Secondary battery

Abstract

The present invention relates to a secondary battery that is charged and discharged through oxidation and reduction of metal ions dissolved in an electrolyte. The secondary battery according to an embodiment of the present invention comprises: a first liquid electrode in which a first half reaction occurs; a second liquid electrode in which a second half reaction occurs; and a separator disposed between the first liquid electrode and the second liquid electrode, wherein the separator comprises a first separator and a second separator disposed to face the first separator so as to form a space therebetween.

Description

secondary battery

[0001] The present invention relates to a secondary battery, and more specifically, to a secondary battery in which metal ions dissolved in an electrolyte are oxidized and reduced to charge and discharge.

[0002] Unlike conventional rechargeable batteries, a Redox Flow Battery (RFB) is an electrochemical storage device that stores electrical energy as chemical energy in the electrolyte, utilizing a system where active materials within the electrolyte undergo oxidation and reduction for charging and discharging. In a Redox Flow Battery, the actual electrochemical reaction takes place in the stack, and the battery operates by continuously circulating the electrolyte within the stack using a fluid pump. While such Redox Flow Batteries offer advantages such as a long lifespan, high output, and high capacity, they have faced issues related to spatial constraints and design difficulties due to the electrolyte storage tank and the fluid pump required to circulate the electrolyte. Accordingly, the inventors of this invention developed a Redox rechargeable battery that eliminates the electrolyte tank and fluid pump; however, this resulted in electrical loss due to self-discharge caused by active materials passing through the separator during the rest period after charging.

[0003] The problem that the present invention aims to solve is to provide a secondary battery with an improved self-discharge rate.

[0004] The problems of the present invention are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below.

[0005] To achieve the above objective, a secondary battery according to an embodiment of the present invention comprises a first liquid electrode in which a first half-reaction occurs, a second liquid electrode in which a second half-reaction occurs, and a plurality of separators arranged to overlap each other between the first liquid electrode and the second liquid electrode, with a space formed between them.

[0006] To achieve the above objective, a secondary battery according to an embodiment of the present invention comprises a first current collector, a second current collector spaced apart from the first current collector, a plurality of separators spaced between the first current collector and the second current collector, a first liquid electrode spaced between the first current collector and the separator and electrically connected to the first current collector, and a second liquid electrode spaced between the second current collector and the separator and electrically connected to the second current collector and electrically connected to the second current collector, wherein the plurality of separators stores a portion of the first liquid electrode and / or the second liquid electrode.

[0007] To achieve the above objective, a secondary battery according to an embodiment of the present invention comprises: a first liquid electrode in which a first half-reaction occurs and is electrically connected to the first current collector; a first separator spaced apart from the first current collector and forming a space in which the first liquid electrode is stored; a second current collector; a second liquid electrode in which a second half-reaction occurs and is electrically connected to the second current collector; and a second separator spaced apart from the second current collector and forming a space in which the second liquid electrode is stored, wherein the first separator and the second separator are arranged overlappingly and a space is formed between them.

[0008] Specific details of other embodiments are included in the detailed description and drawings.

[0009] According to the secondary battery of the present invention, one or more of the following effects are present.

[0010] First, using multiple membranes has the advantage of suppressing the permeation of vanadium 2 ions through the membranes.

[0011] Second, there is also the advantage that the self-discharge rate is improved as a portion of the liquid electrode is stored in the space between multiple separators.

[0012] Third, by using thin membranes in layers, there is an advantage of increased Coulomb efficiency and reduced costs compared to using a single thick membrane.

[0013] Fourth, there is also the advantage of preventing damage to the separator even when thin separators are stacked.

[0014] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description in the claims.

[0015] FIG. 1 is a perspective view of a secondary battery according to one embodiment of the present invention.

[0016] FIG. 2 is a 2-2 cross-sectional view of the secondary battery shown in FIG. 1.

[0017] FIG. 3 is a diagram showing that self-discharge is suppressed by the passage of an active material through a separator in a secondary battery according to one embodiment of the present invention.

[0018] FIG. 4 is a partial cross-sectional view of a secondary battery according to another embodiment of the present invention.

