed as excluding the presence or additional possibilities of more than one other feature, number, structural element, or combination thereof. Also, in this specification, "connection" includes both indirect and direct connections among multiple structural elements.

[0070] Furthermore, in the following description of the present invention, detailed descriptions of relevant well-known functions or structures will be omitted if it is determined that such detailed descriptions would unnecessarily obscure the essence of the present invention.

[0071] Figure 1a and Figure 1b This is a diagram illustrating the curved structure of a secondary battery according to the first embodiment of this application.

[0072] Reference Figure 1a and Figure 1b The secondary battery with the curved structure in the first embodiment may include a positive electrode 300, a solid electrolyte 200, and a negative electrode 100.

[0073] The aforementioned positive electrode 300 and the aforementioned solid electrolyte 200 can be stacked to form a stacked structure.

[0074] The laminated structure, including the aforementioned positive electrode 300 and the aforementioned solid electrolyte 200, is bent, thereby forming a bent region between the laminated structures. For example... Figure 1a and Figure 1b As shown, the inner surface of the aforementioned curved region can be composed of the aforementioned solid electrolyte 200.

[0075] The negative electrode 100 can be formed within the curved region formed by the solid electrolyte 200. In other words, the negative electrode 100 is formed in a sandwich configuration in the stacked structure, and the negative electrode 100 can contact the solid electrolyte 200. That is, the negative electrode 100 can be separated from the positive electrode 300 by the solid electrolyte 200. Both the first surface and the second surface facing the first surface of the negative electrode 100 can be separated from the positive electrode 300 by the solid electrolyte 200.

[0076] The stacked structure formed by the positive electrode 300 and the solid electrolyte 200, and the negative electrode 100 formed in the bending region, can be defined as a unit cell.

[0077] like Figure 1a As shown, multiple unit cells can be formed, and these multiple unit cells can be stacked. The stacked unit cells can be defined as a cellular structure. In this case, multiple unit cells can be stacked in such a way that the positive electrode 300 included in adjacent unit cells are in contact with each other.

[0078] Therefore, the positive electrodes 300 included in the aforementioned different unit cells can be electrically connected to each other, and the negative electrodes 100 included in the aforementioned different unit cells can be separated from each other.

[0079] Leads can be formed on the open side of the plurality of mutually spaced negative electrodes 100, and the plurality of mutually spaced negative electrodes 100 can be electrically connected.

[0080] According to an embodiment of this application, as described above, the negative electrode 100 can be inserted into the curved region of the laminated structure including the positive electrode 300 and the solid electrolyte 200. Therefore, the solid electrolyte 200 can be formed between the first surface of the negative electrode 100 and the positive electrode 300, and between the second surface of the negative electrode 100 and the positive electrode 300. Thus, during the charging and discharging process of the secondary battery, ions (e.g., OH-) are released. - The electrode can move between the first surface of the negative electrode 100 and the positive electrode 300, and between the second surface of the negative electrode 100 and the positive electrode 300, thereby increasing the charge and discharge capacity of the secondary battery.

[0081] Figure 2 This is a diagram illustrating the curved structure of a secondary battery according to the second embodiment of this application.

[0082] Reference Figure 2 , refer to Figure 1a and Figure 1bThe first embodiment described herein forms multiple cellular structures.

[0083] Multiple of the aforementioned cellular structures can be arranged facing each other. Specifically, such as... Figure 2 As shown, multiple of the above-mentioned cellular structures can be configured such that the positive electrode 300 included in the above-mentioned cellular structures are in contact with each other.

[0084] Therefore, the positive electrode 300 included in the aforementioned different unit cells and the positive electrode 300 included in the aforementioned different cellular structures can be electrically connected without performing additional processes.

[0085] As described above, the different cellular structures can be configured to contact the positive electrode 300, thereby increasing the energy density of the secondary battery.

[0086] Figure 3 This is a diagram illustrating the bent structure of a secondary battery according to the third embodiment of this application.

[0087] Reference Figure 3 Provide a reference Figure 1a and Figure 1b The cellular structure of the first embodiment described herein allows for the formation of a gas diffusion layer 50 between the unit cells. Specifically, multiple unit cells can be stacked such that the positive electrode 300 included in adjacent unit cells are adjacent to each other, and the gas diffusion layer 50 can be formed between adjacent positive electrode 300.

[0088] like Figure 3 As shown, multiple unit cells can be formed, and multiple unit cells can be stacked. The stacked unit cells and the gas diffusion layer 50 between the unit cells can be defined as a cellular structure.

[0089] Through the gas diffusion layer 50, oxygen can be easily and smoothly supplied to the positive electrode 300 of the secondary battery with the curved structure of this application embodiment, which uses oxygen as the positive electrode active material, thereby improving the charge and discharge characteristics of the secondary battery.

[0090] Figure 4 This is a diagram illustrating the bent structure of a secondary battery according to the fourth embodiment of this application.

[0091] Reference Figure 4 , refer to Figure 3 The aforementioned cellular structure of the third embodiment described herein forms a plurality of such structures.

[0092] Multiple of the aforementioned cellular structures can be arranged facing each other. Specifically, such as... Figure 4 As shown, multiple of the above-mentioned cellular structures can be configured such that the positive electrode 300 included in the above-mentioned cellular structures are in contact with each other.

[0093] Therefore, the positive electrode 300 included in the aforementioned different unit cells and the positive electrode 300 included in the aforementioned different cellular structures can be electrically connected without performing additional processes.

[0094] As described above, the different cellular structures can be configured to contact the positive electrode 300, thereby increasing the energy density of the secondary battery.

[0095] Figure 5a and Figure 5b This is a diagram illustrating the curved structure of a secondary battery according to the fifth embodiment of this application.

[0096] Reference Figure 5a and Figure 5b The secondary battery with a curved structure in the fifth embodiment may include a positive electrode 300, a solid electrolyte 200 and a negative electrode 100, wherein the positive electrode 300 and the solid electrolyte 200 may be stacked to form a stacked structure.

[0097] The aforementioned stacked structure can be bent toward a first side and a second side opposite to the first side. This forms a first bending region 11 where the stacked structure bends toward the first side, and a second bending region 12 where the stacked structure bends toward the second side.

[0098] The negative electrode 100 can be formed within the first curved region 11. For example... Figure 5b As shown, the first curved region 11 can be opened toward the first side, and the negative electrode 100 can be formed in the opened first curved region 11.

[0099] In the second bending region 12, the positive electrodes 300 of the stacked structure can contact each other and be folded. In other words, no components are formed in the second bending region 12, but the positive electrodes 300 can be directly folded and brought into contact with each other.

[0100] The aforementioned stacked structure can be alternately and repeatedly bent toward the first side and the second side to form a plurality of the aforementioned first bending regions 11 and a plurality of the aforementioned second bending regions 12. At least one of the plurality of the aforementioned first bending regions 11 can form the aforementioned negative electrode 100, and in the plurality of the aforementioned second bending regions 12, the aforementioned positive electrode 300 of the aforementioned stacked structure can be in contact with each other.

[0101] The negative electrode 100 can be formed in the stacked structure in a sandwich configuration, and the positive electrode 300 and the solid electrolyte 200 included in the stacked structure can be formed continuously.

[0102] The aforementioned stacked structure formed by the aforementioned positive electrode 300 and the aforementioned solid electrolyte 200, and the aforementioned negative electrode 100 formed in the aforementioned first bending regions 11, can be defined as a cellular structure.

[0103] According to an embodiment of this application, the stacked structure formed by the positive electrode 300 and the solid electrolyte 200 can be bent toward the first side and the second side to insert the negative electrode 100 into the first bending region 11. Therefore, the secondary battery can be manufactured through a simple process of bending the stacked structure and inserting the negative electrode 100, and mass production is simplified through continuous processes.

[0104] Furthermore, as described later in Experimental Example 4, the Cu, P, and S compounds included in the positive electrode 300 can be coated onto a metal mesh, through which external air and / or oxygen can be easily supplied to the positive electrode 300. Thus, a secondary battery with a curved structure according to the fifth embodiment of this application can be realized without omitting a gas diffusion layer.

[0105] However, the gas diffusion layer can be omitted in the curved structure secondary battery of the fifth embodiment of this application, and the technical concept of the embodiments of this application does not exclude the inclusion of a gas diffusion layer.

[0106] Figure 6 This is a diagram illustrating the curved structure of a secondary battery according to the sixth embodiment of this application.

[0107] Reference Figure 6 , refer to Figure 5a and Figure 5b The cellular structure described in the fifth embodiment is formed in multiple ways.

[0108] Multiple of the aforementioned cellular structures can be arranged facing each other. Specifically, such as... Figure 6 As shown, multiple of the above-mentioned cellular structures can be configured such that the positive electrode 300 included in the above-mentioned cellular structures are in contact with each other.

[0109] Therefore, the positive electrode 300 included in the aforementioned different unit cells and the positive electrode 300 included in the aforementioned different cellular structures can be electrically connected without performing additional processes.

[0110] Figure 7a and Figure 7b This is a diagram illustrating the curved structure of a secondary battery according to the seventh embodiment of this application.

[0111] Reference Figure 7a and Figure 7b This can serve as a reference. Figure 5a and Figure 5bThe cellular structure of the fifth embodiment described herein can form a gas diffusion layer 50 within the second curved region 12. Specifically, compared with the reference... Figure 5a and Figure 5b The gas diffusion layer 50 can be formed in the second bending region 12 where the aforementioned layered structure bends toward the second side, as described above, thus, Figure 7a As shown, within the second curved region 12, the positive electrode 300 may not be in contact.

