KR20140026265A - Method of manufacturing electrolyte for vanadium secondary battery and apparatus thereof - Google Patents

Abstract

The present invention provides an economic and direct method of manufacturing an electrolyte for a secondary battery using cheap V2O5, in which insoluble pentavalent vanadium is not produced, and an apparatus including the electrolyte. According to the present invention, a sulfuric acid (H2SO4) aqueous solution is inserted in a half cell for oxidation, and a V2O5 dispersion and an H2SO4 aqueous solution are inserted in a half cell for reduction, respectively. Then, a potential is applied to an oxidation electrode and a reduction electrode by voltage of 1.7-2.5 V and current of 20-100 mA/cm2. The application of the potential is conducted by two steps. A trivalent vanadium solution (electrolyte for an anode) and a tetravalent vanadium solution (electrolyte for a cathode) may be economically manufactured by using cheap V2O5 (a pentavalent material) without generating insoluble pentavalent vanadium. [Reference numerals] (AA) Water or sulfuric acid

Description

Method of manufacturing electrolyte for secondary battery and apparatus therefor {Method of manufacturing electrolyte for Vanadium secondary battery and apparatus}

The present invention relates to a method for manufacturing an electrolyte solution for a vanadium secondary battery, and a device thereof, wherein 3 is used for a secondary battery without the production of a pentavalent vanadium using an inexpensive material, V ₂ O ₅ (a pentavalent material). The present invention relates to a method for producing an electrolyte solution for a secondary battery and an apparatus thereof, which can economically prepare a vanadium solution (cathode electrolyte) and a tetravalent vanadium solution (anode electrolyte).

Recently, renewable energy, such as solar energy and wind energy, has been spotlighted as a method for suppressing greenhouse gas emission, which is a major cause of global warming, and a lot of researches are being carried out for their practical use. However, the renewable energy is greatly affected by the location environment or natural conditions. Moreover, there is a disadvantage in that renewable energy cannot supply energy evenly continuously because the output fluctuates severely.

Therefore, in order to even out the energy output, it is important to develop a storage device that stores energy when the output is high and uses the stored energy when the output is low. Batteries and redox flow energy storage devices.

The lead acid battery has been widely used in the industry as a technology that is considerably more stable than other batteries, but has disadvantages such as low efficiency and maintenance costs due to periodic replacement and disposal of industrial waste generated during battery replacement.

The NaS battery has an advantage of high energy efficiency but has a disadvantage of operating at a high temperature of 300 ° C. or higher.

In contrast, redox flow energy storage devices are characterized by low maintenance costs, operable at room temperature, and independently designed capacity and output. In particular, redox flow energy storage devices, which use vanadium elements having various oxidation numbers as power storage materials, have great competitiveness in terms of economy and lifespan. It is true.

However, in order to obtain the positive and negative electrolytes (required tetravalent and trivalent solutions, respectively) required for the redox flow energy storage device, the conventional method is an electrolytic cell of the type shown in FIG. cell) to prepare an electrolyte from an aqueous starting solution of VOSO ₄ . In this case, a trivalent vanadium solution necessary for battery operation is obtained on the anode side, but at the same time, an insoluble substance, a pentavalent vanadium solution, is inevitably generated on the opposite cathode side, and thus recycled to the battery. This is very difficult, resulting in a decrease in economic efficiency and production efficiency.

In particular, VOSO ₄ , which is a raw material for obtaining trivalent vanadium solution (used as a cathode electrolyte of a vanadium redox flow energy storage device) and a direct anode electrolyte material, is expensive, has low cost-effectiveness, and increases electrolyte manufacturing cost. There was a problem.

Published Patent Publication No. 10-2011-0064058 (2011.06.15) Publication No. 10-2011-0088881 (2011.08.04) Published Patent Publication No. 10-2011-0119775 (2011.11.02)

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing an electrolyte solution for a secondary battery and an apparatus thereof, which can directly manufacture an electrolyte solution for a secondary battery economically without using inexpensive V ₂ O ₅ , without the generation of pentavalent vanadium. will be.