[0019] FIG. 5 is a partial cross-sectional view of a secondary battery according to another embodiment of the present invention.

[0020] FIG. 6 is a partial cross-sectional view of a secondary battery according to another embodiment of the present invention.

[0021] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Throughout the specification, the same reference numerals refer to the same components.

[0022] Although terms such as "first," "second," etc., are used to describe various components, it goes without saying that these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless specifically stated otherwise, the first component may also be the second component.

[0023] Throughout the specification, unless specifically stated otherwise, each component may be singular or plural.

[0024] In the following, the statement that any configuration is placed on the "upper (or lower)" of a component or on the "upper (or lower)" of a component may mean not only that any configuration is placed in contact with the upper (or lower) surface of said component, but also that another configuration may be interposed between said component and any configuration placed on (or below) said component.

[0025] In addition, where it is stated that one component is "connected," "combined," or "connected" to another component, it should be understood that while the components may be directly connected or connected to each other, another component may be "interposed" between each component, or each component may be "connected," "combined," or "connected" through another component.

[0026] Singular expressions used in this specification include plural expressions unless the context clearly indicates otherwise. In this application, terms such as "composed of" or "comprising" should not be interpreted as necessarily including all of the various components or steps described in the specification, and should be interpreted as meaning that some of the components or steps may be omitted or additional components or steps may be included.

[0027] Throughout the specification, "A and / or B" means A, B, or A and B unless specifically stated otherwise, and "C to D" means C or more and D or less unless specifically stated otherwise.

[0028] Hereinafter, the present invention will be described with reference to the drawings for explaining a secondary battery according to embodiments of the present invention.

[0029] FIG. 1 is a perspective view of a secondary battery according to one embodiment of the present invention, and FIG. 2 is a cross-sectional view in the 2-2 direction of the secondary battery shown in FIG. 1.

[0030] A secondary battery according to one embodiment of the present invention comprises: a first current collector (130a); a second current collector (130b) spaced apart from the first current collector (130a); a plurality of separators (120) mutually overlapping and arranged between the first current collector (130a) and the second current collector (130b); a first electrode storage portion (111a) formed between the first current collector (130a) and the separator (120); a second electrode storage portion (111b) formed between the second current collector (130b) and the separator (120); a frame (110) that fixes the plurality of separators (120) and forms the first electrode storage portion (111a) and the second electrode storage portion (111b); and a first electrode that is stored in the first electrode storage portion (111a) and in which a first half reaction occurs. It includes a liquid electrode (140a) and a second liquid electrode (140b) stored in a second electrode storage unit (111b) where a second half reaction occurs.

[0031] The first liquid electrode (140a) is an electrolyte in which an anode active material is dissolved. The anode active material may be implemented as a material comprising at least one of vanadium (V), zinc (Zn), bromine (Br), chromium (Cr), manganese (Mn), titanium (Ti), iron (Fe), cerium (Ce), and cobalt (Co), and in this embodiment, the anode active material is a vanadium ion (V) having an oxidation state of +2 or +3. 2+ / V 3+ The electrolyte of the first liquid electrode (140a) may be an acidic storage solution that conducts current through ionization, and preferably contains sulfuric acid. In this embodiment, the first liquid electrode (140a) may be prepared by dissolving VOSO4 (vanadylsulfate) or V2O5 (vanadium pentoxide) in an H2SO4 storage solution.

[0032] The first liquid electrode (140a) causes the first half-reaction. The first half-reaction is as follows, where → indicates the direction of the discharge reaction and ← indicates the direction of the charge reaction.

[0033] V 2+←→ V 3+ + e -

[0034] During discharge, vanadium divalent ions are oxidized to vanadium trivalent ions, and during charging, vanadium trivalent ions are reduced to vanadium divalent ions.

[0035] The first liquid electrode (140a) is provided surrounded by a frame (110), a first current collector (130a), and a first separator (120a). The first liquid electrode (140a) is stored in a first electrode storage unit (111a). The first liquid electrode (140a) may be impregnated into a block composed of carbon-based materials such as carbon or graphite felt, carbon cloth, carbon black, graphite powder, or graphene, or may be a slurry mixed with powder of the aforementioned carbon-based materials.

