KR20190106552A - Electrode of secondary battery and secondary battery comprising the same - Google Patents

Abstract

The present invention relates to an electrode for a secondary battery, capable of increasing the capacity and efficiency of charging/discharging, and a secondary battery including the same. The electrode for a secondary battery of the present invention comprises: a bipolar plate; a porous carbon block layer provided in a partial region of one surface of the bipolar plate; and a carbon felt layer provided in a region where the porous carbon block layer is not provided on one surface of the bipolar plate.

Description

Electrode for Secondary Battery and Secondary Battery Comprising the Same {ELECTRODE OF SECONDARY BATTERY AND SECONDARY BATTERY COMPRISING THE SAME}

The present specification relates to a secondary battery electrode and a secondary battery including the same.

Vanadium-redox flow battery (V-RFB) is a battery that attracts attention as an energy storage system (ESS), and has excellent long-term cycle stability, durability, and stability. However, vanadium redox flow battery has a disadvantage that the volume or weight is relatively large in order to implement the same amount of energy because of low energy density.

The electrode of the existing redox flow battery uses carbon felt, which has the advantage of having a large electrode active area and a fast transfer rate, but the electrolyte is evenly spread on the carbon felt electrode and participates in the reaction. Problems occur with pressure drop and delivery of constant concentration of electrolyte.

As a way to improve this, a flow path is formed in a bipolar plate, and a carbon paper electrode used in a fuel cell instead of carbon felt is used to reduce pressure buildup and maintain a mass transfer rate. Although the result of this report is reported, this method has a limited problem of using carbon paper, and when the carbon felt is used, the flow formed on the bipolar plate is blocked by the carbon felt and the flow is offset. have. For this reason, there is a problem that a carbon felt electrode having a large electrode active area cannot be utilized.

Korean Patent Application Publication No. 10-2016-0148935

The present specification is to provide a secondary battery electrode and a secondary battery comprising the same.

One embodiment of the present specification is a bipolar plate;

A porous carbon block layer provided on a portion of one surface of the bipolar plate; And

It provides a secondary battery electrode comprising a carbon felt layer provided in a region of the bipolar plate is not provided with a porous carbon block layer.

Another embodiment of the present specification provides a secondary battery including the secondary battery electrode.

According to an electrode for a secondary battery according to an exemplary embodiment of the present disclosure, by including a porous carbon block layer and a carbon felt layer on one surface of a bipolar plate, it is possible to efficiently induce the flow of the electrolyte in accordance with the flow rate of the electrolyte, thereby improving performance have.

When the electrode for a secondary battery according to the present disclosure is applied to the secondary battery, it is possible to increase the charge / discharge capacity and efficiency by increasing the electrochemical reaction opportunities between the electrolyte.

In the secondary battery electrode according to the present disclosure, when the electrode is applied to the secondary battery, the overvoltage may be lowered to lower the resistance value per unit area.

1 shows an electrode according to Example 1;
FIG. 2 illustrates a cross section in the AA ′ direction of the electrode of FIG. 1.
Figure 3 illustrates a cross-section in the direction perpendicular to the thickness direction of the electrode for secondary batteries of the electrode according to one embodiment of the present specification.
4 shows an electrode configuration in a battery according to Example 2. FIG.
5 and 6 are schematic views showing the structure of a redox flow battery according to an exemplary embodiment of the present specification.

Hereinafter, this specification is demonstrated in detail.

One embodiment of the present specification is a bipolar plate;

A porous carbon block layer provided on a portion of one surface of the bipolar plate; And

It provides a secondary battery electrode comprising a carbon felt layer provided in a region of the bipolar plate is not provided with a porous carbon block layer.

In one embodiment of the present specification, the carbon felt layer and the porous carbon block layer may function as an electrode.

In one embodiment of the present specification, the secondary battery electrode has the above-described structure, it is possible to effectively control the flow of the electrolyte.

In secondary batteries, especially redox flow batteries, the flow of electrolyte is very important. The electrolyte that has traveled through the electrolyte pump is transferred to the bipolar plate, which then contacts the electrode layer causing redox. At this time, if the flow rate characteristics of the electrolyte is not uniform, the difference in speed in the electrode layer, or overvoltage due to the portion that does not react. When an overvoltage occurs, the temperature inside the stack rises, and precipitation may occur when vanadium is used as an electrolyte.

