Separation membrane complex and redox flow battery

Abstract

The present disclosure relates to a separation membrane complex having an anion exchange membrane and a cation exchange membrane coming in face-to-face contact with each other, and the cation exchange membrane and the anion exchange membrane each having two or more concavities and convexities which interlock with each other in a reverse phase.

Claims

1. A separation membrane complex having an anion exchange membrane and a cation exchange membrane coming in face-to-face contact with each other, the cation exchange membrane and the anion exchange membrane each having two or more concavities and convexities which interlock with each other in a reverse phase, wherein a height of the concavities and convexities of the anion exchange membrane is 20 μm to 80 μm, wherein a width of the concavities and convexities of the anion exchange membrane is 20 μm to 80 μm, wherein the distance between the concavities and convexities adjacent to each other in the anion exchange membrane is 20 μm to 80 μm.

2. The separation membrane complex of claim 1, wherein the separation membrane complex is used for a redox flow battery.

3. The separation membrane complex of claim 1, wherein the anion exchange membrane includes an anion exchange polymer in which one or more anion exchange functional groups selected from the group consisting of ammonium, phosphonium and sulfonium are substituted.

4. The separation membrane complex of claim 1, wherein the cation exchange membrane includes a cationic polymer in which one or more cation exchange functional groups selected from the group consisting of a sulfonic acid group, a carboxyl group and a phosphoric acid group are substituted.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a graph showing the results of evaluation of the charge and discharge performance of a unit cell including the separation membrane complex of Example 1 and Comparative Example 1.

(2) FIG. 2 is a schematic diagram of a unit cell for confirming the performance of the separation membrane complex of Example 1 and Comparative Example 1.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(3) Hereinafter, the present disclosure will be described in more detail with reference to examples. However, these Examples are presented only to illustrate the invention and the scope of the present disclosure is not limited thereto.

Example 1

(4) An anion exchange resin (trimethylammonium functionalized polysulfone) was spin-coated on a silica mold that had been subjected to a hydrophilic treatment through a process such as plasma at 3000 rpm for 60 seconds. It was dried at a temperature of 80° C. for 3 hours, and the silicon mold coated with the anion exchange resin was impregnated with deionized water to obtain an anion exchange resin membrane.

(5) At this time, in the anion exchange resin film, a plurality of concavities and convexities were formed on the substrate surface having a thickness of about 10 μm at a height of about 40 μm and a spacing of about 20 μm.

(6) Then, a 25 μm thick Nafion (Nafion D520, DuPont) was placed on the anion-exchange resin film on which the concavities and convexities were formed, and thermally pressed at a temperature of 130° C. under a pressure of 5 atm to prepare a separation membrane complex.

Comparative Example 1

(7) A 50 μm thick Nafion (Nafion 212, DuPont) separation membrane was used.

Experimental Example: Evaluation of Charge/Discharge Performance

(8) In order to confirm the performance of the separation membrane of Example 1 and Comparative Example 1, a unit cell was prepared as shown in FIG. 2. The unit cell is composed of a flow frame 50 for forming a flow path so that the electrolyte can move symmetrically to the separation membrane 60, an electrode 40 for moving electrons, and an end plate 30 that serves to maintain a unit cell shape and plays a role as a support. The electrolyte in the electrolyte container was supplied to the unit cell via a pump, and an electric current was applied through a charging/discharging device 70 so that charging and discharging were performed.

(9) As the electrolyte solution stored in the electrolyte container, a solution in which 1.5M VOSO.sub.4 was dissolved in 3M H.sub.2SO.sub.4 aqueous solution was used. The electrolyte used an anode and a cathode in an amount of 40 ml, respectively, and the electrolyte supplied from an electrolyte circulating pump was supplied at a rate of 40 ml/min. In addition, the anode electrolyte was used as a V(+4)/V(+5) redox couple, and the cathode electrolyte was used as a V(+2)/V(+3) redox couple.

(10) With respect to the unit cells prepared by the separation membranes of Example 1 and Comparative Example 1, one stripping after one charge/discharge process was set to 1 cycle, and the energy efficiency, voltage efficiency and charge efficiency were measured. The results are shown in Table 1 below. At this time, the voltage efficiency [VE, the calculation method is the average discharge voltage (V)/average charge voltage (V)] was measured by dividing the average charge voltage and the average discharge voltage, and the energy efficiency (EE, the calculation method is the charge output amount (Wh)/discharge output amount (Wh)) was measured by dividing the charge output amount and the discharge output amount.

(11) At this time, Wonatec product was used as a charge/discharge device, and the measurement was performed under the conditions of room temperature, total charge of the system of 1.6 Ah, charge/discharge voltage range of 0.8 to 1.6 Ah, charge of 80 mA/cm.sup.2, discharge of 80 mA/cm.sup.2, and voltage of less than 0.01V.

(12) TABLE-US-00001 TABLE 1 Unit: % Voltage Charge (28 cycle average) Energy efficiency efficiency efficiency Example 1 81.77 83.01 98.49 Comparative 69.77 78.15 89.39 Example 1

(13) As shown in Table 1 and FIG. 1, it was confirmed that the unit cell including the separation membrane of Example 1 was significantly superior in energy efficiency, voltage efficiency, and charge efficiency compared to the unit cell including the separation membrane of Comparative Example 1.

DESCRIPTION OF SYMBOLS

(14) 30: end plate 40: electrode 50: flow frame 60: separation membrane 70: charge/discharge device