[0112] Through the gas diffusion layer 50, oxygen is easily and smoothly supplied to the positive electrode 300 of the secondary battery with the curved structure of this application embodiment, which uses oxygen as the positive electrode active material, thereby improving the charge and discharge characteristics of the secondary battery.

[0113] Figure 8 This is a diagram illustrating the bent structure of a secondary battery according to the eighth embodiment of this application.

[0114] Reference Figure 8 , refer to Figure 7a and Figure 7b The cellular structure described in the seventh embodiment is formed in multiple ways.

[0115] Multiple of the aforementioned cellular structures can be arranged facing each other. Specifically, such as... Figure 8 As shown, multiple of the above-mentioned cellular structures can be configured such that the positive electrode 300 included in the above-mentioned cellular structures are in contact with each other.

[0116] This can improve the energy density of the aforementioned secondary batteries.

[0117] Figure 9a and Figure 9b This is a diagram illustrating the curved structure of a secondary battery according to the ninth embodiment of this application.

[0118] Reference Figure 9a and Figure 9b The curved secondary battery of the ninth embodiment of this application may include a positive electrode 300, a solid electrolyte 200, and a negative electrode 100. The secondary battery may also include a gas diffusion layer 50.

[0119] The positive electrode 300, the solid electrolyte 200 and the negative electrode 100 can be stacked sequentially to form a stacked structure.

[0120] like Figure 5a and Figure 5b As shown, the aforementioned laminated structure can be bent toward a first side and a second side opposite to the first side. This forms a first bending region 11 where the laminated structure bends toward the first side, and a second bending region 12 where the laminated structure bends toward the second side.

[0121] In the first bending region 11, the negative electrode 100 of the stacked structure can be folded in a manner that brings them into contact with each other. In other words, no components are formed within the first bending region 11, but the negative electrode 100 can be directly folded and brought into contact with each other.

[0122] The gas diffusion layer 50 can be formed within the second curved region 12. For example... Figure 9b As shown, the second curved region 12 can be opened toward the second side, and the gas diffusion layer 50 can be formed within the opened second curved region 12.

[0123] The aforementioned stacked structure can be alternately and repeatedly bent toward the first side and the second side to form a plurality of the aforementioned first bending regions 11 and a plurality of the aforementioned second bending regions 12. In the plurality of the aforementioned first bending regions 11, the aforementioned negative electrode 100 of the aforementioned stacked structure can be in contact with each other, and in at least one of the plurality of the aforementioned second bending regions 12, the aforementioned gas diffusion layer 50 can be formed.

[0124] The positive electrode 300, the solid electrolyte 200 and the negative electrode 100 included in the above-mentioned stacked structure can be formed continuously. The stacked structure formed by stacking the positive electrode 300, the solid electrolyte 200 and the negative electrode 100, as well as the gas diffusion layer 50 formed in the plurality of the second bending regions 12, can be defined as a cellular structure.

[0125] According to an embodiment of this application, the stacked structure formed by the positive electrode 300, the solid electrolyte 200, and the negative electrode 100 can be bent toward the first side and the second side to insert the gas diffusion layer 50 into the second bending region 12. Therefore, the secondary battery can be prepared through a simple process of bending the stacked structure and inserting the gas diffusion layer 50, and mass production is simplified by a continuous roll-to-roll process.

[0126] Figure 10 This is a diagram illustrating a secondary battery used to explain an embodiment of this application.

[0127] Reference Figure 10 As shown in the first to ninth embodiments of this application above, the secondary battery of this application embodiment, including the positive electrode 300, the solid electrolyte 200, the negative electrode 100 and the current collector 400, may have a curved structure.

[0128] Therefore, the positive electrode 300, the solid electrolyte 200, and the negative electrode 100 can be formed using highly flexible materials and processes. Hereinafter, the negative electrode 100, the solid electrolyte 200, and the positive electrode 300 will be described sequentially.

[0129] Figure 11 This is a diagram illustrating the negative electrode included in the curved structure secondary battery of this application and its preparation method.

[0130] Reference Figure 11 A flat base metal substrate 10 is prepared. The base metal substrate 10 may include a first surface and a second surface facing the first surface, both of which may be flat. According to one embodiment, the base metal substrate 10 may contain zinc.

[0131] A plurality of beads 110 may be disposed on the aforementioned base metal substrate 10. After being mixed with a solvent, the plurality of beads 110 may be spin-coated onto the base metal substrate 10. The plurality of beads 110 may be disposed on the base metal substrate 10 with spacing between them. The plurality of beads 110 may be disposed on the aforementioned first surface of the base metal substrate 10. For example, the plurality of beads 110 may be polystyrene beads.

[0132] Before the plurality of beads 110 are disposed on the base metal substrate 10, the base metal substrate can be treated and cleaned with HCl. This removes the natural oxide film on the base metal substrate 10.

[0133] Furthermore, before the plurality of beads 110 are disposed on the base metal substrate 10, the first surface of the base metal substrate 10 can be hydrophilically treated. For example, the first surface of the base metal substrate 10 can be treated with a piranha solution to give the first surface of the base metal substrate 10 hydrophilic properties. As a result, the plurality of beads 110 can be stably and easily formed on the first surface of the base metal substrate 10.

[0134] The size of the plurality of beads 110 can be reduced. For example, oxygen plasma can be applied to the base metal substrate 10 having the plurality of beads 110 to remove the region adjacent to the surface of the plurality of beads 110, thereby reducing the size of the plurality of beads 110. While the size of the plurality of beads 110 can be reduced, the distance between the plurality of beads 110 can be increased.

[0135] A mask layer 120 may be formed on the base metal substrate 10 on which a plurality of beads 110 with reduced dimensions are arranged. The mask layer 120 may be formed of polymer using a spin coating process, thereby covering the base metal substrate 10 exposed between the plurality of beads 110. Furthermore, the mask layer 120 may not be formed on the bonding surface between the plurality of beads 110 and the base metal substrate 10.

[0136] Since the removal of multiple beads 110 may expose the etchable area 122 of the base metal substrate 10 that is not covered by the mask layer 120. As described above, the mask layer 120 may not be formed on the bonding surface between the multiple beads 110 and the base metal substrate 10. Therefore, after the removal of multiple beads 110, the etchable area 122 (the bonding surface) may be exposed regardless of whether the multiple beads 110 are in contact with the base metal substrate 10.

[0137] After the etched target area 122 is exposed, the mask layer 120 can be used as a mask to etch the exposed etched target area 122 of the base metal substrate 10 to prepare the negative electrode 100.

[0138] The mask layer 120 is used as a mask to etch the etch target area 122 to form a plurality of trenches 124 within the negative electrode 100. The plurality of trenches 124 may correspond to the etch target area 122. The plurality of trenches 124 may not penetrate the negative electrode 100. In other words, the plurality of trenches 124 may have a bottom surface and side surfaces and may have an open top surface.

[0139] The etched area 122 can be etched using an etching gas. According to one embodiment, the etching gas may include fluorine and sulfur. For example, the etching gas may include SF6.

[0140] According to one embodiment, a portion of the elements contained in the etching gas may remain on the bottom surface and / or the side surface of the plurality of trenches 124. This improves the characteristics of the negative electrode 100, which is described later, prepared from the base metal substrate 10. Specifically, during the charging and discharging process of the secondary battery containing the negative electrode 100, an interface layer may be formed on the surface (first surface) of the negative electrode 100 in contact with the dielectric. In this case, the formation of the interface layer can be guided by the elements contained in the etching gas remaining on the bottom surface and / or the side surface of the plurality of trenches 124, thereby allowing the interface layer to be formed stably and easily, improving the charging and discharging characteristics and lifespan of the secondary battery.

[0141] According to one embodiment, the diameter and depth of the plurality of grooves 124 can be controlled. Specifically, the diameter of the plurality of grooves 124 can be adjusted by controlling the diameter of the plurality of beads 110, and the diameter of the plurality of beads 110 can be controlled by adjusting the initial size of the plurality of beads 110 coated on the base metal substrate 10 or by reducing the size of the plurality of beads 110. The depth of the plurality of grooves 124 can be adjusted according to the process conditions (e.g., time, concentration, pressure, electricity, etc.) of the etching gas provided.

[0142] According to one embodiment, the crystal planes developed from the negative electrode 100 can be controlled according to the diameter and depth of the plurality of grooves 124. Specifically, as the depth of the plurality of grooves 124 increases from 100 nm to 500 nm, the (100) and (101) crystal planes become more developed, while the (002), (102), (103), and (110) crystal planes become less developed; as the depth decreases from 500 nm to 5 μm, the (100) and (101) crystal planes become less developed. Furthermore, as the diameter of the plurality of grooves 124 increases from 100 nm to 500 nm, the (100) and (101) crystal planes become more developed; as the diameter decreases from 500 nm to 1 μm, the (100) and (101) crystal planes become less developed.

[0143] Whether the crystal planes of the aforementioned negative electrode 100 are well-developed can be confirmed by X-ray diffraction analysis. As described above, when the diameter and depth of the plurality of grooves 124 increase from 100 nm to 500 nm, the ratio of the peak value corresponding to the (101) crystal plane to the peak value corresponding to the (002) crystal plane ((101) / (002)) can increase. When the diameter and depth of the plurality of grooves 124 are greater than 500 nm, the ratio of the peak value corresponding to the (002) crystal plane to the peak value corresponding to the (101) crystal plane ((101) / (002)) can decrease.