In particular, when charging / discharging at high power conditions or increasing the size of the battery, the electrolyte is accompanied by a high flow rate, so that a high differential pressure may be generated between the electrolyte inlet and the electrolyte outlet, thereby resulting in enormous energy loss.

Therefore, the secondary battery may have a performance and lifespan determined by the flow rate characteristics of the electrolyte, and the present invention is intended to improve such flow rate characteristics. In particular, by reducing the internal pressure difference, it is intended to prevent energy loss from occurring and to stably control the flow rate of the electrolyte passing through the electrode.

Electrode for secondary battery according to the present specification is a porous carbon block layer provided in a portion of one surface of the bipolar plate; And a carbon felt layer provided in a region in which one surface of the bipolar plate is not provided with the porous carbon block layer. Here, the carbon block layer and the carbon felt layer correspond to the electrode layer. That is, the flow rate characteristic of the electrolyte solution mentioned above is controlled by introducing the electrode layer from which a characteristic differs in a single layer.

This is different from the electrode layer of a single layer structure composed of only one conventional material. In the case of the electrode layer having a single layer structure composed of only one material, it is not possible to effectively suppress the increase in the pressure difference between the electrolyte inlet and the electrolyte outlet. However, according to the electrode for a secondary battery according to one embodiment of the present specification, by introducing a carbon block layer and a carbon felt layer simultaneously in one single layer structure, it is possible to effectively suppress the increase in the pressure difference between the electrolyte inlet and the electrolyte outlet.

In the present specification, the porous carbon block refers to a spherical phenolic resin having a predetermined diameter blocked and carbonized at high temperature to be shaped as an electrode.

In the present specification, the bipolar plate is a configuration that can serve as a separation between the positive and negative electrodes and the electrolyte and a unit cell in a secondary battery or fuel cell configuration. The bipolar plate may be electrically connected to the porous carbon block layer or the carbon felt layer used as an electrode, and the unit cells may be electrically connected in series to increase the stack voltage.

In the present specification, the porous carbon block layer means a single layer or a multilayer structure including a carbon block. The porous carbon block layer is meant to include two or more pores.

In the present specification, when the flow battery is fastened, the thickness change of the carbon block is 10% or less, specifically 2% or less, and more specifically, may hardly change. In this case, when the flow battery cell to which the carbon block is applied is fastened, the carbon block hardly shrinks, so that even when the battery cell is fastened, the porosity of the carbon block may be maintained. Here, the change in porosity means the difference between the porosity before pressurization and the porosity after pressurization.

The carbon block may be filled with a composition comprising a spherical phenol resin and a binder in a block-type mold, and then compressed and carbonized to prepare a porous carbon block.

The carbon block is made of a spherical phenolic resin and filled with a composition containing the spherical phenolic resin and a liquid polyphenol in a block-type mold and compressed and then dried, degreasing, sintering and high-purification process of porous carbon Blocks can be produced.

In this case, the spherical phenol resin is a polymer, and the phenol resin is a resin obtained from phenols (phenol, cresol, xylenol, resorcinol) and aldehydes (formaldehyde, acetaldehyde, furfural) and their modified resins. It means the thermosetting resin containing.

The liquid polyphenol is a relatively low molecular weight liquid at room temperature and may serve as a binder resin connecting the spherical phenolic resin.

In this case, the spherical phenol resin particles used may be spherical poly resin particles having an average diameter of 100 ㎛ to 800 ㎛.

The carbon block has a compressive strength of 20 MPa or more, specifically 25 MPa or more. In this case, the carbon block hardly shrinks when the flow battery cell to which the carbon block is applied is fastened, so that the porosity of the carbon block in the battery cell is also manufactured. Can be maintained. In this case, the higher the compressive strength is, the better the higher the compressive strength is. In this case, the compressive strength means a value measured by the test analysis method specified in KS L 1601: 2006.

The sintered density of the carbon block is at least 0.4 g / cm ³ , or at least 0.6 g / cm ³ , specifically, at least 0.7 g / cm ³ . In this case, when the flow battery cell to which the carbon block is applied is fastened, the carbon block hardly shrinks, so that even when the battery cell is fastened, the porosity of the carbon block can be maintained. In this case, the higher the sintered density is, the better, the upper limit value is not specified.

