KR102000659B1 - Preparation method for composite separator for redox flow batterry and composite separator for redox flow batterry - Google Patents

Abstract

The present invention relates to a method for preparing a porous polymeric resin film, comprising the steps of: applying a coating composition comprising at least one surface of a porous polymeric resin film having a weight average molecular weight of 1,000,000 to 10,000,000, And retaining the porous polymer resin film coated with the coating composition in a hydrogen peroxide solution, a sulfuric acid solution, or deionized water for 10 minutes or more.

Description

TECHNICAL FIELD [0001] The present invention relates to a composite separator for a redox flow cell, and a composite separator for a redox flow battery. BACKGROUND ART [0002]

The present invention relates to a process for producing a composite separator for redox flow cells and a composite separator for redox flow cells.

Existing power generation systems, such as thermal power generation using nuclear fossil fuels and large-scale greenhouse gas and environmental pollution problems, and nuclear power generation, which have the problems of stability of the facility itself or waste disposal problems, have various limitations and are more environmentally friendly and highly efficient Research on the development of energy and the development of power supply system using it has been greatly increased.

Particularly, the power storage technology makes it possible to utilize renewable energy which is greatly influenced by external conditions in a wider and wider range, and the efficiency of power utilization can be further increased. And research and development have been increasing.

The redox flow cell is an oxidation / reduction cell that can convert the chemical energy of the active material directly into electrical energy. It stores renewable energy with high output fluctuation depending on the external environment such as sunlight and wind power and converts it into high quality power Energy storage system. Specifically, in the redox flow cell, the electrolyte containing the active material causing the oxidation / reduction reaction circulates between the opposite electrode and the storage tank, and charging / discharging proceeds.

The redox flow cell basically includes a tank storing different active materials in oxidation states, a pump circulating the active material during charging / discharging, and a unit cell divided into a separation membrane. The unit cell includes an electrode, an electrolyte, and a separation membrane do.

The separator of the redox flow cell is a core material that generates current flow through the movement of ions generated in response to the anode and cathode electrolyte during charge discharge. Current redox flow cells generally use lead-acid battery separators or fuel cell ion-exchange membranes, depending on the type of battery, but these prior separator membranes cause crossover of ions between the positive and negative electrode electrolytes and degrade the energy efficiency of the cells It is difficult to sufficiently secure the life of the battery because the resistance to the electrolytic solution used is not sufficient and the price competitiveness is also limited.

The present invention relates to a composite separator for a redox flow cell having improved ion exchange capacity and hydrophilicity and capable of effectively reducing the crossover of the charged active material in the electrolyte solution and the degradation of the energy density of the battery and having excellent durability and chemical resistance Method.

The present invention also provides a composite material for a redox flow cell having improved ion exchange ability and hydrophilicity and capable of effectively reducing crossover of the active material packed in the electrolyte solution and lowering of the energy density of the battery and having excellent durability and chemical resistance To provide a separation membrane.

The present invention also provides a redox flow cell comprising the composite separator.

The present invention relates to a method for producing a porous polymeric resin film, comprising the steps of: applying a coating composition containing a fluorine resin or a hydrocarbon resin having at least one cation exchange functional group substituted on at least one surface thereof; And retaining the porous polymer resin film coated with the coating composition in a hydrogen peroxide solution, a sulfuric acid solution, or deionized water.

The present invention also relates to a porous polymeric resin film; And a coating layer formed on at least one surface of the porous polymeric resin film and comprising a fluorine resin substituted with at least one cation exchange functional group.

The present invention also provides a redox flow cell comprising the composite separator.

Hereinafter, a method of manufacturing a composite separator for a redox flow cell according to a specific embodiment of the present invention will be described in detail.

