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 for attaching a frame and a current collector of a secondary battery, which can replace a gasket used in 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, each element constituting the cell module, such as a current collector, a frame, and a separator, is bonded together and an adhesive and airtight gasket is used to prevent leakage of electrolyte.

[0004] In particular, by attaching the current collector to the frame, it is necessary to stably maintain the airtightness and adhesive strength of the electrode assembly even under repeated charging and discharging of the battery and operating conditions under high pressure.To attach the current collector to the frame, a method is used in which a high pressure of 7,000 N or more is applied by using a gasket between the frame and the current collector.

[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 manufactured using rubber resin as the base resin. However, when such rubber resin is attached to a plastic frame, the difference in thermal deformation rate between the plastic material and the rubber resin causes problems such as loss of airtightness, particularly at low temperatures below -10°C and high temperatures above 40°C. Another problem is that the rubber resin has poor acid resistance when used in an acidic electrolyte solution.

[0007] Therefore, in order to solve the above limitations and problems, it is necessary to develop a method other than using a gasket to join the frame and the current collector. 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 current collector 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 a first aspect of the present invention, there is provided a secondary battery module including: 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 forming 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 first current collector and the frame are bonded together by a first adhesive member, and the second current collector and the frame are bonded together by a second adhesive member, and the first adhesive member and the second adhesive member each include an adhesive that 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): 100 cps≦V≦20,000 cps (In the above condition (2), V means the viscosity measured using a BM type viscometer at 30 rpm and 30°C.)

[0013] The pressure-sensitive adhesive may further satisfy the following condition (3). Condition (3):P (+) ≧0.5bar and P (-) ≦-0.5bar (P (+) and P (-) means the pressure at which gas begins to leak from a secondary battery module when positive and negative pressures are applied after assembling the secondary battery module including the first current collector, the frame, and the second current collector.)

[0014] Each of the first adhesive member and the second adhesive member 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.

[0015] Each of the first adhesive member and the second adhesive member 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.

[0016] The first current collector may include a first metal current collector and a first carbon current collector disposed between the first metal current collector and a frame, the second current collector may include a second metal current collector and a second carbon current collector disposed between the second metal current collector and a frame, and the first carbon current collector and the second carbon current collector may be bonded to the frame by the first adhesive member and the second adhesive member, respectively.

[0017] The first and second carbon current collectors may be coupled to a frame by being coated or adhered with a first adhesive member or a second adhesive member, respectively, on their edges.

[0018] The first adhesive member may be attached to one side of the frame in an out-of-plane direction, and the second adhesive member may be attached to the other side of the frame in the out-of-plane direction.

[0019] Each of the first adhesive member and the second adhesive member may be formed in a closed curve shape.

[0020] The frame may be formed as a hollow rectangle, and the first adhesive member and the second adhesive member may each be formed in a strip shape and arranged so that their edges match the edges of the frame.

[0021] The electrode assembly may further include a transition portion communicating between the first electrode receiving portion and the second electrode receiving portion.

[0022] The transition portion may be at least partially formed by the first adhesive member and the frame or the second adhesive member and the frame.

[0023] 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.

[0024] According to a second aspect of the present invention, it is possible to provide a secondary battery including a plurality of secondary battery modules according to the first aspect of the present invention.

[0025] The secondary battery is driven by oxidation and reduction of a redox couple dissolved in the electrolyte of the liquid electrode.

[0026] The redox couple is a vanadium redox couple. [Effects of the Invention]

[0027] 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.

[0028] 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.

[0029] The pressure-sensitive adhesive for a secondary battery of the present invention can maintain stable airtightness even under high pressure.

[0030] The adhesive for secondary batteries of the present invention has a small difference in thermal deformation rate between the current collector and 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.

[0031] 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]

[0032] [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. DETAILED DESCRIPTION OF THE INVENTION

[0033] 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.

[0034] 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.