In this case, the sintered density means the value measured by the test method specified in KS L 3409: 2010.

The carbon block may further perform heat treatment before battery fastening. Specifically, the carbon block may be heat-treated for a predetermined time at a high temperature while supplying air. At this time, the heat treatment temperature may be around 500 ℃, heat treatment time may be 5 hours or more and 7 hours or less.

In an exemplary embodiment of the present specification, the carbon felt means that the fiber produced by spinning the carbon or graphite material to form an irregular aggregate (meth shape) in the form of a plate.

In one embodiment of the present specification, the carbon felt layer is provided in an area of the bipolar plate that is not provided with the porous carbon block layer. This means that a portion of one surface of the bipolar plate is provided with a porous carbon block layer, and a region of the one surface of the bipolar plate not provided with the porous carbon block layer is provided with a carbon felt layer. That is, it means that there is a difference from the laminated structure of the carbon felt layer / porous carbon block layer / bipolar plate or the porous carbon block layer / carbon felt layer / bipolar plate.

In an exemplary embodiment of the present specification, the form of the surface where the carbon felt layer and the porous carbon block layer contact each other is not particularly limited. The shape of the surface where the carbon felt layer and the porous carbon block layer contact each other may be represented by a line in the cross section of the electrode. For example, the shape of the line where the carbon felt layer and the porous carbon block layer appearing in the cross section parallel to the bipolar plate may be a part of a polygon such as a straight line shape or a wavy pattern. The shape of this line is shown in FIG. 3.

3 (a) and 3 (b) show the shapes of lines in which the carbon felt layer of the electrode and the porous carbon block layer contact each other according to the exemplary embodiment of the present specification. It is shown here that the shape of the line is straight. In FIG. 3, a represents a carbon block layer, and b represents a carbon felt layer.

3 (c) to 3 (e) show the form of lines in which the carbon felt layer and the porous carbon block layer of the electrode according to the exemplary embodiment of the present specification are in contact. Here, it was shown that the shape of the line is in the form of a wave pattern. When the wave pattern is called a wavelength curve and the unit including one belly and a valley is called a unit wavelength, the wave pattern may include one unit wavelength ((c) of FIG. 3) and include two ( (D) of FIG. 3 may be included, and 3 or more may be included ((e) of FIG. 3).

3 (f) and 3 (g) show the shapes of lines in which the carbon felt layer and the porous carbon block layer of the electrode according to the exemplary embodiment of the present disclosure are in contact with each other. Here, the shape of the line may be a form in which two or more straight lines are connected, and a portion (hereinafter, referred to as a concave portion) in contact with the straight line may be in a form of a carbon felt layer or a porous carbon block layer. The part where two straight lines contact each other may have an angle of 1 degree or more and 150 degrees or less. The concave portion may be one as shown in FIG. 3 (f), or may be two or more as shown in FIG. 3 (h).

Figure 3 (i) shows the form of the line in contact with the carbon felt layer and the porous carbon block layer of the electrode according to an embodiment of the present disclosure. Here, the shape of the line may be part of an arc.

Specific forms of the electrode according to the exemplary embodiment of the present specification may be described with reference to FIGS. 2 and 3. 2 is a cross section in the direction A-A 'of the electrode of FIG. 1, that is, a cross section in the thickness direction of the electrode, and FIG. 3 is a cross section in a direction perpendicular to the thickness direction of the electrode. Thus, the cross-sections of FIGS. 2 and 3 are perpendicular to each other, and referring to c and 2, the three-dimensional shape of the electrode can be seen.

Figure 3 illustrates a cross-section in the direction perpendicular to the thickness direction of the electrode for secondary batteries of the electrode according to one embodiment of the present specification.

In one embodiment of the present specification, the secondary battery electrode further includes an electrolyte inlet and an electrolyte discharge part respectively provided on both sides of the secondary battery electrode.

In one embodiment of the present specification, any one of the porous carbon block layer and the carbon felt layer is provided on the electrolyte inlet side, the other provides a secondary battery electrode provided on the electrolyte discharge side. .

In one embodiment of the present specification, the electrolyte inlet means a portion where the electrolyte enters from the secondary battery electrode.

In one embodiment of the present specification, the electrolyte discharging unit means a portion from which the electrolyte is discharged from the secondary battery electrode.