[0144] According to one embodiment, the electrochemical characteristics of the negative electrode 100 can be adjusted based on the ratio of the peak value corresponding to the (101) crystal plane to the peak value corresponding to the (002) crystal plane ((101) / (002)). Specifically, the higher the ratio of the peak value corresponding to the (101) crystal plane to the peak value corresponding to the (002) crystal plane ((101) / (002)), the lower the overpotential value of the secondary battery containing the negative electrode 100.

[0145] Therefore, the higher the ratio of the peak value corresponding to the (101) crystal plane to the peak value corresponding to the (002) crystal plane ((101) / (002)), the more controllable the diameter and depth of the plurality of grooves 124 can be, thereby improving the electrochemical characteristics of the negative electrode 100. For example, the diameter and depth of the plurality of grooves 124 can be 500 nm.

[0146] Furthermore, according to one embodiment, the lattice constant of the unit cell of the negative electrode 100 can be adjusted according to the diameter and depth of the plurality of grooves 124. Specifically, when the negative electrode 100 has a hexagonal crystal structure, as the diameter and depth of the plurality of grooves 124 increase, the a-axis lattice constant of the unit cell of the negative electrode 100 can increase, and the c-axis lattice constant can decrease.

[0147] The negative electrode 100 of the present application embodiment can be prepared by a method of sequentially forming a plurality of beads 110 and a mask layer 120 on the base metal substrate 10, removing the plurality of beads 110 and using the mask layer 120 as a mask to etch the base metal substrate 10.

[0148] Therefore, the negative electrode 100 having multiple grooves 124 can be prepared with high yield by a simple method, and the multiple grooves 124 have high flexibility and mechanical properties.

[0149] Figure 12 This diagram illustrates the solid electrolyte included in the bent structure secondary battery of this application and its preparation method.

[0150] Reference Figure 12 Chitosan derivatives are prepared. These chitosan derivatives can be in the form of a chitosan precursor mixed with a solvent. According to one embodiment, the chitosan derivatives can be in the form of chitosan chloride and a solvent with a solvent added. Accordingly, the chitosan chloride is readily soluble in the solvent, and the chitosan derivatives can be readily provided to the culture medium described later, thereby easily preparing cellulose conjugated with chitosan.

[0151] For example, the solvent may be aqueous acetic acid, and the solvent may contain at least one of glycidyltrimethylammonium chloride, (2-aminoethyl)trimethylammonium chloride, (2-chloroethyl)trimethylammonium chloride, (3-carboxypropyl)trimethylammonium chloride, or (formylmethyl)trimethylammonium chloride.

[0152] The chitosan described above exhibits excellent thermal and chemical stability, high ionic conductivity, and can retain OH ions for extended periods without loss. Furthermore, as described later, it demonstrates high interchangeability with zinc anodes and compounds of copper, phosphorus, and sulfur when used in metal-air batteries.

[0153] Chitosan bound to cellulose is generated from the aforementioned chitosan derivative. The step of generating the aforementioned cellulose bound to chitosan may include: preparing a culture medium containing the aforementioned chitosan derivative; and injecting a bacterial strain into the culture medium and culturing it to prepare a basic composite fiber 210 containing cellulose 212 bound to chitosan 214. In this case, the aforementioned cellulose 212 may be bacterial cellulose.

[0154] According to one embodiment, the cellulose 212 incorporating the chitosan 214 can be prepared by desalting the bacterial membrane after culturing it in the culture medium. The bacterial membrane can be prepared by culturing a culture medium containing the chitosan derivative along with yeast and raw materials for culturing bacteria (e.g., pineapple juice, peptone, disodium hydrogen phosphate, citric acid), and then inoculating the culture with a bacterial strain. For example, the bacterial strain can be *Acetobacter xylinum*.

[0155] After washing and drying the bacterial membranes cultured above, the above-mentioned basic composite fiber 210 containing the above-mentioned cellulose 212 bound with chitosan 214 can be prepared by desalting with an acidic solution (e.g., HCl), neutralizing, and removing the solvent. During the desalting process, residual Na, K, or cell covering material and debris can be removed to prepare high-purity cellulose 212 bound with chitosan 214.

[0156] Furthermore, the chitosan 214 can form a chemical bond with the cellulose 212. Accordingly, the cellulose 212 with chitosan 214 bonded to it can be observed to exhibit stretching vibrations corresponding to CN during X-ray photoelectron spectroscopy analysis.

[0157] According to one embodiment, the surface of the cellulose 212 with chitosan 214 bonded thereto can be oxidized by an oxidant, that is, the surface of the basic composite fiber 210 can be oxidized to prepare the first composite fiber 210a.

[0158] Specifically, the steps for preparing the first composite fiber 210a may include: adding the base composite fiber 210 to an aqueous solution containing an oxidant to prepare a source solution; adjusting the pH of the source solution to alkaline; adjusting the pH of the source solution to neutral; and washing and drying the slurry in the source solution to prepare the first composite fiber 210a.

[0159] For example, the aqueous solution containing the oxidant described above can be an aqueous solution of 2,2,6,6-tetramethylpiperidine-1-oxy. Alternatively, as another example, the aqueous solution containing the oxidant described above can contain 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy (4-Hydroxy-TEMPO), (Diacetoxyiodo)benzene, 4-amino-2,2,6,6-tetramethylpiperidine-1-oxy (4-Amino-TEMPO), 4-carboxy-2,2,6,6-tetramethylpiperidine-1-oxy (4-Carboxy-TEMPO), 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxy (4-Methoxy-TEMPO), or 2,2,6,6-tetramethylpiperidine-1-oxymethacrylate (TEMPO). It is at least one of the following: methacrylate, 4-acetamido-1-oxy, 3-carboxy-1-methylpyrrolidine-1-oxy, 4-maleimido-1-oxy, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxybenzoate, or 4-phosphonooxy-2,2,6,6-tetramethylpiperidine-1-oxy.

[0160] The aforementioned source solution may also contain a sacrificial agent and an additional oxidant for the oxidation reaction of the aforementioned basic composite fiber 210. The sacrificial agent may contain at least one of NaBr, sodium iodide, sodium bromate, sodium bromite, sodium borate, sodium chlorite, or sodium chloride. The additional oxidant may contain at least one of NaClO, potassium hypochlorite, lithium hypochlorite, sodium chlorite, perchloric acid, potassium perchlorate, lithium perchlorate, tetrabutylammonium perchlorate, zinc perchlorate, hydrogen peroxide, or sodium peroxide.

[0161] According to one embodiment, in the step of adjusting the pH of the source solution to alkaline, the pH of the source solution can be adjusted to 10. Accordingly, the oxidation reaction can be easily induced while minimizing precipitates, and the oxidation degree of the first composite fiber 110a can be increased compared to reaction conditions with a pH of 8-9.

[0162] According to one embodiment, the additional oxidant can be provided after the basic composite fiber 210 and the sacrificial agent are provided to the aqueous solution containing the oxidant. Furthermore, the additional oxidant can be provided dropwise. Accordingly, severe oxidation of the basic composite fiber 210 can be prevented, resulting in uniform and stable oxidation of the surface of the basic composite fiber 210.

[0163] Furthermore, according to one embodiment, a second composite fiber 110b can be prepared by replacing bromine with a nitrogen-containing first functional group 216 after bromine is bound to the surface of the cellulose 212 which is bonded with chitosan 214.

[0164] The first functional group 216 can be represented by the following chemical formula 1, and the first functional group 216 can be combined with the chitosan 214 and / or the cellulose 212.

[0165] Chemical Formula 1

[0166]

[0167] That is, the second composite fiber 210b mentioned above can have quaternary nitrogen.

[0168] Specifically, the steps for preparing the second composite fiber 210b may include: dispersing the basic composite fiber 210 in a first solvent and then adding a bromine source to prepare a first source solution; adding a coupling agent to the first source solution to prepare a reaction suspension; filtering, washing, and freeze-drying the reaction suspension to prepare a brominated basic composite fiber; dispersing the brominated basic composite fiber in a second solvent to prepare a second source solution; adding the first functional group 216 precursor to the second source solution to react; and filtering, washing, and freeze-drying the reaction solution to prepare the second composite fiber 210b.

[0169] For example, the first solvent and the second solvent described above may be the same, and may contain at least one of N,N-dimethylacetamide, acetamide, acetonitrile, ethanol, ethylenediamine, diethyl ether, or benzaldehyde.

[0170] For example, the bromine source mentioned above may include at least one of LiBr, sodium bromide, or potassium bromide.

[0171] For example, the coupling agent described above may contain N-bromosuccinimide and triphenylphosphine. This coupling agent allows bromine to easily bind to the surface of the basic composite fiber 210. Specifically, the bromine within the N-bromosuccinimide can bind to the basic composite fiber 210, and the triphenylphosphine can reduce the bromine precursor (bromine source or N-bromosuccinimide) to increase the reaction rate.

[0172] As described above, after obtaining the brominated basic composite fiber from the above reaction suspension, the brominated basic composite fiber can be freeze-dried. This minimizes the loss of bromine in the brominated basic composite fiber and minimizes the possibility of secondary reactions between bromine and other elements.

