Adhesives for secondary batteries

Abstract

The present invention relates to an adhesive for a secondary battery, and more particularly to an adhesive for a secondary battery that can replace a gasket used when assembling a cell module of a secondary battery.

Description

[Technical Field]

[0001] The present invention relates to an adhesive for a secondary battery, and more particularly to an adhesive for a secondary battery that can replace a gasket used when assembling a cell module of a secondary battery. [Background technology]

[0002] Unlike conventional secondary batteries, redox flow batteries (RFBs) are electrochemical storage devices that store electrical energy in the chemical energy of electrolytes through a system in which the active material in the electrolyte is oxidized and reduced for charging and discharging. In redox flow batteries, the actual electrochemical reaction occurs in a stack, and the battery operates by continuously circulating the electrolyte within the stack using a fluid pump. While such redox flow batteries have the advantages of long life, high output, and high capacity, they suffer from spatial limitations and design difficulties due to the need for a tank to store the electrolyte and a fluid pump to circulate the electrolyte. The inventors of the present invention therefore developed a redox secondary battery that does not require an electrolyte tank or fluid pump, but this battery suffers from low energy density and large volume.

[0003] Meanwhile, in order to assemble a cell module of a redox secondary battery, a gasket having adhesiveness and airtightness is used to connect each element of the cell module, such as a current collector, a frame, and a separator.

[0004] In particular, when the separator is attached to the frame, a gasket is used between the frame and the separator, and a high pressure of 7,000 N or more is applied.

[0005] However, there are limitations to this method, such as the disadvantage that the volume of the cell module increases due to the volume of the gasket itself, the disadvantage in the process that high pressure is required when using the gasket, the difficulty in preventing micro-leaks such as scratches on the frame surface, and the difficulty in the process of assembling and inspecting a large number of cells at once.

[0006] In addition, gaskets are generally made of rubber resin, but when such rubber resin is attached to a plastic frame, there is a problem that its airtightness is lost, especially at low temperatures below 0°C and high temperatures above 40°C, due to the difference in thermal deformation rate between the plastic material and the rubber resin. There is also a problem that it has poor acid resistance in acidic electrolyte solutions.

[0007] Therefore, in order to solve the above limitations and problems, it is necessary to develop a method other than using a gasket to bond the frame and the separator. Summary of the Invention [Problem to be solved by the invention]

[0008] SUMMARY OF THE INVENTION An object of the present invention is to provide an adhesive that can replace a gasket in a secondary battery module.

[0009] The present invention provides a secondary battery module in which a frame and a separator of a secondary battery are attached using an adhesive for replacing a gasket, and a secondary battery including the same.

[0010] The objects of the present invention are not limited to the above objects, and other objects not mentioned will be clearly understood by those skilled in the art from the following description. [Means for solving the problem]

[0011] According to one aspect of the present invention, a secondary battery module can be provided that includes a first current collector, a second current collector spaced apart from the first current collector, a separator disposed between the first current collector and the second current collector, and a frame that forms a first electrode receiving portion between the first current collector and the separator and a second electrode receiving portion between the second current collector and the separator, wherein the frame and the separator are bonded together by an adhesive, and the adhesive satisfies the following condition (1): Condition (1): A i ≧300gf / 25mm (under the above condition (1), A i means adhesive strength measured by peel force when the adhesive is peeled 180° from the adhesive object at a speed of 300 mm / min.

[0012] The pressure-sensitive adhesive may further satisfy the following condition (2). Condition (2):P (+) ≧0.5bar and P (-) ≦-0.5 bar (under the above condition (2), the P (+) and P (-) means the pressure at which gas starts to leak from the secondary battery module when positive and negative pressures are applied after the secondary battery module is assembled.

[0013] The adhesive may include at least one of an acrylate adhesive, an acrylate-ester adhesive, an acrylate-ethylene adhesive, a polycarbonate adhesive, a polyethylene adhesive, an epoxy adhesive, and an isocyanate adhesive.

[0014] The adhesive may be any one of a solvent-type adhesive, an emulsion-type adhesive, a hot-melt-type adhesive, a liquid-curing-type adhesive, and a film-type adhesive, or a combination thereof.

[0015] The frame may include a hollow rectangular frame body and a separation membrane support part formed to protrude inward from the hollow of the frame body, and the frame and the separation membrane may be coupled together at the separation membrane support part.

[0016] The separation membrane support portion may be formed in a rectangular shape on an edge portion of the frame body, protruding inward in an in-plane direction (toward the center) from a hollow portion of the frame body.

[0017] The electrode assembly may further include a transition portion communicating between the first electrode receiving portion and the second electrode receiving portion.