According to an embodiment of the present invention, there is provided a method of manufacturing a porous polymeric resin film, comprising: coating a porous polymeric resin film with a coating composition comprising a fluorine resin or a hydrocarbon resin having at least one cation exchange functional group substituted on at least one surface thereof; And a step of retaining the porous polymer resin film coated with the coating composition in a hydrogen peroxide solution, a sulfuric acid solution or deionized water, and a method for producing a composite separator membrane for a redox flow battery.

The present inventors have found that when a coating composition containing a fluorine resin having one or more cation exchange functional groups substituted on one or both surfaces of a porous polymer resin film is applied and the porous polymer resin film coated with the coating composition is immersed in a hydrogen peroxide solution, The composite membrane for a redox flow battery was prepared through a step of staying for 10 minutes or longer. The composite membrane for a redox flow battery was characterized in that the surface properties, electrical characteristics, and characteristics of the coating layer were used to reduce crossover of the charged active material, It has been confirmed through experiments that the effect of improving the migration speed of cation or anion, hydrophilicity and conductivity is improved and the invention is completed.

Particularly, the coating layer of the composite separator for a redox flow battery includes a polymer having at least one cation exchange functional group substituted thereon, thereby facilitating the balance between the cathode portion and the anode portion of the redox flow cell fractionated by the composite separator.

Accordingly, the composite separator for redox flow battery can have improved ion exchange capacity, can prevent the crossover of the charged active material and the energy density of the battery, and the polymer resin having high durability and chemical resistance It is easy to secure the lifetime of the battery.

The coating layer formed on at least one surface of the porous polymeric resin film and including a polymer having one or more cation exchange functional groups substituted therein may have a thickness of 1 to 300 탆.

On the other hand, one or more cation exchange functional groups of sulfonic acid group, carboxylic acid group, or phosphoric acid group may be substituted in the fluorine-based or hydrocarbon-based resin in which the cation exchange functional group is substituted by one or more.

Specific examples of the fluororesin include fluororesins such as polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP) , Ethylene-tetrafluoroethylene copolymer resin (ETFE), tetrafluoroethylene-chlorotrifluoroethylene copolymer (TFE / CTFE) and ethylene-chlorotrifluoroethylene resin (ECTFE) And the like. Further, as commercially available products of the fluorine-based resin substituted at least said cation-exchange functional groups. 1 and the like can be mentioned ^{Nafion ® (Dupont), Equivion ®} (Solvay), Flemion TM (AGC chemicals company), Aciplex TM (Asahi Kasei) .

Specific examples of such a hydrocarbon resin include at least one polymer selected from the group consisting of polyethylene, polysulfone, polyphenylene oxide, polyphenylene, poly-ether-ether-ketone and polyvinyl chloride.

The weight average molecular weight of the fluorine-based resin or the hydrocarbon-based resin having at least one cation exchange functional group substituted therein is not particularly limited, but may have a weight average molecular weight of, for example, 10,000 to 300,000. The weight average molecular weight means the weight average molecular weight in terms of polystyrene measured by GPC method.

The cation exchange function (-) enhances the electrophilic electrolyte property on the surface of the coating layer. The cation exchange functional group (-) improves the voltage efficiency by enabling rapid ion transfer through attraction with zinc ions (+) in the electrolytic solution, Can also act as a crossover suppressor of an active material such as bromine (Br _n ^- ), thereby improving the charge efficiency.

The cation exchange functional group may include a sulfonic acid group, a carboxylic acid group, or a phosphoric acid group. Due to the presence of such a cation exchange functional group, the electrolyte affinity of the surface of the composite separator membrane for the redox flow battery of the above embodiment is increased, and ion exchange in the electrolyte is accelerated through interaction between the zinc ion and the cation exchange functional group in the electrolyte of the battery, And the resistance between the redox flow cell composite separator membrane can be reduced to improve the voltage efficiency.

The coating composition containing the fluorine resin or the hydrocarbon resin having at least one cation exchange functional group substituted therein may contain 1 to 30% by weight of the fluorine resin or the hydrocarbon resin substituted by one or more of the cation exchange functional groups.