In one embodiment of the present specification, any one of the porous carbon block layer and the carbon felt layer is provided on the electrolyte inlet side, the other is provided on the electrolyte discharge side. This is a structure for making different kinds of electrodes which an electrolyte solution pass along with the flow direction of electrolyte solution. For example, when the carbon felt layer is provided on the electrolyte inlet side, and the porous carbon block layer is provided on the electrolyte outlet side, when the electrolyte flows into the electrode through the electrolyte inlet, the carbon felt layer passes first, After passing through the porous carbon block layer, and exits the electrode through the electrolyte discharge portion.

In one embodiment of the present specification, the carbon felt layer may be provided on the electrolyte inlet side, and the porous carbon block layer may be provided on the electrolyte discharge side.

Secondary battery electrode according to an exemplary embodiment of the present specification, by disposing different electrodes on the electrolyte inlet or electrolyte discharge side as described above, has the advantage that the flow of the electrolyte can be efficiently controlled.

The flow of electrolyte in the electrode proceeds from the electrolyte inlet to the electrolyte outlet. Controlling the flow of electrolyte affects the performance of the cell. It is necessary to facilitate the movement of the electrolyte to facilitate the transfer of the electrolyte to the electrolyte discharge portion, while the electrolyte is evenly transferred from the electrolyte inlet to the electrolyte discharge portion, so that the reaction occurs evenly throughout the cell.

The effect may vary depending on the flow rate of the electrolyte. For example, under high flow conditions, the electrolyte may be well delivered to the electrolyte outlet, but the differential pressure inside the cell at the electrolyte inlet may be increased. On the contrary, in low flow conditions, the electrolyte is not delivered to the electrolyte discharge part well, and the electrolyte reacts at the electrolyte inlet part or at an intermediate point between the electrolyte inlet part and the discharge part, and the concentration of the electrolyte solution reaching the electrolyte discharge part is low. There is a problem that can fall.

In the secondary battery electrode according to the exemplary embodiment of the present specification, when the electrolyte solution has a high flow rate condition or a high output condition, the carbon felt layer may be provided on the electrolyte inlet side, and the porous carbon block layer may be provided on the electrolyte discharge part. In this case, since the electrolyte having a high ion concentration of the active material flowing from the electrolyte inlet is transferred to the electrode and the reaction occurs, not all the ions in the electrolyte participate in the reaction, so that an efficient electrode amount can be used. In addition, since the electrolyte may be quickly delivered by the porous carbon block layer provided in the electrolyte discharge part, the electrolyte may not be excessively stagnated and flow balance may be achieved.

In one embodiment of the present specification, the ratio of the horizontal area of the porous carbon block layer and the horizontal area of the carbon felt layer is 1: 1 to 5: 1, 1: 1 to 3: 1, preferably 1: 1. To 2: 1, most preferably 1: 1. When the numerical range is satisfied, the flow rate control of the porous carbon block layer and the carbon felt layer is appropriately adjusted, thereby maximizing battery performance.

The 'horizontal area' refers to the area of each layer in the horizontal direction of the porous carbon block layer or the carbon felt layer. When the cross section in the direction perpendicular to the thickness direction of each layer is observed, the area of each layer is determined. It may be meant.

In addition, the 'ratio of the horizontal area' may mean a ratio of each area measured by a method generally used in the art. For example, it can be measured by a method of measuring the longitudinal length of the electrode applied based on a constant horizontal length.

In one embodiment of the present specification, the porous carbon block layer and the carbon felt layer each contain pores, the average size of the pores of the porous carbon block may be more than 25㎛ 200㎛, preferably 25㎛ 120 micrometers or less, 70 micrometers or more and 120 micrometers or less, More preferably, they may be 90 micrometers or more and 110 micrometers or less. When the numerical range is satisfied, the differential pressure inside the cell or the stack can be maintained at a constant level during the flow of the electrolyte, and there is an effect of providing a plurality of reaction sites.

In one embodiment of the present specification, the porosity of the porous carbon block layer and the carbon felt layer is the same or different from each other, and may be 10% to 90%, or 40% to 90%, respectively. The porosity is adjusted to maximize the performance of each layer.

In one embodiment of the present specification, the porosity of the porous carbon block layer may be 10% to 70%, 20% to 50% or 30% to 45%. When the numerical range is satisfied, the electrolyte can diffuse quickly, and the differential pressure between the electrolyte inlet and the electrolyte discharge can be adjusted more delicately, and the differential pressure can be suppressed from becoming too high.