[0036] The first liquid electrode (140a) is positioned between the first current collector (130a) and the first separator (120a). The first liquid electrode (140a) is electrically connected to the first current collector (130a), so that electrons move to the first current collector (130a) during discharge, and electrons from the first current collector (130a) move to the first liquid electrode (140a) during charging. The first liquid electrode (140a) is in contact with the separator (120), and hydrogen cations (protons) move through the separator (120).

[0037] The second liquid electrode (140b) is an electrolyte in which a cathode active material is dissolved. The cathode active material may be implemented as a material comprising at least one of vanadium (V), zinc (Zn), bromine (Br), chromium (Cr), manganese (Mn), titanium (Ti), iron (Fe), cerium (Ce), and cobalt (Co), and in this embodiment, the cathode active material is a vanadium ion (V) having an oxidation state of +4 or +5. 4+ / V 5+The electrolyte of the second liquid electrode (140b) may be an acidic storage solution that conducts current through ionization, and preferably contains sulfuric acid. In this embodiment, the second liquid electrode (140b) may be prepared by dissolving VOSO4 (vanadylsulfate) or V2O5 (vanadium pentoxide) in an H2SO4 storage solution.

[0038] The second liquid electrode (140b) causes a second half-reaction. The second half-reaction is as follows, where → indicates the direction of the discharge reaction and ← indicates the direction of the charge reaction.

[0039] V 5+ + e - ←→ V 4+

[0040] During discharge, vanadium pentavalent ions are reduced to vanadium tetravalent ions, and during charging, vanadium tetravalent ions are oxidized to vanadium pentavalent ions.

[0041] The second liquid electrode (140b) is provided surrounded by a frame (110), a second current collector (130b), and a second separator (120b). The second liquid electrode (140b) may be impregnated into a block composed of carbon-based materials such as carbon or graphite felt, carbon cloth, carbon black, graphite powder, or graphene, or may be a slurry mixed with powder of the aforementioned carbon-based materials.

[0042] The second liquid electrode (140b) is positioned between the second current collector (130b) and the second separator (120b). The second liquid electrode (140b) is electrically connected to the second current collector (130b), so that electrons move to the second current collector (130b) during charging, and electrons from the second current collector (130b) move to the second liquid electrode (140b) during discharging. The second liquid electrode (140b) is in contact with the separator (120), and hydrogen cations (protons) move through the separator (120).

[0043] As previously described, the first liquid electrode (140a) and the second liquid electrode (140b) have the same composition. The first liquid electrode (140a) and the second liquid electrode (140b) contain an active material (vanadium ion) with a different oxidation state in an electrolyte of the same composition. Hereinafter, the first liquid electrode (140a) and the second liquid electrode (140b) will be collectively referred to as the liquid electrode.

[0044] The frame (110) is formed as a hollow square. According to the embodiment, the frame (110) may be formed as a rhombus, a circle, a triangle, or a polygon of pentagon or more. The frame (110) has a predetermined thickness in the out-of-plane direction to form a first electrode storage portion (111a) between the first current collector (130a) and the first separator (120a), and to form a second electrode storage portion (111b) between the second current collector (130b) and the second separator (120b).

[0045] A first collector (130a) is disposed on one side of the frame (110) in the out-of-plane direction and a second collector (130b) is disposed on the other side. The hollow of the frame (110) is closed by the first collector (130a) and the second collector (130b).

[0046] The frame (110) supports a plurality of separator membranes (120). A rib is formed in the frame (110) that protrudes inward from the hollow, and a plurality of separator membranes (120) are bonded and fixed to the rib of the frame (110) with an adhesive.

[0047] According to an embodiment, the frame (110) may be composed of two parts. The frame (110) may include a first frame forming a first electrode storage portion (111a) and a second frame forming a second electrode storage portion (111b). The edges of a plurality of separators (120) may be interlocked and fixed between the first frame and the second frame.