[0173] For example, the aforementioned precursor with the first functional group 216 may contain 1,4-diazabicyclo[2.2.2]octane.

[0174] Solid electrolytes can be prepared using the cellulose 212 incorporating the chitosan 214 described above.

[0175] As shown in Figure 5, the solid electrolyte described above can be prepared as a membrane composed of the basic composite fiber 210 containing the cellulose 212 incorporating the chitosan 214. Therefore, the solid electrolyte can provide multiple pores internally and has a high surface area, exhibiting excellent flexibility and mechanical properties.

[0176] The aforementioned solid electrolyte can exist in a mixture of crystalline and amorphous phases. More specifically, the proportion of the amorphous phase in the solid electrolyte can be higher than the proportion of the crystalline phase. Accordingly, the aforementioned solid electrolyte can possess high ion mobility.

[0177] According to one embodiment, the solid electrolyte can be prepared using a gelatin process involving the first composite fiber 210a and the second composite fiber 210b. In this case, the solid electrolyte may comprise the first composite fiber 210a and the second composite fiber 210b, which are cross-linked together. The first composite fiber 210a can increase the number of OH ions in the solid electrolyte and improve ionic conductivity, thereby increasing negative charge density and anti-swelling properties. Furthermore, the second composite fiber 210b can increase molecular weight to improve thermal stability, enhance ion exchange capacity to achieve high water solubility and high anti-swelling properties, improve cross-linking bonding with the first composite fiber 210a, and selectively exhibit high solubility in specific solvents (ion discerning selectivity). Accordingly, the charge / discharge characteristics and lifespan characteristics of the secondary battery containing the solid electrolyte can be improved.

[0178] Specifically, the steps for preparing the above-mentioned solid electrolyte may include: mixing the above-mentioned first composite fiber 210a and the above-mentioned second composite fiber 210b in a solvent to prepare a mixed solution; adding a crosslinking agent and an initiator to the above-mentioned mixed solution and reacting to prepare a suspension; pouring the above-mentioned suspension onto a substrate and drying it to prepare a composite fiber membrane; and performing an ion exchange process on the above-mentioned composite fiber membrane.

[0179] For example, the solvent may include a mixture of dichloromethane, 1,2-propanediol and acetone; the crosslinking agent may include glutaraldehyde; and the initiator may include N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide.

[0180] Furthermore, for example, the ion exchange process for the aforementioned composite fiber membrane may include the step of providing the composite fiber membrane with an aqueous solution of KOH and an aqueous solution of ZnTFSI. Therefore, the OH ion content within the aforementioned solid electrolyte can be increased.

[0181] As described above, according to the embodiments of this application, the solid electrolyte may include the membrane M, and the membrane M may include at least one of the basic composite fiber 210, the first composite fiber 210a, or the second composite fiber 210b.

[0182] Within the aforementioned solid electrolyte, the proportion of chitosan 214 can be easily controlled based on the content of the chitosan derivative supplied to the culture medium. The crystallinity, ionic conductivity, and expansion ratio of the solid electrolyte can be controlled based on the proportion of chitosan 214. Specifically, the higher the proportion of chitosan 214, the more gradually the crystallinity of the solid electrolyte can decrease.

[0183] According to one embodiment, the content of chitosan 214 can be greater than 30% by weight and less than 70% by weight. If the content of chitosan 214 is less than 30% by weight or more than 70% by weight, the ionic conductivity of the solid electrolyte can be significantly reduced, and the expansion ratio can be significantly increased.

[0184] However, according to the embodiments of this application, the proportion of chitosan 214 in the solid electrolyte can be greater than 30% by weight and less than 70% by weight. Therefore, the solid electrolyte can maintain high ionic conductivity while having a low expansion ratio.

[0185] Figure 13 This diagram illustrates the positive electrode included in the curved structure secondary battery of this application and its preparation method.

[0186] Reference Figure 13 It is possible to prepare a first precursor containing chalcogens, a second precursor containing phosphorus, and a third precursor containing transition metals.

[0187] According to one embodiment, the aforementioned chalcogenide element may contain sulfur. In this case, for example, the aforementioned first precursor may contain at least one of dithiooxazone, dithiobiuret, dithiouracil, acetylthiourea, thiourea, N-methylthiourea, bis(phenylthio)methane, 2-imino-4-thiobiuret, N,N'-dimethylthiourea, ammonium sulfide, methyl methanesulfonate, sulfur powder, sulfate, N,N-dimethylthioformamide, or Davy reagent methyl.

[0188] Alternatively, according to other embodiments, the chalcogenide element may include at least one of oxygen, selenium, or tellurium.

[0189] For example, the aforementioned second precursor may comprise at least one of tetradecylphosphonic acid, isocyclophosphamide, octadecylphosphonic acid, hexylphosphonic acid, trioctylphosphine, phosphoric acid, triphenylphosphine, ammonium phosphide, pyrophosphate, Davy reagent methyl, cyclophosphamide monohydrate, phosphorus trichloride, phosphorus oxychloride (V), thiophosphoric chloride, phosphorus pentachloride, or phosphorus pentasulfide.

[0190] According to one embodiment, the second precursor can be any different substances containing phosphorus. For example, a mixture of tetradecylphosphonic acid and isocyclophosphamide mixed in a 1:1 (M%) ratio can be used as the second precursor. Therefore, the stoichiometric ratio of the transition metal, phosphorus, and chalcogenide can be controlled to 1:1:1. As a result, as described later, the positive electrode 300 of the embodiments of this application can have a covellite structure, which can improve the electrochemical characteristics of the positive electrode 300.

[0191] According to one embodiment, the aforementioned transition metal may include copper. In this case, for example, the aforementioned third precursor may include at least one of copper chloride, copper(II) sulfate, copper(II) nitrate, copper selenide, copper oxychloride, copper acetate, copper carbonate, cuprous thiocyanate, copper sulfide, copper hydroxide, copper naphthenate, or copper(II) phosphate.

[0192] Alternatively, according to other embodiments, the aforementioned transition metal may include at least one of magnesium, manganese, cobalt, iron, nickel, titanium, zinc, aluminum, or tin.

[0193] A mixture can be prepared by mixing the first precursor, the second precursor, and the third precursor and adding a first reducing agent.

[0194] The first reducing agent can be added after the first precursor, the second precursor, and the third precursor are mixed in a solvent. For example, the solvent can be a mixture of ethanol and ethylenediamine. Alternatively, for example, the solvent can be a mixture of ethanol and toluene.

[0195] According to one embodiment, the orientation of the crystal facets of the electrode structure described below can be controlled according to the type and mixing ratio of the solvent. In other words, the development of the (101) crystal facets in the electrode structure can be controlled according to the type and mixing ratio of the solvent, thereby controlling the electrochemical characteristics of the electrode structure.

[0196] According to embodiments of this application, the (101) crystal plane can be developed in the electrode structure by selecting the above-mentioned solvent (e.g., a mixture of ethanol and ethylenediamine in a volume ratio of 1:3), thereby improving the electrochemical properties (e.g., redox reactions, oxygen evolution reactions, hydrogen evolution reactions) of the electrode structure.

[0197] After mixing the first precursor, the second precursor, and the third precursor in the above solvent, as follows: Figure 13 As shown in part (a), nucleation and crystallization can be performed.

[0198] For example, the first reducing agent mentioned above may include at least one of ammonium hydroxide, ammonium chloride, or tetramethylammonium hydroxide.

[0199] An intermediate product comprising multiple main components can be prepared by co-precipitating the mixture comprising the first precursor, the second precursor, the third precursor, the first reducing agent, and the solvent described above.

[0200] like Figure 13 As shown in section (b), the mixture described above can form an intermediate product after heat treatment. The intermediate product can have multiple backbones, which can form a network with each other.

[0201] For example, the mixture with the first reducing agent can be refluxed at 120°C and then washed with deionized water or ethanol.

[0202] During heat treatment, the first reducing agent, while functioning as a reducing agent, can maintain the pH and increase the reaction rate. Therefore, the aforementioned intermediate product having the multiple main components can be easily prepared. For example, when the transition metal is copper and the chalcogenide is sulfur, the intermediate structure can be CuPS with a copper-blue crystal structure.

[0203] Multiple fibrillated fibers containing the aforementioned transition metals, chalcogenides, and phosphorus can be prepared by adding a second reducing agent to the aforementioned intermediate product and subjecting it to pressure heat treatment, thereby branching out multiple branches from the aforementioned multiple main trunks.

[0204] According to one embodiment, a pressurized heat treatment process can be performed after adding the above-mentioned intermediate product and the above-mentioned second reducing agent to deionized water.

[0205] For example, the second reducing agent mentioned above may include at least one of Triton X-165, Triton X-102, Triton X-45, Triton X-114, Triton X-405, Triton X-101, pyromellitic acid, diamide, pernitrite, formaldehyde, thimerosal, or chloramine-T.

[0206] According to one embodiment, a chalcogenide supply source containing the aforementioned chalcogenide can also be added together with the second reducing agent. Thus, the chalcogenide lost during the reaction can be replenished by the chalcogenide supply source, thereby facilitating the formation of the aforementioned electrode structure, which is a sponge structure composed of a network of multiple fibrillated fibers.

[0207] For example, when the aforementioned sulfide element is sulfur, the source of the aforementioned sulfide element may include at least one of sodium bisulfite, sodium sulfate, sodium sulfide, sodium thiosulfate, sodium thiomethoxide, sodium ethanethiolate, or sodium methanethiolate.