[0018] The transition portion may be disposed further outward in the in-plane direction than the separation membrane support portion.

[0019] The battery may further include a first adhesive member that connects the first current collector to the frame, and a second adhesive member that connects the second current collector to the frame.

[0020] The device may further include a first solid electrode disposed in the first electrode receiving portion and impregnated with a first liquid electrode, and a second solid electrode disposed in the second electrode receiving portion and impregnated with a second electrode, and the first solid electrode and second solid electrode may be disposed inside the frame.

[0021] According to another aspect of the present invention, a secondary battery including a plurality of secondary battery modules according to an aspect of the present invention can be provided.

[0022] The secondary battery may be driven by oxidation and reduction of a redox couple dissolved in an electrolyte of a liquid electrode.

[0023] The redox couple may be a vanadium redox couple. [Effects of the Invention]

[0024] The adhesive for secondary batteries of the present invention can replace conventional gaskets, thereby effectively reducing the volume of secondary battery modules, and has the advantages of high process efficiency since it does not require a high-pressure process, does not cause fine scratches on the frame surface, and allows easy inspection for each module assembly.

[0025] The pressure-sensitive adhesive for secondary batteries of the present invention is excellent in adhesive strength and airtightness between elements of a secondary battery module.

[0026] The pressure-sensitive adhesive for a secondary battery of the present invention can maintain stable airtightness even under high pressure.

[0027] The adhesive for secondary batteries of the present invention has a small difference in thermal deformation rate from the frame, and therefore has a small thermal deformation rate not only at room temperature but also at high and low temperatures, and is excellent in airtight stability.

[0028] The effects of the present invention are not limited to the above effects, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims. [Brief explanation of the drawings]

[0029] [Figure 1] 1 is an exploded perspective view of a secondary battery according to an embodiment of the present invention; [Figure 2] FIG. 10 is an exploded perspective view of a secondary battery according to another embodiment of the present invention. [Figure 3] 1 is a cross-sectional view of a secondary battery module according to an embodiment of the present invention. [Figure 4] FIG. 10 is a cross-sectional view of a secondary battery module according to another embodiment of the present invention. [Figure 5] 1 is a cross-sectional view of a secondary battery module according to an embodiment of the present invention, showing a structure including a transition portion. [Figure 6] 10 is a cross-sectional view of a secondary battery module according to another embodiment of the present invention, showing a structure including a transition portion; [Figure 7] FIG. 10 is a rear view of a frame of a secondary battery module according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0030] The advantages and features of the present invention, as well as methods for achieving them, will become clearer with reference to the following detailed embodiments in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and can be embodied in various different forms. The present embodiments are provided solely to complete the disclosure of the present invention and to enable those skilled in the art to fully understand the scope of the invention. The present invention is defined solely by the claims. The same reference numerals refer to the same elements throughout the specification.

[0031] Although terms such as "first," "second," and the like are used to describe various components, it should be understood that these components are not limited by these terms. These terms are used merely to distinguish one component from another, and it should be understood that a first component can also be a second component unless otherwise specified.

[0032] Throughout the specification, unless specifically stated to the contrary, each element may be singular or plural.

[0033] Hereinafter, when an arbitrary structure is disposed "on (or under)" a component or "above (or below)" a component, it may mean not only that the arbitrary structure is disposed in contact with the upper surface (or lower surface) of the component, but also that other structures may be interposed between the component and the arbitrary structure disposed above (or below) the component.

[0034] Furthermore, when a component is described as being "coupled," "coupled," or "connected" to another component, it should be understood that the components may be directly coupled or connected to each other, or that other components may be "intervening" between the components, or that each component may be "coupled," "coupled," or "connected" via other components.

[0035] As used herein, the singular includes the plural unless the context dictates otherwise. In this application, terms such as "comprise" or "include" should not be interpreted as including all of the various components or steps described in the specification, but should be interpreted as meaning that some of the components or steps may not be included, or that additional components or steps may be included.

[0036] Throughout the specification, "A and / or B" means A, B or A and B unless otherwise specified, and "C to D" means at least C and at most D, unless otherwise specified.

[0037] Unless otherwise specified in this specification, the terms "adhesive" and "adhesive member" are interpreted as meaning the same thing, and the adhesive itself may also be referred to as an adhesive member after being attached to a specific component of a secondary battery module.

[0038] Hereinafter, the present invention will be described in detail with reference to the drawings for explaining a secondary battery according to an embodiment of the present invention.