[0048] The first current collector (130a) is positioned on one side of the frame (110) to form a first electrode storage unit (111a) together with the frame (110) and the first separator (120a). The first current collector (130a) is positioned parallel to and spaced apart from the second current collector (130b). The first current collector (130a) is coupled to the frame (110). The first current collector (130a) is electrically connected to the first liquid electrode (140a) so that electrons move to allow current to flow during charging and discharging.

[0049] The first current collector (130a) includes a metal current collector formed of a metal such as copper or aluminum and electrically connected to a busbar, and a carbon current collector formed of a material such as graphite, carbon, carbon plastic, etc. The carbon current collector allows electrons to move between the first liquid electrode (140a) and the metal current collector, while preventing the metal current collector from being oxidized. The carbon current collector may be adhered to or coated on the metal current collector.

[0050] The second current collector (130b) is positioned on the other side of the frame (110) (opposite side to the side where the first current collector (130a) is positioned) to form a second electrode storage unit (111b) together with the frame (110) and the second separator (120b). The second current collector (130b) is positioned parallel to the first current collector (130a) and spaced apart from it. The second current collector (130b) is coupled to the frame (110). The second current collector (130b) is electrically connected to the second liquid electrode (140b) so that electrons move to allow current to flow during charging and discharging.

[0051] The second current collector (130b) includes a metal current collector formed of a metal such as copper or aluminum and electrically connected to a busbar, and a carbon current collector formed of a material such as graphite, carbon, carbon plastic, etc. The carbon current collector allows electrons to move between the second liquid electrode (140b) and the metal current collector, while preventing the metal current collector from being oxidized. The carbon current collector may be adhered to or coated on the metal current collector.

[0052] The first electrode storage unit (111a) is a space in which the first liquid electrode (140a) is stored, and is formed between the first current collector (130a) and the first separator (120a).

[0053] The second electrode storage unit (111b) is a space where the second liquid electrode (140b) is stored, and is formed between the second current collector (130b) and the second separator (120b).

[0054] A plurality of separators (120) are arranged inside the frame (110) to separate the first liquid electrode (140a) and the second liquid electrode (140b) and to allow hydrogen cations (protons) to move between the first liquid electrode (140a) and the second liquid electrode (140b). The plurality of separators (120) distinguish the first electrode storage unit (111a) and the second electrode storage unit (111b).

[0055] A plurality of separators (120) are disposed between the first liquid electrode (140a) and the second liquid electrode (140b). A plurality of separators (120) are disposed between the first current collector (130a) and the second current collector (130b). A plurality of separators (120) are fixed to the frame (110).

[0056] During discharge, hydrogen cations pass through a plurality of separators (120) and move from the first liquid electrode (140a) to the second liquid electrode (140b), and during charging, pass through a plurality of separators (120) and move from the second liquid electrode (140b) to the first liquid electrode (140a).

[0057] A plurality of separators (120) store a portion of the first liquid electrode (140a) and / or the second liquid electrode (140b). The plurality of separators (120) store the liquid electrodes to prevent self-discharge that occurs when the active material of the first electrode storage unit (111a) or the second electrode storage unit (111b) passes through the plurality of separators (120).

[0058] Multiple separation membranes (120) are arranged overlapping each other to form a space (111s) between them.

[0059] A plurality of separator membranes (120) according to one embodiment of the present invention includes a first separator membrane (120a) and a second separator membrane (120b) that is overlapped with the first separator membrane (120a) and has a space (111s) formed between them.