[0035] Throughout the specification, unless specifically stated to the contrary, each element may be singular or plural.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 1, a secondary battery module according to an embodiment of the present invention may include 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, a second liquid electrode received in the second electrode receiving portion 111b and undergoing a second semi-reaction, a first adhesive member 160a connecting the first current collector 130a to the frame 110, and a second adhesive member 160b connecting the second current collector 130b to the frame 110. In this case, the secondary battery module may further include a transition portion 112 connecting the first electrode receiving portion 111a to the second electrode receiving portion 111b.

[0043] 2, the secondary battery 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 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.

[0044] Hereinafter, a more specific description will be given with reference to FIGS.

[0045] The first current collector 130a includes a first metal current collector 131a formed from metal and electrically connected to the bus bar, and a first carbon current collector 132a arranged between the first metal current collector 131a and the frame 110.

[0046] The second current collector 130b includes a second metal current collector 131b formed from metal and electrically connected to the bus bar, and a first carbon current collector 132a arranged between the second metal current collector 131b and the frame 110.

[0047] The frame 110 may include a hollow rectangular frame body 119, and may further include a frame reinforcement portion (not shown) for preventing deformation of the frame body 119.

[0048] The first metal current collector 131a and the second metal current collector 131b may be made of a metal with high electrical conductivity, such as copper or aluminum.

[0049] The first and second carbon current collectors 132a and 132b may be made of a material such as graphite, carbon, or carbon plastic, so as to have high electrical conductivity and high acid resistance.

[0050] The first carbon current collector 132a is disposed between the first liquid electrode and the first metal current collector 131a, and the second carbon current collector 132b is disposed between the second liquid electrode and the second metal current collector 131b, allowing electrons to move between them while preventing oxidation of the first metal current collector 131a and the second metal current collector 131b. The first carbon current collector 132a and the second carbon current collector 132b may be formed in the shape of a rectangular plate, or may be formed by coating the first metal current collector 131a and the second metal current collector 131b, respectively.

[0051] The first carbon current collector 132a and the second carbon current collector 132b are formed so that their edges match the edges of the frame 110. The first carbon current collector 132a and the second carbon current collector 132b are attached to the frame 110 by a first adhesive member 160a and a second adhesive member 160b, respectively. The first carbon current collector 132a and the second carbon current collector 132b have the first adhesive member 160a and the second adhesive member 160b applied or adhered to their respective edges.

[0052] In addition, the first carbon current collector 132a and the second carbon current collector 132b may be made of a material such as graphite, carbon, or carbon plastic so as to have high electrical conductivity and high acid resistance.

[0053] The first liquid electrode is an electrolyte in which an anode redox couple is dissolved. The anode redox couple may be made of 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 2+ / V 3+ The first liquid electrode is 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 can be produced 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: V5 + +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] The frame 110 is formed as a hollow rectangle. Depending on the embodiment, the frame 110 may be formed as a rhombus, circle, triangle, or polygon with pentagons or more. The frame 110 has a predetermined thickness in the out-of-plane direction and forms a first electrode receiving portion 111a and a second electrode receiving portion 111b. The frame 110 is formed so that its edges coincide with the edges of the first carbon current collector 132a of the first current collector 130a and the second carbon current collector 132b of the second current collector 130a.

[0065] The frame 110 has a first current collector 130a disposed on one side in the out-of-plane direction and a second current collector 130b disposed on the other side. The hollow of the frame 110 is closed by the first current collector 130a and the second current collector 130b. The frame 110 is disposed between the first current collector 130a and the second current collector 130b to prevent the first liquid electrode and the second liquid electrode from leaking in the in-plane direction, etc. The frame 110 is bonded to the first current collector 130a by a first adhesive member 160a and to the second current collector 130b by a second adhesive member 160b.

[0066] The frame 110 has a hollow space in which a separation membrane 120 is disposed. The hollow space in the frame 110 is divided into two spaces by the separation membrane 120. The frame 110 may be bonded to the separation membrane 120 with an adhesive having the same components as the first adhesive member 160a or the second adhesive member 160b.

[0067] The frame 110 forms a first electrode receiving portion 111a between the first current collector 130a and the separator 120, and a second electrode receiving portion 111b between the second current collector 130b and the separator 120.