[0039] Referring to FIG. 1, a secondary battery module according to an embodiment of the present invention includes a first current collector 130a, a second current collector 130b spaced apart from the first current collector 130a, a separator 120 disposed between the first current collector 130a and the second current collector 130b, a frame 110 forming a first electrode receiving portion 111a and a second electrode receiving portion 111b, a first liquid electrode received in the first electrode receiving portion 111a and undergoing a first semi-reaction, and a second liquid electrode received in the second electrode receiving portion 111b and undergoing a second semi-reaction, and the frame 110 and the separator 120 may be bonded together using an adhesive.

[0040] 2, a secondary battery module according to another embodiment of the present invention may further include a first solid electrode 150a disposed in the first electrode receiving portion 111a and impregnated with a first liquid electrode, and a second solid electrode 150b disposed in the second electrode receiving portion 111b and impregnated with a second liquid electrode. The inclusion of the solid electrodes allows electrons to move more actively during charging and discharging of the secondary battery, which makes the redox reaction proceed more smoothly, thereby contributing to improved performance of the redox secondary battery.

[0041] The first solid electrode 150a is impregnated with the first liquid electrode and is disposed in the first electrode housing 111a. The first solid electrode 150a is disposed surrounded by the frame 110, the first current collector 130a, and the separator 120. The first solid electrode 150a includes a carbon-based material such as carbon or graphite felt, carbon cloth, carbon black, graphite powder, or graphene. The first solid electrode 150a is in close contact with the first current collector 130a and the separator 120.

[0042] The second solid electrode 150b is impregnated with a second liquid electrode and is disposed in the second electrode housing 111b. The second solid electrode 150b is disposed surrounded by the frame 110, the second current collector 130b, and the separation membrane 120. The second solid electrode 150b includes a carbon-based material such as carbon or graphite felt, carbon cloth, carbon black, graphite powder, or graphene. The second solid electrode 150b is disposed on the frame 110 more inward in the in-plane direction than the second adhesive member 160b.

[0043] When the first solid electrode 150 a and the second solid electrode 150 b are present, the first solid electrode 150 a and the second solid electrode 150 b are disposed inside the frame 110 .

[0044] According to an embodiment of the present invention, in order to facilitate the bonding of the frame 110 and the separator 120, a separator support part 115 may be formed on the frame 110 of the present invention, and an adhesive may be applied to the separator support part 115.

[0045] Referring to FIG. 7, specifically, a frame 110 according to an embodiment of the present invention may include a hollow rectangular frame body 119, a separation membrane support part 115 that protrudes inward from the hollow of the frame body 119 and is coupled to a separation membrane 120, and a frame reinforcement part 116 that is disposed in the hollow part of the frame body 119 and prevents the frame body 119 from deforming. In this case, the frame 110 and the separation membrane 120 may be coupled to each other at the separation membrane support part 115.

[0046] According to an embodiment of the present invention, the separation membrane support part 115 may be formed in a rectangular shape at the edge of the frame body, protruding inward (toward the center) in the in-plane direction from the hollow part of the frame body.

[0047] 5 and 6, according to an embodiment of the present invention, the electrode receiving portion 111 may further include a transition portion 112 that connects the first electrode receiving portion 111a and the second electrode receiving portion 111b. The transition portion 112 may be disposed outward in the in-plane direction from the separation membrane support portion.

[0048] According to an embodiment of the present invention, the battery may further include a first adhesive member 160a that connects the first current collector 130a to the frame 110, and a second adhesive member 160b that connects the second current collector 130b to the frame 100.

[0049] The first adhesive member 160a and the second adhesive member 160b are not particularly limited as long as they are those commonly used in the art, and may include a gasket, an adhesive, and a pressure-sensitive adhesive. For example, when the first adhesive member 160a and the second adhesive member 160b are pressure-sensitive adhesives, the same types of pressure-sensitive adhesives used to attach the separator and the frame in the present invention may be used. However, since the frame and the separator require relatively high adhesion, the pressure-sensitive adhesive may be prepared by further mixing an adhesive enhancer, a curing agent, etc.

[0050] The frame 110 may form a transition portion 112 with the first adhesive member 160a and the second adhesive member 160b.

[0051] According to one embodiment of the present invention, the first current collector 130a may include a first metal current collector 131a formed from metal and electrically connected to the bus bar, and a first carbon current collector 132a disposed between the first metal current collector 131a and the frame 110.

[0052] According to one embodiment of the present invention, the second current collector 130b may include a second metal current collector 131b formed from a metal and electrically connected to the bus bar, and a second carbon current collector 132b disposed between the second metal current collector 131b and the frame 110.