In one embodiment of the present specification, the porosity of the carbon felt layer may be 10% to 95%, 50% to 90% or 80% to 90%.

In one embodiment of the present specification, the porosity and the average size of the pores may be measured by a general method belonging to the art. For example, it can be measured using the method of ISO standard 2965.

In one embodiment of the present specification, the porosity and average size of the pores of the porous carbon block layer may have a profile. The method of having a concentration gradient is not particularly limited, and may have a concentration gradient by a method including an additional material such as metal particles during the production of the porous carbon block. Alternatively, the porous carbon block layer may be divided into two or more regions, and the porous carbon block layers may be prepared by different methods, and then the porous carbon block layers prepared in the desired gradient direction may be disposed.

In one embodiment of the present specification, the porosity of the porous carbon block layer may be increased from the electrolyte inlet side toward the electrolyte outlet side.

In an exemplary embodiment of the present specification, the average size of pores of the porous carbon block layer may increase from the electrolyte inlet side toward the electrolyte outlet side.

 In one embodiment of the present specification, the thicknesses of the porous carbon block layer and the carbon felt layer are the same or different from each other, and may be 1mm to 5mm, 1mm to 3mm, preferably 1mm to 2mm.

In one embodiment of the present specification, the thickness of the porous carbon block layer and the carbon felt layer may be the same.

In one embodiment of the present specification, the thickness of the porous carbon block layer and the carbon felt layer is different, the difference in thickness may be 4mm or less, 3mm or less, 2mm or less, 1.5mm or less, preferably 1mm or less, It may be 0.01 mm or more.

In one embodiment of the present specification, the thickness may be measured by a general method belonging to the art. For example, the thickness of each layer in the cross section of the thickness direction of the electrode may be measured by a scanning electron microscope (SEM) or a transmission electron microscope (TEM).

In one embodiment of the present specification, the density of the porous carbon block layer and the carbon felt layer is the same or different, preferably 0.05g / cm ³ to 2g / cm ³ , 0.05 / cm ³ to 1g / cm ³ , 0.1g / cm ³ to 1g / cm ³ . When the numerical range is satisfied, the fluid flow of the electrolyte solution is appropriately controlled to suppress the increase in the pressure difference in the battery, and the residence time of the electrolyte solution can be appropriately controlled therein. For example, when the density of the porous carbon block layer is less than 0.05 g / cm ³ , there is a problem that the residence time of the electrolyte is too low, and when the density of the carbon block layer is less than 2 g / cm ³ , the differential pressure in the battery becomes high. There is.

The density may be referred to as bulk density and may be measured by methods commonly used in the art. For example, a unit sample may be cut out to have any width, length, and thickness for a portion of each layer to calculate unit volume therefrom, and the weight of the unit sample may be measured to calculate the density.

In one embodiment of the present specification, the porous carbon block layer includes two or more kinds of porous carbon block patterns different from at least one of a density and a pore size, and the carbon felt layer has at least one of a density and a pore size. It may comprise two or more different carbon felt patterns.

In one embodiment of the present specification, the pattern may include a convex portion or a concave portion, and may include both the convex portion and the concave portion. The convex portion may have a convex shape in a direction opposite to the direction toward the bipolar plate with respect to the thickness direction of each layer, and the concave portion may have a concave shape in the direction toward the bipolar plate with respect to the thickness direction of each layer. In addition, the width and height of the pattern are not particularly limited.

One embodiment of the present specification provides a secondary battery including the secondary battery electrode.

In one embodiment of the present specification, the secondary battery electrode may be a secondary battery or a redox flow battery.

The secondary battery or redox flow battery may be manufactured using structures, materials, and methods known in the art, except for including the electrode structure described above.

5 shows an example of a redox flow battery. The bipolar plate 11, the electrode 12, the separator 13, the electrode 14, and the bipolar plate 15 are stacked in this order. In addition, the bipolar plates 11 and 15 may further include a flow path.