The present invention provides a method for producing a secondary battery electrolyte solution and apparatus for reducing a predetermined starting material (a hexavalent vanadium compound) in order to obtain a positive electrode electrolyte (tetravalent vanadium solution) and a negative electrode electrolyte (trivalent vanadium solution) required for a secondary battery. In

An oxidic half cell consists of an anode (anode) and water (distilled water) or an aqueous solution of 2-5 M sulfuric acid (H ₂ SO ₄ ) to collect electrons from inside the cell, and a cathode half cell. ) Is composed of a mixed solution of a cathode and a 1 to 3 M V ₂ O 5/2 to ₅ M H ₂ SO ₄ aqueous solution for supplying electrons into the cell,

The material in the oxidized half cell, i.e. water (distilled water) or 2-5 M sulfuric acid (H ₂ SO ₄ ) aqueous solution, is stirred with a stirrer and the material in the reduced half cell, i.e. 1-3 M V ₂ O ₅ /2-5 M H ₂ The mixed aqueous solution of SO ₄ is stirred by a stirrer, and a potential is applied to the oxidation and reduction electrode through a power supply at a voltage of 1.7 to 2.5 mA and a current of 20 to 100 mA / cm 2, but the application of the potential is a high constant current (about 100 ㎃ / ㎠)-the first step to cut-off at high voltage (about 2.5 Ｖ), and low constant voltage (about 1.7 Ｖ)-the second step to cut-off at low current (about 20 ㎃ / ㎠) It is. Alternatively, one or more moderate intermediate stages may be placed between the primary and secondary steps, with a constant constant current (about 80 mA / cm 2)-medium voltage, about 2 V).

The present invention has the effect of lowering the manufacturing cost of the vanadium secondary battery electrolyte using low-cost V ₂ O ₅ , and does not generate pentavalent vanadium that cannot be used as an electrolyte in the manufacturing step, thereby improving the efficiency and resource utilization of the process. .

In addition, the present invention is applied to the two electrodes of the electrolytic cell for the preparation of the electrolyte solution (reduction of V ₂ O ₅ ) to separate the power under two or more conditions (voltage and current conditions) to prevent damage to the device, shortening the reaction completion time It is effective to prepare an electrolyte solution quickly.

1 is an exemplary view showing a conventional electrolyte solution manufacturing apparatus configuration
2 is an exemplary view showing a configuration according to the present invention
3 is an exemplary view showing the configuration of an electrode-current collecting plate according to the present invention;
4 is an exemplary view illustrating the utility of the power application method (step 2) according to the present invention.

2 is an exemplary view showing a configuration according to the present invention, Figure 3 is an exemplary view showing a configuration of an electrode-current collector according to the present invention,

According to the present invention, the oxidized half cell 50 and the reduced half cell of an electrolytic battery cell 40 including an oxidation electrode 10, a reduction electrode 20, and an ion exchange diaphragm 30 provided between these two electrodes. In the electrolytic solution manufacturing apparatus 100 which supplies the oxidation tank electrolyte 70 and the reduction tank electrolyte 80 to 60, and applies a voltage and an electric current, and produces a redox reaction,

The oxidizing bath electrolyte 70 is made of water (distilled water) or 2-5 M sulfuric acid (H ₂ SO ₄ ) aqueous solution,

The reducing bath electrolyte 80 is composed of a mixed solution of 1 to ₃ M V ₂ O ₅ suspension and _{2 to 5} M H ₂ SO ₄ aqueous solution.

The oxidation electrode 10 and the reduction electrode 20 are configured to include an electrode fixing part, an electrode, and a current collector plate.

The electrode fixing part has a support function for compressing the electrode and fixing the electrode to the current collecting plate, and may be formed of an acid resistant plastic. At this time, the configuration of the electrode fixing unit is only one embodiment, any method that can be fixed to the electrode is possible.

The electrode is chemically stable in an electrolytic solution environment of sulfuric acid or hydrochloric acid solution and at the same time, a conductive porous substrate (eg, carbon or graphite) having sufficient conductivity and reaction area to receive electrons from the powder source and transfer them to the electrolyte, or vice versa. At least one of felt), carbon paper, a carbon or graphite powder mixture coated on a stable current collector plate, an acid resistant metal material (platinum, gold, etc.), or a gold / platinum coated metal electrode (titanium, stainless, etc.) It may include.

When the electrode is made of a conductive porous material such as carbon felt and carbon powder mixture, the current collector plate may include an acid resistant conductor which is a material having acid resistance / conductivity and capable of collecting electric charge from the electrode. The acid resistant conductor may be a non-metal current collector such as a carbon (or graphite) -plastic composite, a non permeable graphite plate, a graphite foil, or a gold / platinum coated metal current collector.