[0068] The frame 110 accommodates the first and second liquid electrodes. A first adhesive member 160a is adhered to one edge of the frame 110 in the out-of-plane direction, and a second adhesive member 160b is adhered to the other edge of the frame 110 in the out-of-plane direction.

[0069] When the transition portion 112 is present, the frame 110 may form the transition portion 112 with the first adhesive member 160a and the second adhesive member 160b. The transition portion 112 connects the first electrode receiving portion 111a and the second electrode receiving portion 111b. The first liquid electrode and / or the second liquid electrode may flow through the transition portion 112. A portion of the transition portion 112 is formed as a groove extending in the in-plane direction on the edge of the frame 110, and another portion is formed as a hole extending in the out-of-plane direction.

[0070] At least a portion of the transition portion 112 may be formed by the first adhesive member 160a and the frame 110 or the second adhesive member 160b and the frame 110. The transition portion 112 may be disposed between the first adhesive member 160a and the second adhesive member 160b. One out-of-plane side of the transition portion 112 may be covered by the first adhesive member 160a and the other out-of-plane side may be covered by the second adhesive member 160b. The first liquid electrode and / or the second liquid electrode flowing through the transition portion 112 may come into contact with the first adhesive member 160a and / or the second adhesive member 160b.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] The separation membrane 120 may include perfluorinated ionomers, partially fluorinated polymers, and non-fluorinated hydrocarbons. The separation membrane 120 may be formed from or include, but is not necessarily limited to, Nafion®, Flemion®, NEOSEPTA-F®, and Gore Select®.

[0075] 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.

[0076] 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).

[0077] The first current collector 130a is disposed on one side of the frame 110 and forms a first electrode receiving portion 111a together with the frame 110 and the separator 120. The first current collector 130a is disposed parallel to and spaced apart from the second current collector 130b. The first current collector 130a is adhered to a first adhesive member 160a that is adhered to the frame 110. The first current collector 130a is connected to the frame 110 by the first adhesive member 160a. The first adhesive member 160a is coated or adhered to the edge of the first current collector 130a.

[0078] The first current collector 130a is attached with the first adhesive member 160a and does not directly contact the first or second liquid electrode flowing through the transition portion 112. The first current collector 130a is electrically connected to the first liquid electrode, and electrons move through the first current collector 130a to allow current to flow during charging and discharging.

[0079] The first current collector 130a includes a first metal current collector 131a formed from metal and electrically connected to the bus bar, and a first carbon current collector 132a arranged between the first metal current collector 131a and the frame 110.

[0080] The first carbon current collector 132a is disposed between the first liquid electrode and the first metal current collector 131a, allowing electrons to move between them while preventing oxidation of the first metal current collector 131a. The first carbon current collector 132a may be formed in the shape of a square plate or may be formed by coating on the first metal current collector 131a.

[0081] The first carbon current collector 132a is formed so that its edge matches the edge of the frame 110. The first carbon current collector 132a is attached to the frame 110 by a first adhesive member 160a. The first adhesive member 160a is applied or adhered to the edge of the first carbon current collector 132a. Thus, the first adhesive member 160a can seal the gap between the first carbon current collector 132a of the first current collector 130a and the frame 110.

[0082] Each of the first adhesive member 160a and the second adhesive member 160b may be formed in a strip shape. Each of the first adhesive member 160a and the second adhesive member 160b may be formed in a hollow rectangle. Each of the first adhesive member 160a and the second adhesive member 160b may be formed in a closed curve shape. Each of the first adhesive member 160a and the second adhesive member 160b is formed so that its edge coincides with the edge of the frame 110.

[0083] The first adhesive member 160a connects the first carbon current collector 132a of the first current collector 130a to the frame 110. The first adhesive member 160a seals the gap between the first carbon current collector 132a of the first current collector 130a and the frame 110. The first adhesive member 160a is laminated between the first carbon current collector 132a of the first current collector 130a and the frame 110. The first adhesive member 160a is adhered to one edge of the frame 110 in the out-of-plane direction. The first adhesive member 160a is adhered to the edge of one of both sides of the first carbon current collector 132a, on which the first metal current collector 131a is not disposed. The first adhesive member 160a may be applied to the first carbon current collector 132a and then adhered to the frame 110.