[0053] According to an embodiment of the present invention, the first liquid electrode is an electrolyte in which an anode redox couple is dissolved. The anode redox couple may be embodied using a material containing at least one of vanadium (V), zinc (Zn), bromine (Br), chromium (Cr), manganese (Mn), titanium (Ti), iron (Fe), cerium (Ce), and cobalt (Co). For example, V 2+ / V 3+ The first liquid electrode may be a redox couple. The first liquid electrode may be an acidic aqueous solution that conducts current by ionization, preferably containing sulfuric acid. In this embodiment, the first liquid electrode may be manufactured by dissolving VOSO4 (vanadylsulfate) or VO5 (vanadium pentoxide) in an H2SO4 aqueous solution.

[0054] The first liquid electrode induces the first half-reaction, which is shown below, where → indicates the discharge reaction direction and ← indicates the charge reaction direction. V 2+ ←→V 3+ +e -

[0055] During discharge, the divalent vanadium ions are oxidized to trivalent vanadium ions, and during charge, the trivalent vanadium ions are reduced to divalent vanadium ions.

[0056] The first liquid electrode is surrounded by the frame 110, the first current collector 130a, and the separator 120. The first liquid electrode is prevented from leaking in an in-plane direction by the first adhesive member 160a between the first current collector 130a and the frame 110. The first liquid electrode is accommodated in the first electrode accommodating portion 111a.

[0057] The first liquid electrode is electrically connected to the first current collector 130a, and electrons move to the first current collector 130a during discharge, and electrons from the first current collector 130a move to the first liquid electrode during charge. The first liquid electrode is in contact with the separation membrane 120, and hydrogen cations (protons) move through the separation membrane 120.

[0058] The second liquid electrode is an electrolyte in which a cathode redox couple is dissolved. The cathode redox couple may be embodied using a material containing at least one of vanadium (V), zinc (Zn), bromine (Br), chromium (Cr), manganese (Mn), titanium (Ti), iron (Fe), cerium (Ce), and cobalt (Co). In this embodiment, V is used. 4+ / V 5+ The second liquid electrode is a redox couple. The second liquid electrode may be an acidic aqueous solution that conducts current through ionization, preferably containing sulfuric acid. In this embodiment, the second liquid electrode can be fabricated by dissolving VOSO4 (vanadylsulfate) or VO5 (vanadium pentoxide) in an H2SO4 aqueous solution.

[0059] The second liquid electrode induces a second half-reaction, which is shown below, where → indicates the discharge reaction direction and ← indicates the charge reaction direction: V 5+ +e - ←→V 4+

[0060] During discharge, the vanadium pentavalent ions are reduced to vanadium tetravalent ions, and during charge, the vanadium tetravalent ions are oxidized to vanadium pentavalent ions.

[0061] The second liquid electrode is surrounded by the frame 110, the second current collector 130b, and the separation membrane 120. The second liquid electrode is prevented from leaking in the in-plane direction by the second adhesive member between the second current collector 130b and the frame 110. The second liquid electrode is housed in the second electrode housing portion 111b.

[0062] The second liquid electrode is electrically connected to the second current collector 130b, and electrons move to the second current collector 130b during charging, and electrons from the second current collector 130b move to the second liquid electrode during discharging. The second liquid electrode is in contact with the separation membrane 120, and hydrogen cations (protons) move through the separation membrane 120.

[0063] As discussed above, the first and second liquid electrodes are made of the same material. They contain vanadium ions in an electrolyte of the same material. Hereinafter, the first and second liquid electrodes will be collectively referred to as liquid electrodes.

[0064] Separation membrane 120 is disposed inside frame 110 to separate first and second liquid electrodes and allow hydrogen cations (protons) to move between the first and second liquid electrodes. Separation membrane 120 is disposed inside frame 110 to separate first electrode receiving portion 111a from second electrode receiving portion 111b.

[0065] The separation membrane 120 is disposed between the first liquid electrode and the second liquid electrode. The separation membrane 120 is disposed between the first current collector 130a and the second current collector 130b. The separation membrane 120 is disposed on the frame 110 more inward in the in-plane direction than the first adhesive member 160a and the second adhesive member 160b. The edges of the separation membrane 120 are bonded to the frame 110.

[0066] During discharge, hydrogen cations pass through the separation membrane 120 to move from the first liquid electrode to the second liquid electrode, and during charge, they pass through the separation membrane 120 to move from the second liquid electrode to the first liquid electrode.

[0067] The material forming the separation membrane 120 is not particularly limited, and may be formed from materials including, for example, perfluorinated ionomers, partially fluorinated polymers, and non-fluorinated hydrocarbons, such as Nafion®, Flemion®, NEOSEPTA-F®, and Gore Select®, but is not necessarily limited to these.