[0208] The process of mixing the above intermediate product and the above second reducing agent in deionized water can be carried out under cooling conditions. This prevents the heat generated during the addition of the second reducing agent from causing an excessive increase in the reaction rate, thereby improving the electrochemical characteristics of the electrode 300 structure described later.

[0209] As described above, a second reducing agent is added to the aforementioned intermediate product and subjected to pressure heat treatment, such as... Figure 13 As shown in part (c), multiple branches can be branched from the above-mentioned multiple trunks, thereby forming the above-mentioned positive electrode 300 with a sponge structure consisting of a network of multiple fibrillated fibers.

[0210] The aforementioned positive electrode 300 with a sponge structure can be washed with deionized water and ethanol and then immersed in liquid nitrogen. This can improve the mechanical properties and flexibility of the aforementioned positive electrode 300 with a sponge structure.

[0211] Furthermore, after being immersed in liquid nitrogen, the aforementioned positive electrode 300 with a sponge structure is freeze-dried to remove residual solvent, thereby minimizing secondary reactions.

[0212] As described above, the positive electrode 300 may comprise a sponge-structure membrane consisting of a network of fibrillated fibers branching from the plurality of main trunks. Therefore, the positive electrode 300 may have a porous structure providing a plurality of pores with a size of 1 nm to 2 nm, and is flexible.

[0213] Furthermore, as described above, by controlling the type and proportion of the solvent mixed with the first, second, and third precursors, the (101) crystal plane can be developed in the electrode structure. Therefore, when performing X-ray diffraction analysis on the electrode structure, the peak value corresponding to the (101) crystal plane can have the highest value compared to the peak values ​​corresponding to other crystal planes. During X-ray diffraction measurements, the peak value corresponding to the (101) crystal plane can be observed in the range of 2θ values ​​from 19° to 21°.

[0214] The plurality of fibers constituting the positive electrode 300 may contain compounds of the transition metal, phosphorus, and chalcogenide. For example, when the transition metal is copper and the chalcogenide is oxygen, the fibers may be represented by the following chemical formula 2.

[0215] Chemical formula 2

[0216] CuP x S y

[0217] When the fiber constituting the positive electrode 300 is represented as shown in the above chemical formula 1, it can be x+y=1, 0.3≤x≤0.7, 0.3≤y≤0.7.

[0218] If x is less than 0.3 or greater than 0.7 and y is less than 0.3 or greater than 0.7 in the above chemical formula 1, the redox reaction, oxygen evolution reaction, and hydrogen evolution reaction characteristics of the above positive electrode 300 may be reduced. As a result, the above positive electrode 300 may not be able to react reversibly during the charging and discharging process of a metal-air battery containing the above electrode structure as the positive electrode.

[0219] However, according to embodiments of this application, the aforementioned positive electrode 300 is made of CuP x S y In the case of P, the composition ratio can be 0.3 or more and 0.7 or less, and the composition ratio of S can be 0.3 or more and 0.7 or less. This improves the redox reaction, oxygen evolution reaction, and hydrogen evolution reaction characteristics of the aforementioned positive electrode 300, and enhances the charge / discharge characteristics and lifespan of the metal-air battery containing the aforementioned electrode structure as the positive electrode.

[0220] When the metal-air battery, which includes the aforementioned positive electrode 300 as the positive electrode, is charged and discharged, the lattice spacing of the fibers included in the positive electrode 300 can be reversibly changed. Specifically, when the metal-air battery is charging, the lattice spacing can be 0.478 nm, and when the metal-air battery is discharging, the lattice spacing can be 0.466 nm. The lattice spacing of the fibers can be confirmed by high-resolution transmission electron microscopy.

[0221] According to an embodiment of this application, the positive electrode 300, which is a membrane morphology formed by a network of the plurality of fibrillated fibers, can be prepared by mixing the first precursor containing the chalcogenide element, the second precursor containing phosphorus, and the third precursor containing the transition metal, followed by co-precipitation and pressure heat treatment.

[0222] The above-mentioned positive electrode 300 with high electrochemical properties can be prepared by a low-cost method.

[0223] Furthermore, the aforementioned positive electrode 300 is prepared by co-precipitation and pressurized heat treatment, which can provide the above-mentioned electrode structure for the positive electrode of a metal-air battery that is easy to mass-produce and has a simple preparation process.

[0224] The following describes specific experimental examples of this application and their characteristic evaluation results.

[0225] Preparation of negative electrode in Experiment 1-1

[0226] Zinc foil was prepared as the base metal substrate. The zinc foil was ultrasonically treated with HCl for 5 minutes and then cleaned with deionized water and ethanol.

[0227] Prepare a piranha solution by mixing H2SO4, H2O and NH4OH in a ratio of 2.5:7:0.5 (v / v / v). Treat zinc foil with the piranha solution to improve its hydrophilicity. After washing with deionized water, dry the foil in a nitrogen and argon atmosphere.

[0228] Polystyrene beads were prepared and spin-coated onto zinc foil. Oxygen plasma was applied at a flow rate of 30 sccm and an RF temperature of 60 mTorr to etch the polystyrene beads and reduce their size.

[0229] Next, a photosensitive material containing chromium was coated onto a zinc foil containing polystyrene beads to prepare a mask layer, and the polystyrene beads were removed. Then, the mask layer was used as a mask and an etching gas containing argon and SF6 was provided under the conditions of 0.1 Pa, 40 sccm flow rate, and 60 W RF to form multiple trenches with a depth of 500 nm and a diameter of 500 nm on the zinc foil.

[0230] The negative electrode of Experiment 1-1 was prepared by removing the mask layer, ultrasonic treatment with diluted H2SO4, and drying in an argon atmosphere.

[0231] Figure 14 To take a scanning electron microscope image of the negative electrode of Experimental Example 1-1 of this application.

[0232] Reference Figure 14 Scanning electron microscope images of the negative electrode of Experiment 1-1 were taken, and it was confirmed that multiple grooves were formed in the zinc foil.

[0233] Preparation of the negative electrode in Experiment Example 1-2

[0234] Unpatterned zinc foil was prepared as the negative electrode for Experimental Examples 1-2.

[0235] Preparation of the basic composite fiber (CBC) in Experiment 2-1

[0236] Prepare *Acetobacter xylinum* as the bacterial strain and prepare chitosan derivatives. The chitosan derivatives were prepared as follows: 1 g of chitosan chloride was dissolved in a suspension of 1% (v / v) aqueous acetic acid for 24 hours under a N2 atmosphere at 65°C using 1M glycidyltrimethylammonium chloride. After precipitation, the solution was filtered multiple times with ethanol.

[0237] After preparing a Hestrin-Schramm (HS) medium containing pineapple juice (2%, w / v), yeast (0.5%, w / v), peptone (0.5%, w / v), disodium hydrogen phosphate (0.27%, w / v), citric acid (0.015%, w / v), and the aforementioned chitosan derivative (2%, w / v), the medium was steam-sterilized at 121°C for 20 minutes. Furthermore, after activating *Acetobacter xylinum* in pre-cultivation Hestrin-Schramm (HS) medium at 30°C for 24 hours, acetic acid was added to maintain the pH at 6.

[0238] Then, Acetobacter xylinum was cultured in Hestrin-Schramm (HS) medium at 30°C for 7 days.

[0239] The obtained bacterial pellicles were washed with deionized water, and the supernatant was neutralized. The supernatant was then dehydrated under vacuum at 105°C. Excess reagent was removed by demineralizing the generated cellulose with 1N HCl for 30 minutes (w / v, 1:15). The cellulose was then purified by repeated centrifugation with deionized water until the supernatant reached neutral pH. Finally, the basic composite fiber (chitosan-bacterial cellulose (CBC)) was prepared by evaporating all solvents at 100°C.

[0240] Preparation of the first composite fiber (oCBC) in Experiment 2-2

[0241] Figure 15 This is a diagram illustrating the preparation process of the first composite fiber in Experimental Example 2-2 of this application.

[0242] like Figure 15 As shown, the first composite fiber (2,2,6,6-tetramethylpiperidine-1-oxy-oxidized CBCs (oCBCs)) whose surface is oxidized is achieved by means of an oxidation reaction of 2,2,6,6-tetramethylpiperidine-1-oxy (TEMPO), sodium bromide (NaBr), and sodium hypochlorite (NaClO) to conjugate the hydroxymethyl and ortho-paradirecting acetamido basic composite fiber (CBC) with the oxide of 2,2,6,6-tetramethylpiperidine-1-oxy.

[0243] Specifically, 2 g of the basic composite fiber, dispersed in a 2 mM aqueous solution of 2,2,6,6-tetramethylpiperidine-1-oxy, was reacted with NaBr (1.9 mM). 5 mM NaClO was used as an additional oxidant.

[0244] After ultrasonic stirring of the reaction suspension, the reaction was carried out at room temperature for 3 hours. The pH of the suspension was maintained at 10 by continuously adding 0.5M NaOH solution. Then, 1N HCl was added to the suspension to maintain the pH neutral for 3 hours. The oxidized slurry formed in the suspension was washed three times with 0.5N HCl, and the supernatant was neutralized with deionized water.

[0245] Within 30 minutes, acetone and toluene are replaced with the washed slurry and dried to evaporate the solvent, ultimately yielding the first composite fiber (oCBC).

[0246] exist Figure 15As can be seen from this, the surface of the aforementioned basic composite fiber can be oxidized.