6 also shows an example of a redox flow battery. The redox flow battery is a battery cell 100 formed by electrically connecting unit cells 101, 102, 103, and 104 including unit stacks for generating current to each other, and supplying electrolyte to the unit cells. Electrolyte tanks 202 and 204 for storing the electrolyte discharged from the battery cell 100, and electrolyte pumps 302 and 304 for circulating the electrolyte between the battery cell 100 and the electrolyte tanks 202 and 204. Include.

The electrolyte solution stored in the electrolyte tanks 202 and 204 is not particularly limited, and electrolyte solutions known in the art may be used.

The electrolyte includes an active material and a solvent, wherein the active material includes a redox couple organic material that reacts electrochemically stably, and the solvent may be an aqueous solvent, an organic solvent, or a mixture thereof.

The electrolyte may be an anode electrolyte for the function of the anode or a cathode electrolyte for the function of the cathode, which includes a redox pair configuration. That is, in the case of the positive electrode active material, it refers to a redox pair dissolved in the positive electrolyte, and means that the redox pair is charged when the redox pair is changed to a higher one of two oxidation states, that is, oxidation occurs. In the case of the negative electrode active material, it refers to a redox pair dissolved in the negative electrode electrolyte solution, which means that it is charged to the lower side of two oxidation states of the redox pair, that is, when reduced.

The active material used in the present invention is not particularly limited, and an active material commonly used in the art may be used. For example, V, Fe, Cr, Cu, Ti, Sn, Zn, Br, etc. are mentioned. Such active materials can be obtained by a variety of redox pairs such as V / V, Zn / Br, Fe / Cr by a combination of oxidation and reduction differences. In the present invention, redox pairs made of V / V are used. Thus, using the same type of redox pair in the positive electrode and the negative electrode has the advantage of overcoming irreversible contamination due to the mixing phenomenon between the two electrodes, for example, the positive electrode electrolyte is V ^{4 +} / V ^{5 +} In the negative electrode electrolyte, V ²⁺ / V ³⁺ may be used as a redox pair.

According to one embodiment of the present specification, the concentration of the active material may be 0.01M or more and 4M or less, preferably 0.1M or more and 3M or less, more preferably 0.1M or more and 2 or less.

The aqueous solvent is one or a mixture of two or more selected from sulfuric acid, hydrochloric acid or phosphoric acid, and the organic solvent is acetonitrile, dimethyl carbonate, diethyl carbonate, dimethyl sulfoxide, dimethylformamide, propylene carbonate, ethylene carbonate, N-methyl-2-pyrrolidone, fluoroethylene carbonate, ethanol, methanol and gamma-butyrolactone may be one or a mixture of two or more thereof.

The electrolyte pumps 302 and 304 are not specifically mentioned in the present invention, and those known in the art may be used.

In an exemplary embodiment of the present specification, the material of the separator is not particularly limited as long as it can transfer ions, and may be one that is generally used in the art.

In one embodiment of the present specification, the separator may include a polymer having ion conductivity. The separator may be made of a polymer having ion conductivity, or may be provided with a polymer having ion conductivity in the pores of the porous body.

In one embodiment of the present specification, the polymer having ion conductivity is not particularly limited as long as it is a material capable of ion exchange, and those generally used in the art may be used.

In one embodiment of the present specification, the polymer having ion conductivity may be a hydrocarbon-based polymer, a partially fluorine-based polymer or a fluorine-based polymer.

In one embodiment of the present specification, the hydrocarbon-based polymer may be a hydrocarbon-based sulfonated polymer without a fluorine group, on the contrary, the fluorine-based polymer may be a sulfonated polymer saturated with a fluorine group, and the partial fluorine-based polymer is fluorine Sulfonated polymers that are not saturated with groups.

In an exemplary embodiment of the present specification, the polymer having ion conductivity is a perfluorosulfonic acid polymer, a hydrocarbon polymer, an aromatic sulfone polymer, an aromatic ketone polymer, a polybenzimidazole polymer, a polystyrene polymer, a polyester polymer Polymer, polyimide polymer, polyvinylidene fluoride polymer, polyether sulfone polymer, polyphenylene sulfide polymer, polyphenylene oxide polymer, polyphosphazene polymer, polyethylene naphthalate polymer, polyester It may be one or two or more polymers selected from the group consisting of a polymer, a doped polybenzimidazole polymer, a polyether ketone polymer, a polyphenylquinoxaline polymer, a polysulfone polymer, a polypyrrole polymer and a polyaniline polymer have. The polymer may be a single copolymer, an alternating copolymer, a random copolymer, a block copolymer, a multiblock copolymer or a graft copolymer, but is not limited thereto.