[0068] According to one embodiment, the separator 120 is made of poly(2,5-benzimidazole) (ab-PBI), poly(2,5-benzimidazole) (oPBI), poly(2,2'-(4,4'-oxybis(1,4-phenylene))-5,5'-bibenzimidazole), meta-polybenzimidazole (m-PBI), para-polybenzimidazole (p-PBI), sulfonated polybenzimidazole (s-PBI), fluorine-containing polybenzimidazole (f-PBI), or dihydroxy-2OH-PBI (dihydroxybenzoate). The separation membrane may contain a polybenzimidazole compound containing one or more polybenzimidazole monomers selected from the group consisting of polybenzimidazole (PIPBI), phenylindane-polybenzimidazole (PIPBI), and poly[(1-(4,4'-diphenylether)-5-oxybenzimidazole)-benzimidazole])-PBI-OO.

[0069] For example, the polybenzimidazole-based separation membrane of the present invention can be prepared by dissolving polybenzimidazole in an organic solvent, coating the resulting polybenzimidazole solution on a substrate film such as polyethylene terephthalate (PET), and then peeling the coating off to obtain a separation membrane, or by impregnating a porous membrane made of polyethylene (PE) and / or polypropylene (PP) with the polybenzimidazole-based solution to obtain a separation membrane. The organic solvent is selected from the group consisting of N,N-dimethylacetamide (DMAc), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and N-methyl-2-pyrrolidone (NMP).

[0070] The secondary battery module according to the present invention includes a first current collector 130a, a second current collector 130b spaced apart from the first current collector 130a, a separator 120 disposed between the first current collector 130a and the second current collector 130b, a frame 110 forming a first electrode receiving portion 111a and a second electrode receiving portion 111b, a first liquid electrode received in the first electrode receiving portion 111a and undergoing a first semi-reaction, and a second liquid electrode received in the second electrode receiving portion 111b and undergoing a second semi-reaction, and the frame 110 and the separator 120 may be bonded together using an adhesive.

[0071] The adhesive may be any adhesive that can provide the same or similar airtightness as when the frame and the separator are bonded together using an existing gasket, has high adhesive strength, and can ensure the stability of the battery.

[0072] Furthermore, existing adhesive materials such as gaskets contain chloroform and xylene-based substances, which have adverse effects on the human body and the environment, and are disadvantageous in that they increase the cost of constructing environmental facilities.

[0073] Furthermore, if a conventional adhesive is used instead of a pressure-sensitive adhesive to attach the separator, the separator may be torn or damaged when the operating environmental conditions of the secondary battery module change due to its lack of stretchability. Furthermore, adhesives have the disadvantages of being difficult to implement during the process of assembling the secondary battery module and poor reworkability due to their much shorter curing time than pressure-sensitive adhesives.

[0074] In view of this, the present invention has developed an adhesive that exhibits superior adhesive properties compared to existing gaskets or adhesives and is suitable for attaching a frame and a separator in a secondary battery module.

[0075] According to one embodiment of the present invention, the adhesive must satisfy the following condition (1). Condition (1): A i ≧300gf / 25mm

[0076] In the above condition (1), A i means the adhesive strength measured by peeling the adhesive 180° from the adhesive object at a speed of 300 mm / min, and may be 300 gf / 25 mm or more, for example, 700 gf / 25 mm or more, for example, 1,000 gf / 25 mm or more, for example, 1,200 gf / 25 mm or more, for example, 1,500 gf / 25 mm or more, or for example, 2,000 gf / 25 mm or more, and from the viewpoint of increasing adhesive strength, there is no particular upper limit, but it may be, for example, 2,500 gf / 25 mm or less.

[0077] In the present invention, the adhesive is used to bond the separator and the frame, and therefore the adhesive strength needs to be sufficient to ensure airtightness for the frame, which may be made of various materials.

[0078] In the present invention, the frame may be a metal frame or a plastic frame, and in one embodiment, may be a plastic frame. The plastic for forming the plastic frame may be a styrene-based plastic. Specific types of the plastic may be selected from polystyrene (PS), high impact polystyrene (HIPS), styrene acrylonitrile (AS), and acrylonitrile butadiene styrene (ABS), and preferably acrylonitrile butadiene styrene (ABS).

[0079] In particular, the pressure-sensitive adhesive of the present invention preferably has high resistance to temperature shock by exhibiting little difference in thermal deformation rate not only at room temperature but also at high and low temperatures when attached to a plastic frame. In particular, a pressure-sensitive adhesive that exhibits significantly little difference in thermal deformation rate at temperatures below 0°C, preferably at -10°C, and above 40°C, preferably at 50°C, and that does not lose airtightness can be used.