In addition, when the electrode is made of an impermeable material, it is possible to use a metal or alloy collector plate having good conductivity, such as copper and nickel.

As shown in FIG. 3, the oxidation electrode 10 and the reduction electrode 20 of the present invention configured as described above are supplied with current from the power supply 90 or current collector plates 11 and 21 for supplying current, and an electrolyte solution. The acid-resistant conductors 12 and 22 which prevent direct contact with the current collector plates and collect electrons from the electrodes and transfer them to the current collector plates, conductive porous materials 13 and 23 that transmit and receive electrons required for the reaction of the electrolyte, and conductive porous materials Most preferably, a stack of electrode fixing parts 14 and 24 for compressing and fixing the current collector plate is used.

In addition, the electrode fixing parts 14 and 24 may be formed in a mesh or frame shape using an acid resistant material.

In addition, the oxidation electrode 10 and the reduction electrode 20 of the present invention, around the current collector plate (11, 21), acid-resistant conductors (12, 22), conductive porous substrate (13, 23), electrode fixing part 14 24 may be stacked on one or both sides.

The electrolytic battery cell 40 is provided with a material that can withstand a strong acid electrolyte environment and the sealing structure does not leak the electrolyte solution, and can be used for a good chemical resistance and moldability material or an electrolytic cell coated with such a material or chemical resistant paint have. The material having good chemical resistance and moldability may include at least one selected from polyethylene, polypropylene, and the like.

The electrolytic battery cell 40 is generally rectangular in shape for the installation of the anode 10, the cathode 20, and the ion exchange diaphragm 30. It can be formed in various forms such as a cylinder.

When the ion exchange membrane 30 undergoes a redox reaction in the oxidized half cell and the reduced half cell through an electrolysis reaction, the ion exchange diaphragm 30 generates cations or anions in a specific direction in order to compensate for an imbalance in charge generated by the movement of electrons. A polymer resin film which can be moved or a diaphragm / bridge of inorganic material having the same role can be used. As a typical cation exchange membrane, an anion exchange resin having a structure such as a R-SO ₃ H, a cation exchange resin having an R-COOH structure, R-NOH, or a R-NH ₂ may be used. The ion exchange diaphragm 30 may be a commercially known one and may be used, for example, Nafion (Dupont), Neosepta (ASTOM), Selemion (Asahi), or the like.

The oxidizing bath electrolyte 70 uses water (distilled water), and it is preferable to use sulfuric acid (H ₂ SO ₄ ) to add 2-5 M sulfuric acid (H ₂ SO ₄ ) aqueous solution to ensure sufficient ion conductivity in the reactor. Do.

Such an oxidizing bath electrolyte 70 emits electrons capable of reducing V ₂ O ₅ of the reducing bath electrolyte 80 through an electrolysis reaction to allow the oxidation reaction to proceed, and removes harmful or unnecessary substances during the oxidation reaction. Do not create In addition, ₂ to 5 M sulfuric acid (H ₂ SO ₄ ) aqueous solution is used as the oxidizing bath electrolyte 70, but the material participating in the actual reaction is water, which is a solvent, and this is because the reduction potential of sulfate ion is sufficiently higher than that of the present invention. This is because the reaction hardly occurs under the reaction conditions. (After the manufacturing process is completed, it can be recycled in the next production only by adding water, which is a solvent.)

The reducing bath electrolyte 80 is composed of a mixed solution of 1 to ₃ M V ₂ O ₅ suspension and _{2 to 5} M H ₂ SO ₄ aqueous solution. The V ₂ O ₅ suspension has a very low solubility in water, but part of it is dissolved, but maintains a totally dispersed solution, so that H ₂ SO ₄ is mixed with continuous stirring to reduce and melt. Securing sufficient electrolytic properties to the trivalent and tetravalent vanadium ions coming out. In addition, in order to increase productivity per unit batch, high V ₂ O ₅ concentration is advantageous, but when the concentration exceeds 3 M, there is a problem that overvoltage and unbalance of charge distribution in the solution are caused. V ₂ O ₅ is preferred.

In FIG. 2, 110 is an oxidizing tank electrolyte tank, 130 is a reducing tank electrolyte tank, and the electrolyte tank and the action are well known techniques, and thus a detailed description thereof will be omitted.