The coating composition may contain an organic solvent, a water-soluble solvent or a mixed solvent thereof in addition to the fluorine-based resin or the hydrocarbon-based resin in which the cation exchange functional group is substituted by one or more of the cation exchange functional groups. More specifically, The fluorinated resin or the hydrocarbon resin having at least one substituent may be a mixed solvent of isopropanol and deionized water, a mixed solvent of N-methylpyrrolidone, dimethylacetamide, dimethylformamide, dimethylsulfoxide, or ethylene glycol May be dispersed or dissolved.

The thickness of the coating composition containing the fluorocarbon resin or the hydrocarbon resin having the cation exchange functional groups substituted on the porous polymeric resin film may be varied depending on the specific application or purpose of the final separator for redox flow battery , For example, the coating composition may be coated on the porous polymeric resin film to a thickness of 0.1 to 1,000 mu m.

On the other hand, the shape of the inside of the separation membrane is maintained through a step of retaining the porous polymer resin film coated with the coating composition in a hydrogen peroxide solution, a sulfuric acid solution or deionized water for 10 minutes or more, or 0.5 hours or more, or 1 hour or more, Thereby providing a separator that minimizes cross-mixing of the active material that causes the internal resistance of the battery and the self-discharge.

Specifically, the step of allowing the porous polymer resin film coated with the coating composition to remain in the hydrogen peroxide solution, the sulfuric acid solution, or the deionized water for 10 minutes or more may be performed by a method comprising: applying the porous polymer resin film coated with the coating composition to a hydrogen peroxide solution having a temperature of 30 to 100 ° C, Sulfuric acid solution or deionized water for 0.5 to 80 hours.

Although the temperature of the hydrogen peroxide solution, the sulfuric acid solution or the deionized water in which the porous polymer resin film coated with the coating composition is present is not limited to a great extent, if the temperature of the hydrogen peroxide solution, the sulfuric acid solution or the deionized water is too low, there is no change in the shape of the interior of the separator due to insufficient swelling or the like, or the cross-mixing of the active materials can not be prevented.

In addition, although the time for residence of the porous polymer resin film coated with the coating composition in the hydrogen peroxide solution, the sulfuric acid solution or the deionized water is not limited, the presence of impurities in the membrane, insufficient ion cluster swelling There is no change in the shape of the inside of the separator or the cross-mixing of the active material can not be prevented, so that the expected effect may not be achieved.

The hydrogen peroxide solution and the sulfuric acid solution can also serve to remove impurities from the inside of the membrane. The hydrogen peroxide solution may have a concentration of 1 to 10% by weight. The sulfuric acid solution may have a concentration of 1M to 3M.

The deionized water may serve to swell ion clusters in the separation membrane.

Meanwhile, the porous polymer resin membrane serves as a base material of the composite separator membrane for the redox flow cell, and the porous polymer resin membrane may be made of a polymer resin known to be used as a separation membrane of a chemical flow battery.

The porous polymer resin film may include pores having a maximum diameter of 1 nm to 10 mu m, or 10 nm to 1 mu m. The shape of the pores is not limited to a specific one. The cross-sectional shape of the porous polymeric resin film may be circular, elliptical, polygonal with three or more angles, It may be a polygon of 6 or more.

The porous polymer resin membrane may include a polymer resin having a weight average molecular weight of 100,000 to 10,000,000. If the weight average molecular weight of the polymer resin of the porous polymeric resin film is too small, it may be difficult to sufficiently ensure the durability and chemical resistance of the separable membrane for the redox-flowable battery. In addition, if the weight average molecular weight of the polymer resin of the porous polymeric resin film is too large, the distribution of the pores formed on the separation membrane and the size of the pores themselves may become uneven.