[0080] Meanwhile, the secondary battery module of the present invention may contain, as a liquid electrode, an acidic aqueous solution in which a redox couple is dissolved, as described below. Therefore, the pressure-sensitive adhesive of the present invention is in contact with the acidic aqueous solution for a long period of time, and thus has excellent acid resistance, thereby ensuring airtight stability.

[0081] The pressure-sensitive adhesive of the present invention is advantageous in that it can have excellent airtightness and can increase current efficiency only when airtightness is ensured. Specifically, it is preferable that the pressure-sensitive adhesive further satisfies the following condition (2): Condition (2):P (+) ≧0.5bar and P (-) ≦-0.5bar

[0082] The above P(+) and P (-) means the pressure at which gas starts to leak from the secondary battery module when positive and negative pressures are applied after the secondary battery module is assembled, and it can be seen that the larger the value, the better the airtightness can be maintained even under higher pressure.

[0083] In particular, the secondary battery module of the present invention is driven by impregnating the electrode housing of each secondary battery module with a liquid electrode without using an electrolyte tank or a fluid pump, so extremely high pressure is applied inside the secondary battery module, and the secondary battery module is required to be able to withstand a positive pressure of at least 0.5 bar. Furthermore, since the electrode housing is evacuated in the electrolyte injection process during the secondary battery manufacturing process and then a negative pressure is applied during the step of injecting the electrolyte, the secondary battery must be able to maintain its pressure resistance even under such negative pressure, and is required to be able to withstand a negative pressure of at least -0.5 bar or less.

[0084] Therefore, in order to ensure high driving stability for the secondary battery, it is preferable to satisfy the above condition (2), and the pressure at which gas leakage occurs must be 0.5 bar or more as a positive pressure, preferably 1 bar or more, more preferably 2 bar or more, and most preferably 3 bar or more. Also, the pressure at which gas leakage occurs must be -0.5 bar or more as a negative pressure, and it is preferable that gas leakage does not occur even under a negative pressure of -1 bar.

[0085] In the present invention, the criterion for satisfying pressure resistance is that after a certain pressure or more (this is referred to as the reference pressure) is first applied to the cell module of the secondary battery, and after leaving it for 30 days, there is no pressure change of 50% or more (i.e., a 50% increase or a 50% decrease) from the reference pressure.

[0086] Furthermore, the pressure resistance of the adhesive of the present invention must be satisfactory not only at room temperature but also at high and low temperatures, and is required to maintain pressure resistance at low temperatures, for example, below -0°C, preferably at low temperatures of -10°C, and at high temperatures, for example, above 40°C, preferably at high temperatures of 50°C.

[0087] The adhesive of the present invention is used as an adhesive member for attaching a separator and a frame, and the first and second electrolyte solutions of the secondary battery module of the present invention are separated by a separator. If a short circuit occurs in a unit cell during repeated charging and discharging of the secondary battery after the electrolyte solution is supplied to the secondary battery module, it may lead to safety accidents such as overheating or fire of the secondary battery. Therefore, it is an important issue that the adhesive attached to the separator and frame in the present invention does not cause a short circuit even when supported by the first or second electrolyte solution of the secondary battery.

[0088] Any adhesive that satisfies the above-mentioned characteristics can be used without particular limitation. Specifically, the adhesive may include at least one of an acrylate-based adhesive, an acrylate-ester-based adhesive, an acrylate-ethylene-based adhesive, a polycarbonate-based adhesive, a polyethylene-based adhesive, an epoxy-based adhesive, and an isocyanate-based adhesive. An acrylate-ester-based adhesive is preferred, but the adhesive is not necessarily limited to these. However, in order to improve resistance to temperature shock and acid resistance, it is preferable not to include an adhesive that contains a rubber-based resin as a base resin. The "A-based adhesive" refers to one that contains an A-based resin as a base resin.

[0089] The method of applying the pressure-sensitive adhesive is not particularly limited, and specifically, it may be any one of a solvent-type pressure-sensitive adhesive, an emulsion-type pressure-sensitive adhesive, a hot-melt-type pressure-sensitive adhesive, a liquid curing-type pressure-sensitive adhesive, and a film-type pressure-sensitive adhesive, or a combination thereof.

[0090] Preferably, a solvent-based adhesive can be used. As a specific example, an acrylic resin can be mixed with a solvent, and then applied to an object to be adhered and dried to form an adhesive.

[0091] The solvent is not particularly limited as long as it is one commonly used in the art, and can be appropriately adjusted depending on the resin selected. Examples of the solvent include acetate solvents such as ethyl acetate and butyl acetate, aromatic solvents such as benzene, toluene, and xylene, ketone solvents such as acetone and methyl ethyl ketone, aliphatic hydrocarbon solvents such as n-hexane, n-haptane, and cyclohexane, and alcohol solvents such as methanol, ethanol, and isopropanol, which can be used alone or in combination.