In one embodiment of the present specification, the ion conductor may be a polymer having a cationic conductivity, for example, Nafion, sulfonated polyetheretherketone (sPEEK), sulfonated polyether ketone (sPEK, Sulfonated (polyetherketone)), poly (vinylidene fluoride) -graft-poly (styrene sulfonic acid), PVDF-g-PSSA) and sulfonated polyflurolenyl ether It may include at least one of sulfonated poly (fluorenyl ether ketone).

In one embodiment of the present specification, if the porous body includes a plurality of pores, the structure and material of the body are not particularly limited, and those generally used in the art may be used.

For example, the porous body may be polyimide (PI), nylon, polyethylene terephthalate (PET), polytetrafluoro ethylene (PTFE), polyethylene (Polyethylene: PE), polypropylene ( polypropylene: PP), polyarylene ether sulfone (Poly), and polyetheretherketone (PEEK).

In one embodiment of the present specification, the average thickness of the separation membrane may be 20 μm or more and 200 μm or less, but is not limited thereto.

Hereinafter, the present specification will be described in more detail with reference to Examples. However, the following embodiments are only intended to illustrate the present specification, but the scope of rights is not limited thereto.

Example 1 Preparation of Electrode

Porous carbon block layer having the following conditions (manufactured using a PC009 porous carbon block manufactured by Comeksca Co., Ltd., porosity: 45%, thickness: 2.3mm, pressure when manufacturing the carbon block: 30kfg / cm ² , compressive strength: 29 ± 2Mpa, Sintered density: 0.76 g / cm ³ ) and an electrode comprising a carbon felt layer (manufactured by TOYOBO, XF30A). When the cross section in the direction perpendicular to the thickness direction of the electrode was observed, half was composed of a porous carbon block layer and the other half was composed of a carbon felt layer. At this time, the horizontal areas of the porous carbon block layer and the carbon felt layer were equal to each other (1: 1) with 16.25cm x 10cm = 162.5cm ² , and the total electrode area was 16.25cm x 20cm.

The electrode structure may be shown in FIG. 1, and the surface in which the porous carbon block layer and the carbon felt layer contact each other has a straight line shape (FIG. Indicated.

Porous carbon block layer Carbon felt layer Average size of pores 100 μm Not measured Porosity 45% 90% thickness 2.5 mm (0% compression) 3.53 mm (38% compression rate) density 0.6g / cm ³ or more 0.1g / cm ³

Comparative Example 1: Fabrication of Electrode

In the above embodiment, an electrode having an area of 16.25 cm x 20 cm was manufactured using only carbon felt, without using a carbon block layer. In other words, except that a carbon felt layer was used instead of the carbon block layer of Example 1, the same procedure as in Example 1 was carried out. Thus, an electrode having a single composition of the carbon felt layer was prepared.

Experimental Example

Example 2: Unit Cell Production

In order to confirm the performance of the unit cell, the electrode of Example 1 was stacked on top of the end plate and bipolar plate, respectively. At this time, the carbon felt layer (16.25 x 10 cm) was provided on the electrolyte inlet side, the carbon block layer (16.25 x 10 cm) was provided on the electrolyte outlet side. This form is shown in FIG.

A separator (Nafion 212) was stacked between the two electrodes. In the same manner, the electrode of Example 1 was again stacked, and a bipolar plate and an end plate were finally stacked to prepare a unit cell. As the electrolyte solution, 1 L of a 2.0 mol sulfuric acid solution (manufactured by OXKEM Co., Ltd.) containing 1.6 mol vanadium ions was circulated and supplied to the unit cell at an electrolyte flow rate of 1.0 L / min.

To the performance of the charging / discharging rate goes to 50 mA / cm, and ^two increments, each of the charge-per-step / discharged three times at 50mA / cm ² and up to 300mA / cm ² starts, the third charge / discharge cycle Table 2 Marked on.

Charge / discharge was performed in constant-current mode in the range of 0.5-1.6V.