[0084] The first metal current collector 131a is made of a metal with high electrical conductivity, such as copper or aluminum, and may be formed in the shape of a rectangular plate, with a portion thereof protruding and connected to a bus bar.

[0085] The first metal current collector 131a may be formed as a flexible thin film or a rigid plate.

[0086] The first metal current collector 131a has a first carbon current collector 132a disposed on one side thereof. When a plurality of secondary batteries form a module as shown in Fig. 3, the first metal current collector 131a has a first carbon current collector 132a disposed on both sides thereof.

[0087] The second current collector 130b is disposed on the other side of the frame 110 and forms a second electrode receiving portion 111b together with the frame 110 and the separator 120. The second current collector 130b is disposed parallel to and spaced apart from the first current collector 130a. The second current collector 130b is adhered to a second adhesive member 160b that is adhered to the frame 110. The second current collector 130b is connected to the frame 110 by the second adhesive member 160b. The second current collector 130b has an edge that is coated or adhered with the second adhesive member 160b. Thus, the second adhesive member 160b can seal the gap between the second carbon current collector 132b of the second current collector 130b and the frame 110.

[0088] Referring to FIG. 2, the battery may further include a first solid electrode 150a and a second solid electrode 150b. The first solid electrode 150a is impregnated with a first liquid electrode and 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.

[0089] 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.

[0090] 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 .

[0091] In order to achieve the above object, a secondary battery module according to one embodiment of the present invention includes 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 forming 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 first current collector and the frame are bonded together by a first adhesive member, and the second current collector and the frame are bonded together by a second adhesive member.

[0092] The first current collector includes a first metal current collector made of metal and electrically connected to a bus bar, and a first carbon current collector disposed between the first metal current collector and the frame, while the second current collector includes a second metal current collector made of metal and electrically connected to the bus bar, and a second carbon current collector disposed between the second metal current collector and the frame.

[0093] The first and second carbon current collectors may be made of a material such as graphite, carbon, or carbon plastic, and may have high electrical conductivity and high acid resistance. The first and second carbon current collectors are attached to the frame by a first adhesive member and a second adhesive member, respectively. In this case, the first and second adhesive members may be coated or adhered to the edges of the first and second carbon current collectors, respectively.

[0094] The adhesive forming the first adhesive member and the second adhesive member can be used without any particular limitation as long as it can satisfy the same or similar airtightness as that of those bonded by a gasket, has high adhesive strength, and can ensure the stability of the battery.

[0095] According to an embodiment of the present invention, the first adhesive member and the second adhesive member may each include an adhesive that further satisfies the following condition (1) in order to exhibit excellent adhesive strength for bonding the current collector and the frame: Condition (1): A i ≧300gf / 25mm

[0096] In the above condition (1), A i means the adhesive strength measured when the pressure-sensitive adhesive is peeled 180° from the object to be adhered 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.

[0097] In the present invention, the adhesive member is used to bond a current collector and a frame. In particular, the adhesive member of the present invention can achieve excellent airtightness when it has sufficient adhesive strength between the current collector and the frame. In the present invention, the current collector is a laminate of a metal current collector and a carbon current collector. When the current collector is attached to the frame, the portion of the current collector that is attached to the frame is the carbon current collector portion. The adhesive member according to one embodiment of the present invention is easily attached to a carbon current collector made of expanded graphite or the like, but tends to be difficult to attach to a frame made of a metal or plastic material. Therefore, the adhesive of the present invention is required to exhibit excellent adhesive strength, particularly to the frame, which, as described above, is required to have an adhesive strength of at least 300 gf / 25 mm or more, and preferably 1200 gf / 25 mm or more.