[0092] As another example, when a film-type adhesive is selected, a double-sided adhesive tape prepared by applying an adhesive solution to a carrier film such as an OPP (oriented polypropylene) film can be applied to the edges of the frame and separator and then pressed to adhere the tape. The double-sided tape can be easily punched into a shape that can be adhered to the edges of the frame and separator. In this case, it is preferable that the frame includes a separator support to facilitate application of the adhesive of the present invention.

[0093] The thickness of the adhesive coating or film can be appropriately adjusted, and may be, for example, 1 to 500 μm, or may be, for example, 50 to 300 μm, from the viewpoint of ensuring sufficient adhesive strength and minimizing the volume of the secondary battery module, but is not necessarily limited thereto.

[0094] A secondary battery according to another aspect of the present invention may include a plurality of secondary battery modules according to the aspect of the present invention. For example, when a plurality of secondary battery modules are formed from a plurality of frames, a plurality of first current collectors, and a plurality of second current collectors, the plurality of first current collectors are electrically connected by bus bars (not shown), and the plurality of secondary battery modules can be connected in parallel to form a secondary battery.

[0095] The secondary battery may be one that is driven by charging and discharging through oxidation and reduction of metal ions dissolved in an electrolyte, and may be, for example, a vanadium ion battery.

[0096] The present invention will be described in more detail below with reference to examples. However, the following examples are merely illustrative of the present invention, and the content of the present invention is not limited to the following examples.

[0097] [Production Example 1: Production of adhesive] 30 g of the acrylic acid copolymer was mixed with 70 g of a solvent to prepare 100 g of a solvent-based adhesive.

[0098] The acrylic acid copolymer used was a copolymer of 2-propenoic acid, ethenyl acetate, and 2-ethylhexyl 2-propenoate (Cas No. 26634-78-6).

[0099] The solvent was a mixed solvent of 33 g of toluene, 7.5 g of n-hexane, 22 g of ethyl acetate, and 7.5 g of methanol.

[0100] [Production Example 2: Production of separation membrane] m-PBI was added to dimethylacetamide (DMAC) and dissolved under stirring at 160°C and atmospheric pressure for 24 hours to prepare a PBI solution with a 12 wt% dissolution rate. A PE film (thickness: 20 μm) was then impregnated with the PBI solution and dried with hot air at 50°C for 2 minutes to obtain a separator membrane with a thickness of 27 μm.

[0101] [Manufacturing Example 3: Manufacturing of cell modules] As shown in Figure 7, a square ABS frame (thickness: 15 mm, size: 150 mm x 150 mm) was prepared, which had a separation membrane support part (width: 4 mm) protruding inward from the hollow of the frame body. The solvent-based adhesive prepared in Preparation Example 1 was applied to the separation membrane support part of the frame, and the separation membrane prepared in Preparation Example 2 was then placed and adhered thereon.

[0102] Meanwhile, two current collectors were fabricated by stacking a carbon current collector (graphite composite, thickness: 0.2 mm) and a metal current collector (aluminum foil, thickness: 0.2 mm). These were used as the first and second current collectors, respectively. The first solid electrode and the first current collector were stacked in this order on one side of the ABS frame to which the separator was attached, and the second solid electrode and the second current collector were stacked in this order on the other side of the ABS frame. When attaching the first and second current collectors, the carbon current collector portion of the first current collector and the carbon current collector portion of the second current collector were in contact with the solid electrodes and the frame, thereby producing a cell module including a first electrolyte container and a second electrolyte container.

[0103] The first electrolyte solution container and the second electrolyte solution container each contain a 1.7M concentration of V 3.5+ An electrolyte (manufactured by Standard Energy) was supplied.

[0104] [Experimental Example] (1) Adhesion measurement The adhesive prepared in Preparation Example 1 was applied to an OPP (oriented polypropylene) film and dried for 4 hours. The adhesive-coated film was attached to an ABS frame (24 mm wide x 300 mm high), and the adhesive strength was measured using a UTM (Universal Testing Machine) at a speed of 300 mm / min and a 180° peel force, resulting in a peel strength of 1100 gf / 25 mm.

[0105] It was confirmed that this could achieve adhesive strength of more than 1000gf / 25mm, which is the adhesive strength that existing gaskets have to frames.