[0247] Preparation of the second composite fiber (qCBC) in Experiment 2-3

[0248] Figure 16 This is a diagram illustrating the preparation process of the second composite fiber in Experimental Examples 2-3 of this application.

[0249] like Figure 16 As shown, the basic composite fiber combined with the second composite fiber (covalently quaternized CBC, qCBC) having a nitrogen-containing first functional group is prepared by using a coupling agent of 1,4-diazabicyclo[2.2.2]octane to conjugate the brominated basic composite fiber (CBC) with the quaternary ammonium group.

[0250] Specifically, 1 g of the basic composite fiber, dispersed in N,N-dimethylacetamide (35 ml) solution, was reacted with a LiBr (1.25 g) suspension for 30 minutes. N-bromosuccinimide (2.1 g) and triphenylphosphine (3.2 g) were used as coupling agents. After stirring the two reaction mixtures for 10 minutes, the reaction was carried out at 80 °C for 60 minutes.

[0251] Next, after cooling the reaction suspension at room temperature, deionized water was added, filtered, rinsed with deionized water and ethanol, and freeze-dried to obtain brominated basic composite fibers (bCBC).

[0252] The brominated basic composite fiber was dissolved in 100 ml of N,N-dimethylacetamide and then reacted with 1.2 g of 1,4-diazabicyclo[2.2.2]octane.

[0253] The mixture was then treated with ultrasound for 30 minutes and reacted at room temperature for 24 hours. The resulting solution was mixed with diethyl ether, washed five times with diethyl ether / ethyl acetate, and then freeze-dried to obtain the second composite fiber (covalently quaternized basic composite fiber (qCBC)).

[0254] exist Figure 16 It can be confirmed that the surface of the above-mentioned basic composite fiber is bonded with a first functional group having nitrogen.

[0255] Preparation of solid electrolytes (CBCs) in Experiments 2-4 to 2-8

[0256] Figure 17 This is a diagram illustrating the preparation method of the solid electrolyte in the experimental examples of this application.

[0257] like Figure 17As shown, the solid electrolyte is prepared using a gelatin process with the first composite fiber (oCBC) and the second composite fiber (qCBC) described above. Specifically, the first composite fiber (oCBC) and the second composite fiber (qCBC) are dissolved in a mixture of dichloromethane, 1,2-propanediol, and acetone (8:1:1, v / v / v%) using ultrasound in the same weight ratio. Then, 1% by weight of glutaraldehyde as a crosslinking agent and 0.3% by weight of N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide as an initiator are added.

[0258] After removing air bubbles from the gel suspension using a vacuum chamber (200 Pa), it was poured onto a glass surface at 60°C for 6 hours. The composite fiber membrane was then coagulated and peeled off using deionized water, rinsed with deionized water, and then vacuum dried.

[0259] Solid electrolytes (CBCs) were prepared by ion exchange with 1M KOH aqueous solution and 0.1M ZnTFSI for 6 hours at room temperature. Then, to avoid reaction with CO2 and formation of carbonates, a washing and impregnation process was performed with deionized water under N2 atmosphere.

[0260] exist Figure 17 It can be confirmed that the first composite fiber (oCBC) and the second composite fiber (qCBC) are cross-linked and combined to form the solid electrolyte (CBCs).

[0261] Furthermore, referring to Figure 10 OH ions can hop (grotthuss transport) on the surfaces of the first composite fiber (oCBC) and the second composite fiber (qCBC) crosslinked with the aforementioned solid electrolyte (CBCs), and can also move through diffusion within the interior separated from the surfaces of the first and second composite fibers. Furthermore, as referenced... Figure 12 As will be described later, the aforementioned solid electrolytes (CBCs) can have an amorphous phase, which can have higher ionic conductivity compared to crystalline structures.

[0262] In the preparation process of the above-mentioned solid electrolytes (CBCs), the ratio of the first composite fiber (oCBC) and the second composite fiber (qCBC) is adjusted as shown in Table 1 below.

[0263] Table 1

[0264] distinguish First composite fiber Second composite fiber Experimental Example 2-4 10wt% 90wt% Experimental Example 2-5 30wt% 70wt% Experimental Example 2-6 50wt% 50wt% Experimental Example 2-7 70wt% 30wt% Experimental Example 2-8 90wt% 10wt%

[0265] Preparation of solid electrolytes in Experiments 2-9 to 2-13

[0266] Based on Experiment 2-1 above, basic composite fibers were prepared, and the proportion of chitosan derivatives added was adjusted to prepare basic composite fibers with different chitosan contents. Then, based on Experiment 2-6 above, using basic composite fibers with different chitosan contents, as shown in Table 2, solid electrolytes of Experiments 2-9 to 2-13 were prepared.

[0267] Table 2

[0268] distinguish Chitosan ratio Experimental Example 2-9 10wt% Experimental Example 2-10 30wt% Experimental Example 2-11 50wt% Experimental Example 2-12 70wt% Experimental Example 2-13 90wt%

[0269] Preparation of the positive electrode and secondary battery in Experiment Example 3

[0270] Dithiocarbamate was prepared as a first precursor containing sulfur, a mixture of tetradecylphosphonic acid and isocyclophosphamide (1:1, M%) was prepared as a second precursor containing phosphorus, copper chloride was prepared as a third precursor containing copper, and a mixture of ethanol and ethylenediamine (1:3 v / v%) was prepared as a solvent.

[0271] After adding the first to third precursors to the solvent, a suspension is prepared by stirring.

[0272] Then, 2.5M% ammonium hydroxide was added as the first reducing agent, and after stirring for 2 hours, the mixture was heat-treated at 120°C for 6 hours to obtain the intermediate product. After washing with deionized water and ethanol, the product was dried in a vacuum at 50°C.

[0273] In an ice-water bath, the intermediate product was mixed and stirred in 20 ml of deionized water containing Triton X-165 as a second reducing agent and sodium bisulfite as a sulfur source. Then, the mixture was subjected to pressure heat treatment at 120°C for 24 hours to prepare a membrane formed by a compound of copper, phosphorus, and sulfur and consisting of a network of multiple fibrillated fibers.

[0274] The CuPS electrode structure of Experimental Example 3 with well-developed (101) crystal planes was prepared by washing the membrane with deionized water and ethanol to adjust it to neutral pH, storing it at -70°C for 2 hours, immersing it in liquid nitrogen, and freeze-drying it under vacuum.

[0275] In the preparation of the electrode structure in Experimental Example 3, the ratio of the first precursor containing sulfur and the second precursor containing phosphorus was adjusted, and the ratio of P and S in CuPS was adjusted to 0.1:0.9, 0.2:0.8, 0.3:0.7, 0.5:0.5, 0.7:0.3 and 0.9:0.1, respectively.

[0276] Figure 18 To capture an image of the positive electrode of Experimental Example 3 of this application.

[0277] Reference Figure 18The positive electrode (CuP) prepared according to Experimental Example 3 above was photographed. 0.5 S 0.5 It can be confirmed that the positive electrode of Experimental Example 3 is approximately 10 cm long and flexible.

[0278] Preparation of secondary batteries in Experiment Example 4

[0279] The pouch cell (zinc-air battery) of Example 4 was prepared using a negative electrode with multiple grooves having a depth of 500 nm and a diameter of 500 nm according to Example 1-1, a solid electrolyte according to Example 2-6, and a CuPS positive electrode with a P:S ratio of 0.5:0.5 according to Example 3.

[0280] Specifically, a slurry was prepared by mixing the positive electrode (90 wt%), super P-carbon (5 wt%), and polytetrafluoroethylene (PTFE) (5 wt%) from Example 3 in an N-methyl-pyrrolidone solution containing 0.5 wt% perfluorosulfonate resin (Nafion). The slurry was coated onto a stainless steel mesh and the solvent was evaporated. It was then cut into 6 cm × 1.5 cm pieces and dried under vacuum.

[0281] Afterwards, the positive electrode prepared and cut by the above method and the solid electrolyte of Experiment 2-6 were stacked and bent, and the negative electrode of Experiment 1-1 was placed in the bent area, and the secondary battery (zinc-air battery) of Experiment 4 was prepared by applying pressure.

[0282] Figure 19 A scanning electron microscope image of the cross-section of the secondary battery in Experimental Example 4 of this application.

[0283] Reference Figure 19 According to Experimental Example 4 of this application, a cross-section of a secondary battery having the negative electrode of Experimental Example 1-1, the solid electrolyte of Experimental Example 2-6, and the CuPS positive electrode of Experimental Example 3 was photographed.

[0284] like Figure 19 As shown, it can be confirmed that the negative electrode is formed in a sandwich configuration on the solid electrolyte and the positive electrode, and the interface between the negative electrode and the solid electrolyte and the interface between the solid electrolyte and the positive electrode can be confirmed.

[0285] Figure 20 The results are X-ray diffraction measurements of the negative electrodes of Experimental Examples 1-1 and 1-2 of this application.

[0286] Reference Figure 20 X-ray diffraction measurements were performed on the negative electrodes of Experimental Example 1-1 and Experimental Example 1-2.

[0287] like Figure 20 As shown, when the patterning process was not performed according to Experimental Example 1-2, it can be confirmed that the peak value corresponding to the (002) crystal plane is greater than the peak value corresponding to the (100) crystal plane. Conversely, when the patterning process was performed according to Experimental Example 1-1, it can be confirmed that the peak value corresponding to the (002) crystal plane is reduced, and thus the peak value corresponding to the (002) crystal plane is less than the peak value corresponding to the (100) crystal plane.