[Comparative Example 2: Unit Cell Creation]

Except for using the electrode according to Comparative Example 1 instead of the electrode according to Example 1 was prepared and tested in the same manner as in Example 2, the results are shown in Table 2 below.

division Example 2 Comparative Example 2 Current density (mA / cm ² ) Dch (mAh) CE (%) VE (%) EE (%) Dch (mAh) CE (%) VE (%) EE (%) 50 31900 88.8 92.6 82.2 29971 89.7 92.2 82.7 100 28489 93.9 85.0 80.8 26127 93.4 85.6 80.0 150 23664 95.4 79.8 76.1 21474 94.0 79.2 74.5 200 17679 96.1 73.4 70.6 15918 95.2 72.3 68.8 250 11083 97.0 66.4 64.4 9209 96.7 64.5 62.4 300 3727 98.2 56.9 55.8 Not rated * Dch: Discharge capacity
* CE: current efficiency
* VE: voltage efficiency
* EE: energy efficiency

In Comparative Example 2, in the high current region having a current density of 300 mA / cm ² or more, the electrolyte flowability in the carbon felt was insufficient, and the electrolyte supply amount to the electrode required for evaluation was insufficient, so that evaluation could not be performed.

On the other hand, in the case of Example 2, it was confirmed that the discharge capacity is significantly improved compared to Comparative Example 2. This is because, as the electrolyte flows, the flowability of the electrolyte is improved by disposing the carbon block layer and the carbon felt layer in different areas that are separated from each other.

In the case of Comparative Example 2, in the case of the carbon felt, the electrolyte supply can be maintained even in a low current density region, but the electrolyte supply is insufficient when operating in a high current density region exceeding 50 mA / cm ² , the performance is sharply lowered. . This is because the pore size and porosity were reduced by the compression of the carbon felt layer. As a result, a high differential pressure was generated between the electrolyte inlet and the electrolyte outlet, resulting in energy loss.

 On the other hand, in the case of Example 2, it was possible to show higher efficiency than Comparative Example 2 even in the high current density region. This is because the battery of Example 2 was able to improve electrolyte flowability in the high current density region. Specifically, the carbon felt layer is disposed on the electrolyte inlet side, and the carbon block layer is disposed on the electrolyte outlet side, thereby effectively suppressing the occurrence of a high differential pressure between the electrolyte inlet and the electrolyte outlet.

Claims (13)

Bipolar plates;
A porous carbon block layer provided on a portion of one surface of the bipolar plate; And
Secondary battery electrode comprising a carbon felt layer provided in a region of the bipolar plate is not provided with a porous carbon block layer. The electrode for secondary batteries of claim 1, further comprising an electrolyte inlet and an electrolyte discharge part respectively provided on both side surfaces of the secondary battery electrode. The electrode of claim 2, wherein any one of the porous carbon block layer and the carbon felt layer is provided at the electrolyte inlet side, and the other is provided at the electrolyte discharge side. The method of claim 2, wherein the carbon felt layer is provided on the electrolyte inlet side,
The porous carbon block layer is a secondary battery electrode that is provided on the electrolyte discharge side. The electrode of claim 1, wherein the ratio of the horizontal area of the porous carbon block layer and the horizontal area of the carbon felt layer is 1: 1 to 3: 1. The method according to claim 1, wherein the porous carbon block layer and the carbon felt layer each comprises pores,
The average size of the pores of the porous carbon block layer is a secondary battery electrode is 25㎛ 200㎛. The method of claim 1, wherein the porosity of the porous carbon block layer and the carbon felt layer is the same or different from each other, each of the secondary battery electrode 10% to 90%. The method of claim 1, wherein the thickness of the porous carbon block layer and the carbon felt layer is the same or different from each other, each of the secondary battery electrode 1mm to 5mm. The electrode of claim 1, wherein the porous carbon block layer and the carbon felt layer have different thicknesses, and have a difference in thickness of 4 mm or less. The method of claim 1, wherein the density of the porous carbon block layer and the carbon felt layer is the same or different, each of the secondary battery electrode is 0.05g / cm ³ to 1g / cm ³ . The method of claim 1, wherein the porous carbon block layer comprises two or more kinds of porous carbon block patterns different in at least one of density and pore size,
The carbon felt layer is a secondary battery electrode comprising at least one carbon felt pattern different in at least one of the density and pore size. A secondary battery comprising the electrode for secondary batteries according to any one of claims 1 to 11. The secondary battery of claim 12, wherein the secondary battery is a redox flow battery.

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