Specifically, the porous polymeric resin film may be formed of a high molecular weight polyethylene (HDPE), a low density polyethylene (LDPE), a linear low density polyethylene (LLDPE), an ethylene vinyl acetate copolymer (EVA), a polypropylene (PP), a polycarbonate (PAN) and polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyvinylchloride, polyvinylidene chloride, polyethersulfone, polysulfone ), Polyetherketone, poly-ether-ether-ketone, polyethylene ether nitrile, or a mixture of two or more thereof.

Polydopamine may be bonded to the surface of the porous polymeric resin film. Such polypodamine may be partially bonded to the surface of the porous polymeric resin film, or a polymer resin layer containing polypodamine may be formed on the surface of the porous polymeric resin film. The polypodamine may be bonded to the surface of the porous polymer resin film by forming a polymer resin layer to a thickness of 1 nm to 100 nm.

The thickness of the porous polymeric resin film may be determined according to the shape, size, and characteristics of the redox-flow battery to be applied, and may be, for example, 10 to 600 탆.

On the other hand, the porous polymer resin film may further include 0.5 to 75% by weight of inorganic particles dispersed therein. These inorganic particles may include at least one member selected from the group consisting of silica, modified silica, organosilane compound and titanium compound.

Examples of the modified silica include at least one compound selected from the group consisting of compounds represented by Chemical Formulas 1 to 4 below.

[Chemical Formula 1]

Wherein Y ₁ is a straight or branched alkylene group having 1 to 10 carbon atoms in which at least one of fluorine is substituted or unsubstituted, X ₁ is a halogen group, and R ₁ , R ₂ and R ₃ are each a carbon number of 1 Lt; / RTI > is a straight or branched chain alkyl group of 1 to 4 carbon atoms.

(2)

Y ₂ and Y ₃ are straight or branched alkylene groups having 1 to 10 carbon atoms in which at least one of fluorine is substituted or unsubstituted and R ₄ , R ₅ , R ₆ and R ₇ are each a straight or branched alkylene group having 1 to 10 carbon atoms, 4 < / RTI > linear or branched alkyl group.

(3)

Y ₄ and Y ₅ are straight or branched alkylene groups of 1 to 10 carbon atoms in which at least one of fluorine is substituted or unsubstituted and R ₈ and R ₉ are each a straight or branched chain having 1 to 4 carbon atoms Lt; / RTI >

 [Chemical Formula 4]

In Formula 4, Y < ₅ > is a linear or branched alkylene group having 1 to 10 carbon atoms.

The separator for a redox flow cell containing specific modified silica particles dispersed in the porous resin film can improve the migration rate and conductivity of cations and anions due to the terminal functional groups contained in the compounds represented by Chemical Formulas 1 to 4 have.

The modified silica may have a number average particle diameter of 1 nm to 600 nm. If the number average particle size of the modified silica particles is too small, the ion crossover phenomenon due to the increase of the water content of the separator for the redox flow battery can be intensified. If the number average particle size of the modified silica particles is too large, the dispersibility of the modified silica particles may be deteriorated and the ion conductivity of the separator for the redox flow battery may be lowered, which is technically disadvantageous.

Polydopamine may be bonded to the surface of the modified silica. Such polypodamine may be partially bonded to the surface of the modified silica, or may form a polymer resin layer containing polypodamine. The above-mentioned polypodamine can be bonded to the surface of the modified silica with a thickness of 1 nm to 100 nm to form a polymer resin layer.

Specific examples of the organosilane compound include tetraethyl orthosilicate (TEOS), 3-glycidyloxypropyltrimethoxysilane (GOTMS), monophenyl triethoxysilane (MPh), and polyethoxysilane (PEOS).

Specific examples of the titanium-based compound include titanium dioxide (TiO 2), titanium (II) oxide (TiO 2), and titanium (III) oxide (Ti 2 O 3).