[0288] In other words, the fact that the peak value corresponding to the (002) crystal plane is less than the peak value corresponding to the (100) crystal plane can be a material characteristic caused by the preparation method of the negative electrode in the embodiments of this application.

[0289] Figure 21 The graphs were used to measure the resistance changes caused by mechanical deformation of the negative electrode in Experimental Examples 1-1 and 1-2 of this application.

[0290] Reference Figure 21 Pressure was applied to the negative electrode of Experiment 1-1 and Experiment 1-2 and 20,000 bends were performed. The resistance change after each bend was measured.

[0291] like Figure 21 As shown, it can be confirmed that the resistance of the negative electrode in Experimental Example 1-2, which did not undergo a patterning process, increased sharply after 5600 bending cycles. Conversely, it can be confirmed that the resistance of the negative electrode in Experimental Example 1-1, which had a patterning process and thus had multiple grooves, remained substantially unchanged after more than 20000 bending cycles.

[0292] As a result, it can be confirmed that the negative electrode of Experiment 1-1 has excellent mechanical properties and flexibility.

[0293] Figure 22 The results of X-ray photoelectron spectroscopy analysis of the interface layer of the negative electrode after 100 charge-discharge cycles of the secondary battery including the negative electrode of Experimental Example 1-1 of this application are as follows: Figure 23 The results of X-ray photoelectron spectroscopy analysis of the interface layer of the negative electrode of the secondary battery, including the negative electrode of Experimental Example 1-1 of this application, after 6000 charge-discharge cycles.

[0294] Reference Figure 22 and Figure 23 After performing 100 and 6000 charge-discharge cycles on the secondary battery of Experimental Example 4, which included the negative electrode of Experimental Example 1-1, X-ray photoelectron spectroscopy analysis was performed on the interface layer formed on the surface of the negative electrode.

[0295] like Figure 22 and Figure 23As shown, the interface layer formed on the surface of the negative electrode may contain Zn, C, S and F, and the Zn-O, C=O and CO vibrations can be confirmed.

[0296] The bonding of Zn-F and Zn-S in the interface layer is less than 5 at%, but it performs the important function of stabilizing the zinc electrode surface. In addition to the bonding of Zn-F and Zn-S, it can be confirmed that the elastic characteristics of the solid electrolyte of this application embodiment with bacterial cellulose stabilize the interface layer on the surface of the negative electrode.

[0297] Furthermore, as charge-discharge cycles were performed, an increase in the ratio of Zn-F to Zn-S (ZnF / ZnS) was confirmed, reaching approximately 8.6 at% after 6000 charge-discharge cycles. This can be attributed to the physical and electrochemical characteristics resulting from the combination of the solid electrolyte and negative electrode in the embodiments of this application.

[0298] Figure 24 The results are X-ray diffraction analysis results of the solid electrolytes in Experimental Examples 2-4 to 2-8 of this application.

[0299] Reference Figure 24 X-ray diffraction analysis was performed on the solid electrolytes of Experimental Examples 2-4 to 2-8 above.

[0300] exist Figure 24 As can be seen from the results, the solid electrolytes of Experimental Examples 2-4 to 2-8 have peak values ​​corresponding to the (101) and (002) crystal planes. The crystal structure does not change substantially with the ratio of the first composite fiber (oCBC) and the second composite fiber (qCBC). However, with the increase of the ratio of the second composite fiber, the 2θ value of the peak value corresponding to the (002) crystal plane increases slightly.

[0301] Figure 25 The results were obtained to measure the ion transport rate of the solid electrolytes in Experimental Examples 2-4 to 2-8 of this application based on temperature.

[0302] Reference Figure 25 The ionic conductivity of the solid electrolytes in Experiments 2-4 to 2-8 was measured at temperature, and the ionic conductivity of commercially available A201 membranes was measured at temperature for comparison.

[0303] exist Figure 25 As can be seen, the ionic conductivity of the solid electrolyte and the A201 membrane in Experiments 2-4 to 2-8 increases with increasing temperature. Furthermore, it can be confirmed that the ionic conductivity of the solid electrolyte in Experiments 2-4 to 2-8 is significantly higher than that of the A201 membrane.

[0304] Based on this, it can be confirmed that the solid electrolyte prepared according to Example 2-6 with the same ratio of first composite fiber to second composite fiber has a significantly higher ionic conductivity than the solid electrolytes of Example 2-4, Example 2-5, Example 2-7, and Example 2-8. As a result, it can be confirmed that controlling the proportion of the first composite fiber to be greater than 30% by weight and less than 70% by weight, and controlling the proportion of the second composite fiber to be less than 70% by weight and greater than 30% by weight, is an effective method to improve the ionic conductivity of OH ions.

[0305] Figure 26 The ionic conductivity of the solid electrolyte and chitosan based on Experimental Examples 2-9 to 2-13 of this application was determined at temperature.

[0306] Reference Figure 26 For the solid electrolytes and chitosan in Experiments 2-9 to 2-13, the ionic conductivity was determined based on temperature.

[0307] like Figure 26 As shown, the ionic conductivity of the solid electrolytes and chitosan in Experiments 2-9 to 2-13 increases with increasing temperature. Furthermore, it can be confirmed that the ionic conductivity of the solid electrolytes in Experiments 2-9 to 2-13 is significantly improved compared to chitosan.

[0308] Furthermore, according to Experiment 2-11, it can be confirmed that the ionic conductivity of the solid electrolyte with 50 wt% chitosan is significantly improved compared to the solid electrolytes of Experiments 2-9, 2-10, 2-12, and 2-13. As a result, it can be confirmed that controlling the proportion of chitosan in the solid electrolyte within a range greater than 30 wt% and less than 70 wt% is an effective method for improving the ionic conductivity of OH ions.

[0309] Figure 27 The temperature expansion rate of the solid electrolyte and chitosan based on Experimental Examples 2-9 to 2-13 of this application was determined.

[0310] Reference Figure 27 For the solid electrolytes and chitosan in Experiments 2-9 to 2-13 above, the expansion rate was determined based on temperature.

[0311] like Figure 27As shown, the expansion rate of the solid electrolyte and chitosan in Examples 2-9 to 2-13 increases with increasing temperature. Furthermore, based on Example 2-11, it can be confirmed that the expansion rate of the solid electrolyte containing 50 wt% chitosan is significantly lower than that of the solid electrolytes in Examples 2-9, 2-10, 2-12, and 2-13. Therefore, it can be confirmed that controlling the proportion of chitosan in the solid electrolyte within a range greater than 30 wt% and less than 70 wt% is an effective method for reducing the expansion rate.

[0312] Figure 28 The image shows the X-ray diffraction pattern of the positive electrode prepared according to Experimental Example 3 of this application.

[0313] Reference Figure 28 X-ray diffraction was performed on the positive electrode prepared according to Example 3.

[0314] like Figure 28 As shown, it can be confirmed that the positive electrode of Experimental Example 3 has a (101) crystal plane, a (111) crystal plane, a (210) crystal plane, a (120) crystal plane, a (220) crystal plane, a (022) crystal plane, a (103) crystal plane, and a (222) crystal plane. In particular, the peak value corresponding to the (101) crystal plane is significantly higher than the peak values ​​corresponding to the other crystal planes. Furthermore, it can be seen that the positive electrode of Experimental Example 3 is an orthorhombic crystal with a space group of Pnm21 and has a covellite appearance.

[0315] Figure 29 This is a high-resolution transmission electron microscope (HRTEM) image of the positive electrode of Experimental Example 3, taken under the charge-discharge state of the secondary battery of Experimental Example 4 in this application.

[0316] Reference Figure 29 High-resolution transmission electron microscopy (TEM) images of the electrode structure from Experiment 3 were taken under the charging and discharging conditions of the secondary battery in Experiment 4. CuP was used. 0.1 S 0.9 CuP 0.5 S 0.5 and CuP 0.9 S 0.1 The electrode structure used in Experiment Example 3. Figure 29 Parts a, b, and c are CuP 0.1 S 0.9 High-resolution transmission electron microscope image, Figure 29 The d, e, and f parts are CuP 0.5 S 0.5 High-resolution transmission electron microscope image, Figure 29 The g, h, and i parts are CuP 0.9S 0.1 High-resolution transmission electron microscopy image.

[0317] As mentioned above, in CuP 0.1 S 0.9 and CuP 0.9 S 0.1 In such cases, because the redox bond of Cu is located at a higher position than the S 3p bond, the oxidized sulfur may become unstable. Therefore, as... Figure 29 As shown, it can be confirmed that even with charging and discharging, the lattice spacing cannot be reversibly restored. Conversely, in CuP... 0.5 S 0.5 Under these conditions, it can be confirmed that the lattice spacing is 0.466nm before charging, 0.478nm after charging, and 0.466nm after discharging. The lattice spacing is reversibly restored after charging and discharging.

[0318] Figure 30 The graphs are used to evaluate the redox reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) characteristics of the positive electrode based on the P and S composition ratio of Experimental Example 3 of this application.

[0319] Reference Figure 30 In the CuPS electrode structure of Experimental Example 3, the characteristics of the redox reaction, oxygen evolution reaction and hydrogen evolution reaction based on the composition ratio of P and S were measured and shown.