[0060] In this embodiment, the first separator (120a) and the second separator (120b) are ion-selective polymers. The first separator (120a) and the second separator (120b) are preferably polybenzimidazole (PBI)-based polymers, for example, ab-PBI (Poly(2,5-benzimidazole)), O-PBI (Poly[2,2'-(4,4'-oxybis(1,4-phenylene))-5,5'-bibenzimidazole), m-PBI (meta-polybenzimidazole), p-PBI (para-polybenzimidazole), s-PBI (sulfonated polybenzimidazole), f-PBI (fluorine-containing polybenzimidazole), 2OH-PBI (Dihydroxy polybenzimidazole), PIPBI (Phenylindane-polybenzimidazole), PBI-OO (poly[(1-(4,4'-diphenylether)-5-oxybenzimidazole)-benzimidazole]), It may be one or more mixtures or copolymers selected from the group comprising Py-PBI (poly[2,2'-(2,6-pyridine)-5,5'-bibenzimidazole]), biphenyl-PBI (biphenyl-linked polybenzimidazole), terphenyl-PBI (terphenyl-linked polybenzimidazole), and HMT-PBI (poly[2,2'-(2,2'',4,4'',6,6''-hexamethyl-p-terphenyl-3,3''-diyl)-5,5'-bibenzimidazole]), but is not necessarily limited thereto.

[0061] In addition, fluorine-based polymers may be composed of ion-selective polymers, examples of which include Nafion (DuPont), Flemion (Ashahi Kasei), Fumasep (Fumatech), Ballard Advanced (Ballard), Gore-Select (Gore), Aciplex (Ashahi Glass), and Aquivion (Solvay).

[0062] The first separator (120a) forms the first current collector (130a) and the first electrode storage unit (111a). The first separator (120a) is in contact with the first liquid electrode (140a). The second separator (120b) forms the second current collector (130b) and the second electrode storage unit (111b). The second separator (120b) is in contact with the second liquid electrode (140b).

[0063] A space (111s) is formed between the first separator (120a) and the second separator (120b). A portion of the first liquid electrode (140a) and / or the second liquid electrode (140b) is stored in the space (111s) between the first separator (120a) and the second separator (120b).

[0064] During charging or discharging, a crossover phenomenon may occur in which the first liquid electrode (140a) passes through the first separator (120a) or the second liquid electrode (140b) passes through the second separator (120b). Accordingly, a portion of the first liquid electrode (140a) or the second liquid electrode (140b) is stored in the space (111s) between the first separator (120a) and the second separator (120b). The active material stored in the space (111s) between the first separator (120a) and the second separator (120b) has an oxidation number of +3.x to +4.x (V 3+ / V 4+ )am.

[0065] FIG. 3 is a diagram showing that self-discharge is suppressed by the passage of an active material through a separator in a secondary battery according to one embodiment of the present invention.

[0066] During the resting period after the charging reaction is completed at the first liquid electrode (140a) and the second liquid electrode (140b), vanadium ions (V) with an oxidation state of +2, which are the active material of the first liquid electrode (140a), 2+ Even if ) passes through the first separation membrane, vanadium ions (V) having an oxidation number of +3.x to +4.x in the space (111s) 3+ / V 4+ The probability of it passing through the second separator (120b) is significantly reduced as it is oxidized to )

[0067] That is, after the charging reaction is completed at the first liquid electrode (140a) and the second liquid electrode (140b), the vanadium ions that passed through the first separator (120a) exist in an oxidized state in the space (111s), thereby improving the self-discharge rate.

[0068] During the resting period after the charging reaction is completed at the first liquid electrode (140a) and the second liquid electrode (140b), vanadium ions (V) having an oxidation state of +4 to +5, which are the active material of the second liquid electrode (140b), 4+ / V 5+ Even if ) passes through the second separator (120b), vanadium ions (V) having an oxidation number of +3.x to +4.x in the space (111s) 3+ / V 4+ It is reduced to ) and the probability of passing through the second separation membrane (120b) is significantly reduced.

[0069] That is, the self-discharge rate is improved by the vanadium ions that passed through the second separator (120b) after the charging reaction is completed at the first liquid electrode (140a) and the second liquid electrode (140b) existing in a reduced state in the space (111s).

[0070] After the charging reaction is completed at the first liquid electrode (140a) and the second liquid electrode (140b), the oxidation number of the active material present in the space (111s) is between the oxidation number of the active material of the first liquid electrode (140a) (+2) and the oxidation number of the active material of the second liquid electrode (140b) (+5).

[0071] FIG. 4 is a partial cross-sectional view of a secondary battery according to another embodiment of the present invention.