As described above, the composite membrane for a redox-flow battery provided according to the above-described method is characterized in that the surface properties, electrical characteristics, and characteristics of each component of the coating layer reduce crossover of the charged active material, Speed improvement, hydrophilicity and conductivity improvement. Particularly, the coating layer of the composite separator for a redox flow battery includes a polymer having at least one cation exchange functional group substituted thereon, thereby facilitating the balance between the cathode portion and the anode portion of the redox flow cell fractionated by the composite separator.

Accordingly, the composite separator for a redox flow battery can have a more improved ion exchange capacity, can prevent a crossover of a charged active material between the anode and the anode electrolyte and a decrease in the energy density of the battery, By using a polymer resin having chemical properties, it is easy to secure the lifetime of the battery.

The coating layer formed on at least one surface of the porous polymeric resin film and including a polymer having one or more cation exchange functional groups substituted therein may have a thickness of 1 to 300 탆.

According to another embodiment of the present invention, there is provided a porous polymeric resin film; And a coating layer formed on at least one surface of the porous polymeric resin film and including a fluorine resin having one or more cation exchange functional groups substituted thereon, and a composite separator for a redox flow cell.

The inventors of the present invention have found that the composite membrane for a redox flow cell produced by forming a coating layer containing a fluorine-based or hydrocarbon-based resin having one or more cation exchange functional groups substituted on one or both surfaces of a porous polymeric resin film, It has been confirmed through experiments that the crossover of the charged active material is improved, the migration speed of the cation or the anion is increased, the hydrophilicity and the conductivity are improved owing to the characteristics of the respective components.

Particularly, the coating layer of the composite separator for a redox flow battery includes a polymer having at least one cation exchange functional group substituted thereon, thereby facilitating the balance between the cathode portion and the anode portion of the redox flow cell fractionated by the composite separator.

Accordingly, the composite separator for a redox flow battery can have a more improved ion exchange capacity, can prevent a crossover of a charged active material between the anode and the anode electrolyte and a decrease in the energy density of the battery, By using a polymer resin having chemical properties, it is easy to secure the lifetime of the battery.

The coating layer formed on at least one surface of the porous polymeric resin film and including a polymer having one or more cation exchange functional groups substituted therein may have a thickness of 1 to 300 탆.

One or more cation exchange functional groups including a sulfonic acid may be substituted for the fluorine-based or hydrocarbon-based resin in which the cation exchange functional group is substituted by one or more.

Specific examples of the fluororesin include fluororesins such as polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP) , Ethylene-tetrafluoroethylene copolymer resin (ETFE), tetrafluoroethylene-chlorotrifluoroethylene copolymer (TFE / CTFE) and ethylene-chlorotrifluoroethylene resin (ECTFE) And the like. Examples of commercialized products of the fluorine-based resin having one or more cation exchange functional groups include Nafion (Dupont), Equivion (Solvay), Flemion (AGC chemicals company) and Aciplex (Asahi Kasei).

Specific examples of such a hydrocarbon resin include at least one polymer selected from the group consisting of polyethylene, polysulfone, polyphenylene oxide, polyphenylene, poly-ether-ether-ketone and polyvinyl chloride.

The weight average molecular weight of the fluorine-containing or hydrocarbon-based resin having one or more cation exchange functional groups substituted therein is not particularly limited, but may have a weight average molecular weight of 10,000 to 300,000, for example. The weight average molecular weight means the weight average molecular weight in terms of polystyrene measured by GPC method.

The porous polymer resin membrane may include a polymer resin having a weight average molecular weight of 100,000 to 10,000,000. If the weight average molecular weight of the porous polymeric resin film is too small, it may be difficult to secure sufficient durability and chemical resistance of the separable membrane for redox flow battery. Also, if the weight average molecular weight of the porous polymeric resin film is too large, the distribution of the pores formed on the separation membrane and the size of the pores themselves may become uneven.

The porous polymer resin film may include pores having a maximum diameter of 1 nm to 1 占 퐉 and may have a thickness of 1 占 퐉 to 600 占 퐉.