[0320] from Figure 30 It can be seen that in the CuPS electrode structure, when the P composition ratio is greater than 0.3 and less than 0.7, and the S composition ratio is less than 0.7 and greater than 0.3, the oxygen evolution reaction and hydrogen evolution reaction characteristics of the redox reaction are excellent. In other words, it can be confirmed that controlling the P composition ratio to be greater than 0.3 and less than 0.7, and the S composition ratio to be less than 0.7 and greater than 0.3 in the CuPS electrode structure is an effective method to improve the oxygen evolution reaction and hydrogen evolution reaction characteristics of the redox reaction.

[0321] Figure 31 The graphs are used to evaluate the OER, ORR, and HER characteristics of the crystal plane in the positive electrode of Experimental Example 3 of this application.

[0322] Reference Figure 31 Based on the crystal planes of the CuPS electrode structure in Experimental Example 3, the overpotentials related to the oxygen evolution reaction and redox reaction (bifunctional activity) and the overpotential related to the hydrogen evolution reaction were calculated using discrete Fourier transform.

[0323] from Figure 31It can be confirmed that the overpotential value of the (101) crystal plane is the lowest. Therefore, it can be confirmed that the redox reaction, oxygen evolution reaction, and hydrogen evolution reaction characteristics of the electrode structure with well-developed (101) crystal plane are improved according to the embodiments of this application.

[0324] In summary, it can be seen that preparing the above-mentioned electrode structure with well-developed (101) crystal planes and using it as the positive electrode of a metal-air battery is an effective method to improve the charge-discharge characteristics of a metal-air battery.

[0325] Figure 32 This is a graph illustrating the charge-discharge characteristics of the secondary battery in the bent state of Experimental Example 4 of this application.

[0326] Reference Figure 32 For the secondary battery in Experiment Example 4, it was bent sequentially at 0°, 90°, 180° and 0° and then subjected to a 25mAcm test. -2 Under certain conditions, charging and discharging are performed.

[0327] like Figure 32 As shown, it can be confirmed that the secondary battery in Experimental Example 4, even when bent at multiple angles, does not have a substantial impact on its charging and discharging characteristics. That is, it can be confirmed that a flexible secondary battery can be embodied using the negative electrode, solid electrolyte, and positive electrode of the embodiments of this application.

[0328] Figure 33 This is a graph used to illustrate the changes in capacity and efficiency based on the number of charge-discharge cycles of the secondary battery in the bent state of Experimental Example 4 of this application.

[0329] Reference Figure 33 The secondary battery prepared according to Experimental Example 4 was bent 180° and tested at 25 mA / cm. -2 Under certain conditions, charging and discharging are performed.

[0330] like Figure 33 As shown, it can be confirmed that even when performing charge and discharge cycles under a 180° bending condition, the charge and discharge capacity and coulombic efficiency are driven stably without substantial decrease.

[0331] Figure 34 A graph to evaluate the long-term stability of the secondary battery in the bending state of Experimental Example 4 of this application.

[0332] Reference Figure 34 The secondary battery in Experiment Example 4 was bent 180° and subjected to a 25 mA / cm test. -2 Under certain conditions, it will undergo 6000 charge-discharge cycles over 8 hours.

[0333] like Figure 34As shown, it can be confirmed that the secondary battery in Experimental Example 4 operates stably in a bent state, and even with an increase in the number of charge and discharge cycles, there is no substantial decrease in characteristics in the bent state.

[0334] Figure 35 A graph showing the charge-discharge characteristics of the secondary battery in the bending state in Experimental Example 4 of this application, used for comparison with other batteries.

[0335] Reference Figure 35 In Experiment 4, a secondary battery (Pt / C+RuO2) was prepared by replacing the positive electrode with Pt / C and RuO2. A commercial zinc-air battery was prepared using PVA dielectric, zinc foil, and Pt / C and RuO2. In Experiment 4, the charge-discharge characteristics were compared with other secondary batteries in a bent state.

[0336] like Figure 35 As shown, in the case of commercial zinc-air batteries, the characteristics deteriorate sharply when bent, making it impossible to perform charge and discharge operations. In the case of zinc-air batteries containing Pt / C and RuO2 positive electrodes, the charge and discharge characteristics deteriorate sharply with increasing bending angle.

[0337] Conversely, it can be confirmed that the secondary battery in Experimental Example 4 of this application operates stably without changes in charge-discharge characteristics at multiple bending angles.

[0338] The present invention has been described in detail above using preferred embodiments, but the scope of the invention is not limited to the specific embodiments, but should be interpreted through the appended claims. Furthermore, it should be understood that those skilled in the art can make various modifications and variations without departing from the scope of the invention.

[0339] Industrial applicability

[0340] The curved secondary battery of this application embodiment can be applied to various industrial fields such as portable mobile devices, energy storage devices, and electric vehicle batteries.

Claims

1. A secondary battery, characterized in that, Includes positive electrode, solid electrolyte and negative electrode. This forms a laminated structure consisting of the aforementioned positive electrode and the aforementioned solid electrolyte. The aforementioned stacked structure bends toward a first side and a second side opposite to the first side to form a first bending region and a second bending region. The negative electrode is formed in the first bending region. The aforementioned negative electrode has multiple grooves formed. The aforementioned positive electrode comprises a compound of copper, phosphorus, and sulfur. The aforementioned stacked structure formed by the aforementioned positive electrode and the aforementioned solid electrolyte, and the aforementioned negative electrode formed in the aforementioned first bending region, are defined as a unit cell. The above-mentioned unit cells are formed in multiple ways. Multiple unit cells are stacked on top of each other, such that the positive electrodes included in adjacent unit cells are in contact. The stacked unit cells are defined as a first cellular structure. The aforementioned first cellular structure is formed in multiple forms. The plurality of the aforementioned first cellular structures are arranged in such a manner that the positive electrode included in the aforementioned first cellular structures is in contact with each other. Within the aforementioned first curved region, the negative electrode is formed in a sandwich configuration between the solid electrolytes, directly contacting the upper and lower portions of the solid electrolytes. The aforementioned solid electrolytes include chitosan bound to bacterial cellulose. The content of chitosan in the solid electrolyte is greater than 30% by weight and less than 70% by weight.

2. The secondary battery according to claim 1, characterized in that, It also includes a gas diffusion layer disposed between the stacked unit cells.

3. The secondary battery according to claim 2, characterized in that, The stacked unit cells and the gas diffusion layer disposed between the unit cells are defined as a second cellular structure. The second cellular structure is configured to allow the positive electrodes to contact each other.

4. The secondary battery according to claim 1, characterized in that, In the second bending region that bends toward the second side, the positive electrodes of the stacked structure come into contact with each other and fold.

5. The secondary battery according to claim 4, characterized in that, The aforementioned layered structure is alternately and repeatedly layered towards the first side and the second side to form multiple first curved regions and multiple second curved regions. The negative electrode is formed in at least one of the aforementioned first bending regions. In the multiple second curved regions, the positive electrodes of the stacked structures are in contact with each other.

6. The secondary battery according to claim 5, characterized in that, The aforementioned stacked structure formed by the positive electrode and the solid electrolyte, and the plurality of negative electrodes formed in the plurality of the aforementioned first bending regions, are defined as a third cellular structure. The aforementioned third cellular structure forms multiple structures. Multiple third cell structures are arranged in such a way that the positive electrodes included in the third cell structures are in contact with each other.

7. The secondary battery according to claim 4, characterized in that, The aforementioned layered structure is alternately and repeatedly layered towards the first side and the second side to form multiple first curved regions and multiple second curved regions. Multiple negative electrodes are formed in the aforementioned first bending regions, respectively. Multiple gas diffusion layers are formed in multiple of the aforementioned second bending regions.

8. The secondary battery according to claim 7, characterized in that, The aforementioned stacked structure, the plurality of negative electrodes formed in the plurality of ... The aforementioned fourth cellular structure forms multiple structures. Multiple fourth cell structures are arranged in such a way that the positive electrodes included in the fourth cell structures are in contact with each other.

9. A secondary battery, characterized in that, Includes positive electrode, solid electrolyte and negative electrode. The aforementioned negative electrode has multiple grooves formed. The aforementioned positive electrode contains compounds of copper, phosphorus, and sulfur. A stacked structure is formed by sequentially stacking the above-mentioned positive electrode, the above-mentioned solid electrolyte, and the above-mentioned negative electrode. The aforementioned layered structure bends toward a first side and a second side opposite to the first side to form multiple first bending regions and second bending regions. In the aforementioned plurality of first bending regions that bend towards the first side, the aforementioned negative electrodes are in contact with each other and folded. Within the aforementioned first curved region, the negative electrode is formed in a sandwich configuration between the solid electrolytes, directly contacting the upper and lower portions of the solid electrolytes. The aforementioned solid electrolytes include chitosan bound to bacterial cellulose. The content of chitosan in the solid electrolyte is greater than 30% by weight and less than 70% by weight.

10. The secondary battery according to claim 9, characterized in that, It also includes a gas diffusion layer formed in the second bending region that bends toward the second side.

11. The secondary battery according to claim 1 or 9, characterized in that, The aforementioned positive electrode uses oxygen as the positive electrode active material. The aforementioned negative electrode contains zinc.

12. The secondary battery according to claim 1 or 9, characterized in that, The aforementioned positive electrode and the aforementioned solid electrolyte are in the form of a membrane morphology consisting of a network of multiple fibers.

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