[0098] For example, in the present invention, the current collector may be formed of various materials such as a metal current collector (e.g., SUS (Steel Use Stainless Steel)), a plastic current collector (e.g., polycarbonate), or a carbon-based current collector, and according to one embodiment, may be a carbon-based current collector.

[0099] In the present invention, the frame may be a metal frame or a plastic frame, and in one embodiment, it may be a plastic frame. The plastic used to form 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), preferably acrylonitrile butadiene styrene (ABS). Furthermore, the adhesive of the present invention preferably has high resistance to thermal shock by exhibiting minimal difference in thermal deformation rate not only at room temperature but also at high and low temperatures when attached to a carbon-based current collector and a plastic frame. In particular, adhesives that exhibit significantly minimal difference in thermal deformation rate and maintain airtightness at temperatures below -10°C, preferably below -20°C, and above 40°C, preferably above 50°C, may be used.

[0100] 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.

[0101] According to an embodiment of the present invention, the first adhesive member and the second adhesive member may each contain an adhesive that further satisfies the following condition (2). Condition (2): 100cps≦V≦20,000cps

[0102] In the above condition (2), V refers to the viscosity measured using a BM-type viscometer at 30 rpm and 30°C. Specifically, V is preferably adjusted to 100 cps or more and 20,000 cps or less. For example, the viscosity (V) may be 1,000 cps or more, e.g., 2,000 cps or more, 10,000 cps or more, e.g., 5,000 cps or more, and 3,000 cps or less. If the viscosity of the adhesive is excessively high, exceeding 20,000 cps, the adhesive will not be able to effectively fill the gap between the frame and the current collector, thereby failing to ensure airtightness. On the other hand, if the viscosity of the adhesive is excessively low, e.g., less than 100 cps, problems such as poor application and processability may occur.

[0103] The pressure-sensitive adhesive of the present invention has excellent airtightness, and specifically, may further satisfy the following condition (3). Condition (3):P (+) ≧0.5bar and P (-) ≦-0.5bar

[0104] 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 assembling the secondary battery module including the first current collector, frame, and second current collector. It can be seen that the larger this value, the better the airtightness can be maintained even under higher pressure.

[0105] 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.

[0106] Therefore, in order to ensure high driving stability for the secondary battery, it is preferable to satisfy the above condition (3), and the pressure at which gas leakage occurs must satisfy a positive pressure of 0.5 bar or more, 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 satisfy a negative pressure of -0.5 bar or more, and it is preferable that gas leakage does not occur even under a negative pressure of -1 bar.

[0107] 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.

[0108] Furthermore, the pressure resistance of the adhesive of the present invention must be sufficient not only at room temperature but also at high and low temperatures, and is required to maintain pressure resistance at, for example, low temperatures of -10°C or below, preferably low temperatures of -20°C, and high temperatures of, for example, 40°C or above, preferably high temperatures of 50°C.

[0109] Any adhesive that satisfies the above-described characteristics can be used without particular limitations. Specifically, each of the first adhesive member and the second adhesive member may contain 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 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.

[0110] In addition to the base resin, the pressure-sensitive adhesive of the present invention may further contain additives commonly used in this technical field, as needed. According to one embodiment, the pressure-sensitive adhesive may further contain one or more additives selected from a curing agent, an adhesion enhancer, a thickener, a diluent, and a heat resistance improver. According to one embodiment, the total amount of the additives is preferably 0.01 to 10 parts by weight based on 100 parts by weight of the base resin of the pressure-sensitive adhesive.

[0111] The method of applying the first adhesive member and the second adhesive member is not particularly limited, but specifically, each of the first adhesive member and the second adhesive member 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.

[0112] Preferably, a solvent-based pressure-sensitive adhesive can be used. Specifically, an acrylic resin can be mixed with a solvent, applied to an object to be adhered, and dried to form a pressure-sensitive adhesive. The solvent is not particularly limited as long as it is one used in the art, and can be appropriately adjusted depending on the resin selected. Examples of solvents include acetate-based solvents such as ethyl acetate and butyl acetate; aromatic solvents such as benzene, toluene, and xylene; ketone-based solvents such as acetone and methyl ethyl ketone; aliphatic hydrocarbon solvents such as n-hexane, n-haptane, and cyclohexane; and alcohol-based solvents such as methanol, ethanol, and isopropanol, which can be used alone or in combination.