The porous polymeric resin film may further include 0.5 to 75% by weight of inorganic particles dispersed therein.

The inorganic particles may include at least one member selected from the group consisting of silica, modified silica, organosilane compound, and titanium compound.

Other than the above-mentioned contents, the contents of the composite separator for a redox-flow battery include those described in the production method of a composite separator for a redox-flow battery according to the embodiment described above.

According to another embodiment of the present invention, there is provided a unit cell including the composite separator and the electrode. A tank in which different active materials are stored in oxidation states; And a pump for circulating the active material between the unit cell and the tank at the time of charging and discharging.

The redox flow cell may include a module including at least one unit cell.

The redox flow cell may use a V ⁴⁺ / V ⁵⁺ couple as a positive electrode electrolyte and a V ²⁺ / V ³⁺ couple as a negative electrode electrolyte.

Also, the redox flow cell may use a bromine redox couple as a positive electrode electrolyte and a sulfide redox couple as a negative electrode electrolyte.

In addition, the redox flow cell may use a vanadium redox couple as a positive electrode electrolyte and a bromine redox couple as a negative electrode electrolyte.

Also, the redox flow battery may use a zinc-bromine redox couple as a cathode and a cathode electrolyte.

The system of the redox flow cell may further include a flow frame.

The flow frame not only serves as a passage for the electrolyte but also provides an even distribution of the electrolyte between the electrode and the separator so that the electrochemical reaction of the actual cell can be performed well.

The flow frame may have a thickness of 0.1 mm to 10.0 mm and may be made of a polymer such as polyethylene, polypropylene, or polyvinyl chloride.

According to the present invention, it is possible to effectively reduce crossover of the charged active material between the positive electrode and the negative electrode electrolyte in the electrolyte solution and decrease in the energy density of the battery, which has improved ion exchange ability and hydrophilicity and is excellent in durability and chemical resistance. There is provided a method for producing a composite separator for a toxic flow cell and a composite separator for a redox flow battery manufactured from the same, and a redox flow cell including the composite separator is also provided.

1 is a SEM photograph of the surface of a composite separator for a redox flow cell manufactured in Comparative Example 1 (above) and Example 1 (below).
FIG. 2 is a SEM photograph of a cross section of a composite separator for a redox flow cell prepared in Example 1 including a coating layer.
3 shows the bromine permeability of the composite separator for the redox flow cell of Example 2 and Comparative Example 1, respectively.
4 is a graph showing charge voltages (solid lines) and discharge voltages (dotted lines) measured in the charge and discharge tests of the single cells including the composite separator for redox flow battery of Example 3 and Comparative Example 2, respectively.
FIG. 5 shows charge voltages (solid lines) and discharge voltages (dotted lines) measured in the charge and discharge tests of the single cells including the composite separator for the redox flow battery of Example 2 and Comparative Example 1, respectively.
6 schematically shows the structure of the single cell produced in the Experimental Example.

The invention will be described in more detail in the following examples. However, the following examples are illustrative of the present invention, and the present invention is not limited by the following examples.

[ Example  And Comparative Example : Redox  Preparation of composite separator for flow cell]

Example 1

DE521 (Nafion 5 wt% in IPA / water) from DuPont was dried in an oven at 80 ° C to obtain a solidified Nafion resin. Then, the resin was dissolved in N-methylpyrrolidone solvent to prepare a 10 wt% solution. The solution was coated on a Asahi SF-601 (polyethylene porous separator containing silica: weight average molecular weight: about 700,000 g / mol, thickness about 600 μm) with a wet thickness of 75 μm. The coated separator was dried in an oven at 80 캜 for 6 hours. Then, the coated membrane obtained after drying was impregnated in DI water at 80 DEG C for 6 hours.