[0072] According to another embodiment of the present invention, a plurality of separators (220) of a secondary battery are formed by sequentially stacking three separators.

[0073] A plurality of separators (220) of a secondary battery according to another embodiment of the present invention include a first separator (220a), a second separator (220b) arranged overlapping the first separator (220a) to form a space (211s) between them, and a third separator (220c) arranged overlapping the second separator (220b) to form a space (211s) between them.

[0074] In this embodiment, the spaces (211s) are formed in plurality between the plurality of separators (220), and the plurality of spaces (211s) are arranged in a direction in which the plurality of separators (220) overlap.

[0075] Table 1 below shows the experimental results for self-discharge rate and Coulombic efficiency (CE) when a single separator is used and when multiple separators are used to form a space.

[0076] Coulomb efficiency (CE) was calculated by measuring the charge capacity after charging to 1.55V with a current of 0.5 C, and measuring the discharge capacity after discharging to 1.1V with a current of 0.5 C without a rest period.

[0077] The self-discharge rate was calculated by charging with a current of 0.5 C until it reached 1.55 V, and then proceeding with a rest period of 48 hours after charging was complete, as the difference between the voltage after 10 hours and the voltage after 40 hours.

[0078] Separator Thickness (㎛) CE (%) Self-discharge Rate (mV / h) Example 114 (7㎛ 2 sheets) 99.7 0.221 Example 221 (7㎛ 3 sheets) 99.8 0.204 Comparative Example 120 99.6 0.257 Comparative Example 27 99.2 0.340

[0079] Example 1 is a secondary battery using two separators with a thickness of 7 μm, as in one embodiment of the present invention of FIG. 2, and Example 2 is a secondary battery using three separators with a thickness of 7 μm, as in another embodiment of the present invention of FIG. 4.

[0080] Comparative Example 1 is a secondary battery using one separator with a thickness of 20 μm, and Comparative Example 2 is a secondary battery using one separator with a thickness of 7 μm.

[0081] The self-discharge rate of Example 1, which consists of two separators, is 0.221 mV / h, which is an improved self-discharge rate compared to Comparative Example 1, which consists of one separator, at 0.257 mV / h, and Comparative Example 2, which consists of 0.340 mV / h. In addition, Example 2, which consists of three separators with a thickness of 7 μm and a total separator thickness of 21 μm, has a self-discharge rate of 0.204 mV / h, which is an improved value compared to Comparative Example 1, which uses one separator with a thickness of 20 μm. Therefore, it is desirable to use two or more separators stacked together.

[0082] In addition, when comparing the Coulomb efficiency (CE), the CE of Example 1, which uses two membranes, is 99.7%, and the CE of Example 2, which uses three membranes, is 99.8%, which is higher than the CE of Comparative Example 1, which uses one membrane, at 99.6%, and Comparative Example 2, at 99.2%. In addition, when comparing the Coulomb efficiency (CE), the CE of Example 1, which uses two membranes, is 99.7%, and the CE of Example 2, which uses three membranes, is 99.8%, which is higher than the CE of Comparative Example 1, which uses one membrane, at 99.6%, and Comparative Example 2, at 99.2%. Through this, it was confirmed that there is no problem with the movement of hydrogen cations through the membranes even when multiple membranes are stacked and used.

[0083] FIG. 5 is a partial cross-sectional view of a secondary battery according to another embodiment of the present invention.

[0084] A plurality of separators (320) of a secondary battery according to another embodiment of the present invention include a first separator (320a) and a second separator (320b) which is arranged overlapping the first separator (320a) and has a plurality of spaces (311s) formed between it and the first separator (320a).

[0085] The first separator (320a) and the second separator (320b) are partially bonded or bonded to each other to form a plurality of spaces (311s). The plurality of spaces (311s) are spaced apart on the plane formed by the separator (320). It is preferable that the plurality of spaces (311s) be uniformly formed between the plurality of separators (320).