[0113] For example, when a solvent-type adhesive is selected, the liquid adhesive can be mixed with a solvent, applied to an object to be adhered, and then dried to form an adhesive member. As another example, when a film-type adhesive is selected, the adhesive member can be formed by applying an adhesive solution to a carrier film such as an OPP (oriented polypropylene) film to form a double-sided adhesive tape, which is then placed between the frame and the current collector and then pressed. It is preferable to use the double-sided tape in a form that can be punched into a shape that can be adhered to the edges of the frame and the current collector.

[0114] The thickness of the adhesive member can be appropriately adjusted, and from the viewpoint of ensuring sufficient adhesive strength and minimizing the volume of the secondary battery module, the thickness of each of the first adhesive member and the second adhesive member may be, for example, 1 to 500 μm, or may be, for example, 50 to 300 μm, but is not necessarily limited thereto.

[0115] 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.

[0116] 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.

[0117] 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.

[0118] [Production Example 1: Production of adhesive] An acrylic base resin was prepared, and 100 parts by weight of the acrylic base resin was mixed with 8 parts by weight of an adhesive enhancer and 3 parts by weight of a curing agent to prepare 100 g of a solvent-based adhesive.

[0119] The acrylic base resin used was a resin composition containing an acrylic acid copolymer (2-Propenoic acid, polymer with butyl 2-propenoate, 2-ethylhexyl 2-propenoate and methyl 2-propenoate, CAS No. 98060-25-4), toluene, ethyl acetate, and acetone.

[0120] When the total amount of the acrylic base resin is 100% by weight, the acrylic acid copolymer is contained at 32% by weight, the toluene is contained at 7% by weight, the ethyl acetate is contained at 58% by weight, and the acetone is contained at 3% by weight.

[0121] The adhesive strength enhancing agent was an acrylic acid copolymer dissolved in an ethyl acetate solvent, and the curing agent was TETRAD-X (N,N,N',N'-Tetrakis(oxiranylmethyl)-1,3-benzenedimethanamine).

[0122] [Production Example 2: Production of separation membrane]

[0123] 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.

[0124] [Experimental Example] (1) Viscosity measurement The viscosity of the adhesive produced in Production Example 1 was measured using a BM type viscometer at 30 rpm and 30°C, and was found to be 2200 cps.

[0125] (2) 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 1850 gf / 25 mm.

[0126] It was confirmed that this product can achieve adhesive strength of more than 1200gf / 25mm, which is the adhesive strength that existing gaskets have to frames, specifically, adhesive strength of 1200gf / 25mm to 2000gf / 25mm.

[0127] (3) Airtightness test Two current collectors were fabricated by laminating a carbon current collector (graphite composite, thickness: 0.2 mm) and a metal current collector (aluminum foil, thickness: 0.2 mm), and these were used as the first and second current collectors, respectively.

[0128] An ABS frame (thickness: 15 mm) was prepared, and the adhesive prepared in Preparation Example 1 was applied to both sides of the ABS frame, and the two first and second current collectors prepared above were attached to the frame, respectively, so that the carbon current collector portion of the first current collector and the carbon current collector portion of the second current collector were attached to the frame.

[0129] Thereafter, a cell module including a first electrolyte solution receiving portion and a second electrolyte solution receiving portion was manufactured by disposing the separator prepared in Preparation Example 2 between a first current collector and a second current collector. 3.5+ An electrolyte (manufactured by Standard Energy) was supplied.

[0130] The cell modules were then left in constant temperature chambers at 22°C (room temperature), -20°C (low temperature), and 50°C (high temperature) for 30 days, and the presence or absence of electrolyte leakage was visually observed. Tests without electrolyte leakage were judged to be "passed," and the results are shown in Table 1 below.