Example 2

(Polyethylene porous separator containing silica: weight average molecular weight: about 700,000 g / mol, thickness about 600 탆) of Asahi under the conditions of a wet thickness of 75 탆, Coated on one side. The coated separator was dried at a temperature of 25 DEG C for 10 hours, coated on the other surface in the same manner, and dried in the same manner for 10 hours.

Then, the coated separator was dried in an oven at 50 ° C for 1 hour. Then, the coated membrane obtained after drying was impregnated in DI water at 80 DEG C for 6 hours.

Example 3

DE521 (Nafion 5 wt% in IPA / water) from DuPont was dried in an oven at 80 ° C to obtain a solidified Nafion resin. Then, the resin was dissolved in N-methylpyrrolidone solvent to prepare a 10 wt% solution. The solution was coated on one side of a polyethylene porous separator (weight average molecular weight: about 6,000,000 g / mol, thickness about 175 μm) containing silica with a wet thickness of 75 μm.

The coated separator was dried in an oven at 80 캜 for 6 hours. Then, the coated membrane obtained after drying was impregnated in DI water at 80 DEG C for 6 hours.

Comparative Example 1

SF-601 (silica-containing polyethylene porous separator) was used as a separator without any additional treatment.

Comparative Example 2

A polyethylene porous separator containing silica (weight average molecular weight: about 6,000,000 g / mol, thickness: about 175 μm) was used as a separator without any additional treatment.

< Experimental Example : Redox For flow cell  Measurement of Physical Properties of Membrane>

1. Surface analysis method of coating layer

In order to confirm the surface uniformity of the membranes of Examples and Comparative Examples and the thickness of the coating layer, the surface and cross-sections of the membranes were analyzed by FE-SEM (Field Emission Scanning Electron Microscope, HITACHI SU8220).

 Surface observation with FE-SEM As shown in Fig. 1, the coating membrane of Example 1 (below) showed a comparatively dense surface structure with the membrane of Comparative Example 1 (above).

As shown in FIG. 2, it was confirmed by FE-SEM that a coating layer free of release was formed on the base film on the surface of the coating separator of Example 1.

2. Br ₂  Permeability measurement

The concentration of Br ₂ passing through the separation membrane of the separation membranes of Examples and Comparative Examples was measured with time.

Specifically, by placing the membrane between two containers of Diffusion cell, a container is deionized water fills in (DI water) other container _{ZnCl 2 (0.55 M), MEP} -Br (0.80 M), Br 2 (2.285 M) Respectively. The Br ₂ concentration of the sample obtained at a given time from the vessel filled with DI water was measured and the Br ₂ permeability of the membrane was calculated using the following equation:

D: = membrane thickness, C _A : = Br ₂ concentration in the high concentration solution vessel, d: = thickness of the membrane, A: = exposure to the solution, P = membrane permeability, V _B = The width of the membrane surface

As can be seen in FIG. 3, the Br ₂ permeability analysis showed that the coating membrane of Example 2 had reduced Br ₂ permeability as compared to the membrane of Comparative Example 1.

3. Zinc - Bromine Redox  flow Of a single cell  Internal resistance measurement

In order to evaluate the suitability of Zn-Br CFB in the separator prepared in each of the comparative example and the example, it was assembled into a single cell, and then measured with a DC resistance meter after 3 hours of circulation of electrolyte with 0% state of charge (SOC). The unit cell was stuck to the same structure as shown in Fig.

As a result of measuring the internal resistance, the coating separator (223 m?) Of Example 2 was lower than that of the separator (273 m?) Of Comparative Example 1.

4. Charging and discharging  Measure efficiency

The single cell prepared according to FIG. 6 was charged and discharged under the conditions of room temperature, 2.98 Ah of charge, 20 mA / cm 2 of charge and 20 mA / cm 2 of discharge under the condition of charge and discharge. 1 cycle.