[0086] As shown in FIG. 2, when thin separators are stacked, an excessive amount of liquid electrodes may flow into the space between the separators, causing the separators to be damaged, and the liquid electrodes may be stored unevenly, which may reduce the self-discharge prevention effect. Accordingly, as in another embodiment of the present invention, it is desirable to form a plurality of spaces (311s) by partially adhering or bonding a plurality of separators (320) to each other, thereby preventing damage to the separators (320) and allowing the liquid electrodes to be stored uniformly.

[0087] FIG. 6 is a partial cross-sectional view of a secondary battery according to another embodiment of the present invention.

[0088] A plurality of separators (420) of a secondary battery according to another embodiment of the present invention include a first separator (420a) and a second separator (420b) that is overlapped with the first separator (420a) and has a space (411s) formed between them, wherein each of the first separator (420a) and the second separator (420b) may be formed by applying an ion-selective polymer layer (421a, 421b) to one surface of a porous substrate layer (423a, 423b). That is, the first separator (420a) is formed by applying a first ion-selective polymer layer (421a) to one surface of the first porous substrate layer (423a), and the second separator (420b) is formed by applying a second ion-selective polymer layer (421b) to one surface of the second porous substrate layer (423b).

[0089] As shown in Figure 2, when thin separators are stacked, the liquid electrode may flow excessively into the space between the separators, causing the separators to break. Therefore, the breakage of the separators can be prevented by applying an ion-selective polymer layer to a porous substrate layer with high mechanical strength.

[0090] The porous substrate layer (423a, 423b) and the ion-selective polymer layer (421a, 421b) are not clearly separated into two layers, and in the inter-layer there may be a layer in which the ion-selective polymer layer (421a, 421b) is impregnated into the porous substrate layer (423a, 423b).

[0091] The ion-selective polymer layer (421a, 421b) is preferably a polybenzimidazole (PBI)-based polymer having excellent ion selectivity and excellent impregnation and coating properties on a polyolefin-based polymer substrate, for example, ab-PBI (Poly(2,5-benzimidazole)), O-PBI (Poly[2,2'-(4,4'-oxybis(1,4-phenylene))-5,5'-bibenzimidazole), m-PBI (meta-polybenzimidazole), p-PBI (para-polybenzimidazole), s-PBI (sulfonated polybenzimidazole), f-PBI (fluorine-containing polybenzimidazole), 2OH-PBI (Dihydroxy polybenzimidazole), PIPBI (Phenylindane-polybenzimidazole), It may be one or more mixtures or copolymers selected from the group comprising PBI-OO(poly[(1-(4,4'-diphenylether)-5-oxybenzimidazole)-benzimidazole]), Py-PBI(poly[2,2'-(2,6-pyridine)-5,5'-bibenzimidazole]), biphenyl-PBI(biphenyl-linked polybenzimidazole), terphenyl-PBI(terphenyl-linked polybenzimidazole), and HMT-PBI(poly[2,2'-(2,2'',4,4'',6,6''-hexamethyl-p-terphenyl-3,3''-diyl)-5,5'-bibenzimidazole]), but is not necessarily limited thereto.

[0092] It is preferable that the porous substrate layer (423a, 423b) be a material that exhibits high tensile strength (e.g., 100 MPa or more) even with a thin thickness, and has excellent impregnation and coating properties of polybenzimidazole-based polymers. It is preferable that the porous substrate layer (423a, 423b) be a polyolefin-based polymer substrate such as polyethylene (PE) or polypropylene (PP), and depending on the example, it may be a fluorine-based resin such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), or polychlorotrifluoroethylene (PCTFE), or a copolymer or mixture of one or more of polysulfone (PSU), polyethersulfone (PES), polyimide (PI), or polyetherimide (PEI).

[0093] The first separator (420a) and the second separator (420b) are arranged facing each other so that their respective ion-selective polymer layers (421a, 421b) face each other. A space (411s) is formed between the first ion-selective polymer layer (421a) and the second ion-selective polymer layer (421b). A portion of the first liquid electrode (140a) and / or the second liquid electrode (140b) is stored between the first ion-selective polymer layer (421a) and the second ion-selective polymer layer (421b).