[0131] [Table 1]

[0132] (4) Pressure experiment - Pressure resistance experiment Two current collectors were fabricated by laminating a carbon current collector (graphite composite, thickness: 0.2 mm) and a metal current collector (aluminum foil, thickness: 0.2 mm), and these were used as the first and second current collectors, respectively. An ABS frame was prepared, and the adhesive prepared in Preparation Example 1 was applied to both sides of the ABS frame to attach the two first and second current collectors, respectively, so that the carbon current collector portion of the first current collector and the carbon current collector portion of the second current collector were attached to the frame.

[0133] Thereafter, the separator prepared in Preparation Example 2 was disposed between a first current collector and a second current collector to prepare a cell module including a first electrolyte solution container and a second electrolyte solution container. 3.5+ An electrolyte (manufactured by Standard Energy) was supplied.

[0134] After that, a pressure of 1 bar was applied to the cell module, and a pressure gauge device (SENSYS, SMA model) was installed to check the change in pressure after leaving it for 30 days. If the pressure change rate did not exceed 50% of the initial reference pressure of 1 bar after leaving it for 30 days, it was judged to have passed.

[0135] The pressure resistance experiments were carried out in thermostatic chambers at 22° C. (normal temperature condition), −20° C. (low temperature condition), and 50° C. (high temperature condition), and the results are shown in Table 2 below.

[0136] [Table 2] [Explanation of symbols]

[0137] 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 first current collector and the frame are coupled together by a first adhesive member; the second current collector and the frame are connected by a second adhesive member; The secondary battery module, wherein the first adhesive member and the second adhesive member each contain an adhesive that satisfies the following condition (1): 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): 100cps≦V≦20,000cps In the above condition (2), V means the viscosity measured using a BM type viscometer at 30 rpm and 30°C.

3. The secondary battery module according to claim 1 , wherein the adhesive further satisfies the following condition (3): Condition (3): P （＋） ≧0.5 bar and P （－） ≦−0.5 bar The P （＋） and P （－） means the pressure at which gas starts to leak from a secondary battery module when positive and negative pressures are applied to the secondary battery module after assembling the secondary battery module including the first current collector, the frame, and the second current collector.

4. 10. The secondary battery module of claim 1, wherein each of the first adhesive member and the second adhesive member includes 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.

5. 2. The secondary battery module of claim 1, wherein each of the first adhesive member and the second adhesive member 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.

6. the first current collector includes a first metal current collector and a first carbon current collector disposed between the first metal current collector and a frame; the second current collector includes a second metal current collector and a second carbon current collector disposed between the second metal current collector and a frame; The secondary battery module of claim 1 , wherein the first and second carbon current collectors are coupled to the frame by the first and second adhesive members, respectively.

7. The secondary battery module of claim 6 , wherein a first adhesive member and a second adhesive member are respectively coated or adhered to edges of the first carbon current collector and the second carbon current collector, and are coupled to the frame.

8. the first adhesive member is attached to one side of the frame in an out-of-plane direction; The secondary battery module of claim 1 , wherein the second adhesive member is attached to the other side of the frame in an out-of-plane direction.

9. The secondary battery module of claim 1 , wherein each of the first adhesive member and the second adhesive member is formed in a closed curve shape.

10. The frame is formed as a hollow rectangle, The secondary battery module of claim 1 , wherein each of the first adhesive member and the second adhesive member is formed in a strip shape and is disposed such that an edge thereof coincides with an edge of the frame.

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

12. The secondary battery module of claim 11 , wherein the transition portion is at least partially formed by the first adhesive member and the frame or the second adhesive member and the frame.

13. 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 liquid electrode, The secondary battery module according to claim 1 , wherein the first solid electrode and the second solid electrode are disposed inside the frame.

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

15. 15. The secondary battery according to claim 14, wherein the secondary battery is driven by oxidation and reduction of a redox couple dissolved in an electrolyte of a liquid electrode.

16. 16. The secondary battery according to claim 15, wherein the redox couple is a vanadium redox couple.

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