* Energy Efficiency (E.E.) = discharge energy / charge energy

* Columbic Efficiency (C.E.) = discharge charge (Ah) / charge charge (Ah)

* Voltage Efficiency (V.E.) = Energy Efficiency / Voltage Efficiency

As shown in the following Table 1, the coating separator of Example 2 had a lower value than the separator of Comparative Example 1 as a result of internal resistance measurement, which resulted in improved voltage efficiency and energy efficiency as a result of charge / discharge test.

Sample Internal resistance
(mΩ) efficiency (%) energy Voltage Charge quantity Comparative Example 1 273 73.3 81.1 90.4 Example 2 223 77.7 84.0 92.6

In addition, as shown in FIG. 5, the coating separator of Example 2 exhibited a higher discharge voltage and an increased discharge charge as compared with the separator of Comparative Example 1. As shown in FIG. 4, the coating separator of Example 3 exhibited a higher discharge voltage and an increased discharge charge as compared with the separator of Comparative Example 2 as a result of the charge-discharge test. As a result of the above two experiments, it was confirmed that the effect of the coating is increased as the thickness of the porous polymer resin film is small and the porosity is high.

1: End plate
2: graphite collector
3: Flow frame
4: Spacer
5: Membrane
6: electrode active layer
7: Carbon felt

Claims (17)

Coating a porous polymer resin film with a coating composition containing a fluorine resin or a hydrocarbon resin having at least one cation exchange functional group substituted on at least one surface thereof; And
Treating the porous polymer resin film coated with the coating composition with a hydrogen peroxide solution, a sulfuric acid solution or deionized water,
Wherein the coating composition comprises 1 to 30% by weight of a fluorine-based resin or a hydrocarbon-based resin having one or more cation exchange functional groups substituted thereon,
Wherein the coating composition is coated on the porous polymeric resin film to a thickness of 0.1 to 1,000 占 퐉,
Wherein the step of treating the porous polymer resin film coated with the coating composition with a hydrogen peroxide solution, a sulfuric acid solution or deionized water is performed by immersing for 10 minutes or more,
(Method for producing composite separator for redox flow battery).
The method according to claim 1,
Wherein the porous polymer resin membrane comprises a polymer resin having a weight average molecular weight of 100,000 to 10,000,000.
delete The method according to claim 1,
Wherein the cation exchange functional group is a sulfonic acid group, a carboxylic acid group or a phosphoric acid group, (Method for producing composite separator for redox flow battery).
The method according to claim 1,
The fluororesin may be at least one selected from the group consisting of polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer At least one polymer selected from the group consisting of polymer resin (ETFE), tetrafluoroethylene-chlorotrifluoroethylene copolymer (TFE / CTFE) and ethylene-chlorotrifluoroethylene resin (ECTFE)
Wherein the hydrocarbon resin comprises at least one polymer selected from the group consisting of polyethylene, polysulfone, polyphenylene oxide, polyphenylene, poly-ether-ether-ketone and polyvinyl fluoride, &Lt; / RTI &gt;
delete The method according to claim 1,
Wherein the immersion is carried out by allowing the porous polymer resin film coated with the coating composition to stagnate in a hydrogen peroxide solution, sulfuric acid solution or deionized water having a temperature of 30 to 100 DEG C for 0.5 to 80 hours, .
The method according to claim 1,
The hydrogen peroxide solution has a concentration of 1 to 10% by weight,
Wherein the sulfuric acid solution has a concentration of 1M to 3M.
The method according to claim 1,
Wherein the porous polymeric resin film contains pores having a maximum diameter of 1 nm to 1 占 퐉 and has a thickness of 10 占 퐉 to 600 占 퐉.
The method according to claim 1,
Wherein the porous polymeric resin film further comprises 0.5 to 75% by weight of inorganic particles dispersed therein, based on the total weight of the porous polymeric resin film.
11. The method of claim 10,
Wherein the inorganic particles comprise at least one member selected from the group consisting of silica, modified silica, and titanium compounds.
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