[0094] In this embodiment, the first separator (420a) and the second separator (420b) are joined by heat-fusion at their edges. Heat and pressure are applied to the edges of the first porous substrate layer (423a) and the second porous substrate layer (423b) to fuse the edges of the first porous substrate layer (423a), the first ion-selective polymer layer (421a), the second ion-selective polymer layer (421b), and the second porous substrate layer (423b). Additionally, the first separator and the second separator may use a folding method, which involves folding to join the edges, or a cap sealing method, which involves sealing the edges of the separator with a cap.

[0095] Although preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the specific embodiments described above. Various modifications are possible by those skilled in the art without departing from the essence of the invention as claimed in the patent claims, and such modifications should not be understood individually from the technical spirit or perspective of the present invention.

Claims

1. A first liquid electrode where the first half-reaction takes place; A second liquid electrode where a second half-reaction takes place; and A secondary battery comprising a plurality of separators arranged to overlap each other between the first liquid electrode and the second liquid electrode, with a space formed between them.

2. In Paragraph 1, The plurality of separators is a secondary battery that stores a portion of the first liquid electrode and / or the second liquid electrode in the space.

3. In Paragraph 1, Each of the above plurality of separators is a secondary battery comprising a polybenzimidazole (PBI)-based polymer.

4. In Paragraph 1, A secondary battery in which the active material of the first liquid electrode, which has passed through one of the plurality of separators after the charging reaction is completed at the first liquid electrode and the second liquid electrode, is oxidized in the space.

5. In Paragraph 1, A secondary battery in which the active material of the second liquid electrode that has passed through one of the plurality of separators after the charging reaction is completed at the first liquid electrode and the second liquid electrode is reduced in the space.

6. In Paragraph 1, A secondary battery in which, after the charging reaction is completed at the first liquid electrode and the second liquid electrode, the oxidation number of the active material existing in the space is between the oxidation number of the active material of the first liquid electrode and the oxidation number of the active material of the second liquid electrode.

7. In Paragraph 1, Each of the above plurality of separators is a secondary battery that is a polybenzimidazole-based ion-selective polymer.

8. In Paragraph 1, The above plurality of separation membranes are, First separator; and A secondary battery comprising a second separator arranged overlapping the first separator, wherein the space is formed between the first separator and the second separator.

9. In Paragraph 8, The above plurality of separation membranes are, A secondary battery further comprising a third separator arranged overlapping the second separator, wherein the space is formed between the second separator and the third separator.

10. In Paragraph 1, The above space is a secondary battery formed in plurality between the plurality of separators.

11. In Paragraph 10, The above plurality of spaces are arranged spaced apart on the plane formed by the separator, forming a secondary battery.

12. In Paragraph 10, The above plurality of spaces are arranged in a direction in which the above plurality of separators overlap, forming a secondary battery.

13. In Paragraph 1, Each of the above plurality of separation membranes is formed by coating an ion-selective polymer layer on one surface of a porous substrate layer, and A secondary battery in which the plurality of separators are arranged such that each of the ion-selective polymer layers faces each other.

14. The entire 1st house; A second collector positioned spaced apart from the first collector above; A plurality of separators disposed between the first current collector and the second current collector; A first liquid electrode disposed between the first current collector and the separator, wherein a first half-reaction occurs and the first liquid electrode is electrically connected to the first current collector; and It includes a second liquid electrode disposed between the second current collector and the separator, wherein a second half-reaction occurs and the second liquid electrode is electrically connected to the second current collector. The plurality of separators is a secondary battery that stores a portion of the first liquid electrode and / or the second liquid electrode.

15. The entire first house; A first liquid electrode in which a first half-reaction occurs and which is electrically connected to the first current collector; A first separator disposed spaced apart from the first current collector and forming a space in which the first liquid electrode is stored; The entire 2nd house; A second liquid electrode in which a second half-reaction occurs and which is electrically connected to the second current collector; It includes a second separator disposed spaced apart from the second current collector to form a space in which the second liquid electrode is stored, and A secondary battery in which the first separator and the second separator are arranged overlappingly and a space is formed between them.

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