[0106] (2) Adhesion environment experiment The (+) and (-) terminals of a FLUKE-101 multimeter were connected to the metal current collector of the first current collector and the metal current collector of the second current collector, respectively, in a constant temperature chamber at 22°C (room temperature), 0°C (low temperature), and 50°C (high temperature) for three hours each, and the occurrence of a short circuit was confirmed. Poor adhesion between the separator and the attachment surface of the frame, or rupture or damage to the separator due to the above conditions, can lead to a short circuit between the two electrodes (first electrode and second electrode). Therefore, the attachment state of the separator can be estimated by checking for the occurrence of a short circuit.

[0107] The FLUKE-101 multimeter device emits a beeping alarm when a short circuit occurs, allowing users to check whether a short circuit has occurred. The results are shown in Table 1 below.

[0108] After leaving it for 3 hours, the separation membrane and frame were visually inspected to see if they were still attached in their original state. If they remained in the same state as before, they were judged to be "passed." The results are shown in Table 1 below.

[0109] [Table 1]

[0110] If the separator is properly attached, the first and second electrodes are separated, preventing a short circuit even when a current is passed through them. However, if the separator is not properly attached, the first and second electrodes are directly connected to each other, resulting in a short circuit.

[0111] As shown in Table 1 above, when a separator was attached using the adhesive of the present invention, no short circuit occurred even after being left at room temperature, low temperature, and high temperature for 3 hours, and it was confirmed that the attachment state remained the same as the original state. [Explanation of symbols]

[0112] 110: Frame 111a: First electrode housing section 111b: second electrode housing section 112: Transition part 114: Inlet 115: Separation membrane support part 119: Frame body 120: Separation membrane 130a: First current collector 130b: second current collector 131a: First metal current collector 131b: second metal current collector 132a: First carbon current collector 132b: Second carbon current collector 150a: 1st solid electrode 150b: 2nd solid electrode 160a: First adhesive member 160b: second adhesive member

Claims

1. A first current collector; a second current collector disposed spaced apart from the first current collector; a separator disposed between the first current collector and the second current collector; a frame that forms a first electrode receiving portion between the first current collector and the separator, and a second electrode receiving portion between the second current collector and the separator, The frame and the separator are bonded together by an adhesive, The pressure-sensitive adhesive satisfies the following condition (1): Secondary battery module. Condition (1): A ｉ ≧300gf / 25mm In the above condition (1), A ｉ means adhesive strength measured by peel force when the adhesive is peeled from the adhesive object at a speed of 300 mm / min at an angle of 180°.

2. The secondary battery module according to claim 1 , wherein the adhesive further satisfies the following condition (2): Condition (2): P （＋） ≧0.5 bar and P （－） ≦−0.5 bar In the above condition (2), P （＋） and P （－） means a pressure at which gas starts to leak from the secondary battery module when positive and negative pressures are applied after the secondary battery module is assembled.

3. 10. The secondary battery module of claim 1, wherein the adhesive comprises at least one of an acrylate-based adhesive, an acrylate-ester-based adhesive, an acrylate-ethylene-based adhesive, a polycarbonate-based adhesive, a polyethylene-based adhesive, an epoxy-based adhesive, and an isocyanate-based adhesive.

4. The secondary battery module according to claim 1 , wherein the adhesive is any one of a solvent-type adhesive, an emulsion-type adhesive, a hot-melt-type adhesive, a liquid-curing-type adhesive, and a film-type adhesive, or a combination thereof.

5. The frame includes a hollow rectangular frame body and a separation membrane support part formed to protrude inward from the hollow of the frame body, The secondary battery module of claim 1 , wherein the separator supports couple the frame and the separator.

6. The secondary battery module according to claim 5 , wherein the separator support portion protrudes inward (toward the center) in an in-plane direction from a hollow portion of the frame body and is formed in a rectangular shape on an edge portion of the frame body.

7. The secondary battery module of claim 1 , further comprising a transition portion communicating the first electrode receiving portion and the second electrode receiving portion.

8. The secondary battery module according to claim 7 , wherein the transition portion is disposed further outward in an in-plane direction than the separator support portion.

9. The secondary battery module of claim 1 , further comprising: a first adhesive member connecting the first current collector and the frame; and a second adhesive member connecting the second current collector and the frame.

10. The liquid crystal display device further includes a first solid electrode disposed in the first electrode receiving portion and impregnated with a first liquid electrode, and a second solid electrode disposed in the second electrode receiving portion and impregnated with a second electrode, The secondary battery module according to claim 1 , wherein the first solid electrode and the second solid electrode are disposed inside the frame.

11. A secondary battery comprising a plurality of secondary battery modules according to claim 1 .

12. 12. The secondary battery according to claim 11, wherein the secondary battery is driven by oxidation and reduction of a redox couple dissolved in an electrolyte of a liquid electrode.

13. The secondary battery according to claim 12 , wherein the redox couple is a vanadium redox couple.

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