According to the present invention, the oxidized half cell 50 and the reduced half cell of an electrolytic battery cell 40 including an oxidation electrode 10, a reduction electrode 20, and an ion exchange diaphragm 30 provided between these two electrodes. In the method of supplying the oxidizing bath electrolyte 70 and the reducing bath electrolyte 80 to 60, respectively, and causing an redox reaction by application of a voltage and an electric current,

Water (distilled water) or 2-5 M sulfuric acid (H ₂ SO ₄ ) aqueous solution in the oxidized half cell 50 is stirred by the stirrer 41,

The mixed solution of the 1 to ₃ M V ₂ O ₅ suspension and the _{2 to 5} M H ₂ SO ₄ aqueous solution in the reducing half cell 60 is stirred by the stirrer 41,

The power is applied to the oxidation electrode 10 and the reduction electrode 20 through the power supply 90 at a voltage of 1.7 to 2.5 mA and a current of 20 to 100 mA / cm 2,

The power is applied in the first step of high rate constant current charging (CC charging method = constant current) and in the second rate of low current charging (CV charging method = constant voltage) while maintaining low constant voltage. Made up of steps,

The first step is powered by a current of 100 mA / ㎠, cut-off voltage of 2.5 mA,

In the secondary step, electric power is applied at a voltage of 1.7 V and a cut-off current of 20 mA / cm 2.

In this case, when the applied potential exceeds 2.5 kV, components such as a current collector plate may be damaged, and when the stepped power applied by the first and second steps is performed under sufficiently high current conditions, the inside of the battery may be damaged. In order to solve the problem that the overvoltage occurs due to the resistance and the reaction is not completed, and reaches the set voltage, or the time taken to complete the reaction becomes too long when a very low current is applied to prevent such a phenomenon. will be. Depending on the device characteristics and needs, the steps can be further subdivided into 1st, 2nd, 3rd, etc. to increase process efficiency.

In the present invention made as described above, oxygen is generated from water or sulfuric acid in the oxidized half cell, and a tetravalent and trivalent vanadium solution, which is a positive electrode and a negative electrode electrolyte solution used in a secondary battery, is used from a solid state V ₂ O _{5 in a} half cell. It will be created at the same time.

Figure 4 shows an exemplary view illustrating the utility of the power application method (step 2) according to the present invention, Figure 4 (a) shows a graph showing the relationship between the magnitude of the applied current and the degree of progress of the overvoltage / reaction It can be seen that the higher the voltage is applied, the greater the overvoltage becomes, so that it is difficult to reach a sufficient degree of reaction progress at the same termination voltage. Therefore, in order for the reaction to proceed sufficiently, the termination voltage must be set high or charged with a low current. However, if the termination voltage is set high, component damage (corrosion, etc.) or side reactions (solvent decomposition, gas generation) can occur. When charging with current, a problem that takes a long time occurs, so the adjustment of power application has a great influence on the process efficiency.

Figure 4 (b) shows the efficiency at the time of CV charging (constant voltage, constant voltage charging) in the secondary system, the reaction after the reaction to a certain degree by high rate constant current charging (CC charging) in the first, insufficient reaction Secondary CV charging to compensate for progression, while the voltage of the cell is maintained in the CV charging, the applied current gradually decreases, so that the efficiency can be increased by appropriately adjusting the time and reaction degree as necessary.

The reaction in the oxidized half cell and the reduced half cell of the present invention configured as described above may not generate pentavalent vanadium, as well as harmful substances such as SO ₂ , Cl ₂ gas, and the like.

[Oxidation half cell-oxidation reaction]

_{2H 2 O → O 2 (↑} ) + 4H + + 4e -

[Reduction half cell-reduction reaction]

_{V 2 O 5 (s) +} 8H + + 3e - → V 3 + + VO 2 + + 4H 2 O

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined in the appended claims and their equivalents. Of course, such modifications are within the scope of the claims.

10: anode electrode 20: cathode electrode
(11,21): Current collector plate (12,22): Acid-resistant conductor
(13,23): Porous conductive material (14,24): Electrode fixing part
(30): ion exchange membrane (40): electrolytic battery cell
41: stirrer 50: oxidation half cell
60: reducing half cell 70: oxidizing bath electrolyte
(80): Reduction Tank Electrolyte (90): Power Supply
100: electrolyte solution manufacturing apparatus

Claims (8)

An oxidizing bath electrolyte and a reducing bath electrolyte are supplied to an oxidizing half cell and a reducing half cell of an electrolytic battery cell having an oxidizing electrode, a reducing electrode, and an ion exchange diaphragm provided between these electrodes, respectively, to supply voltage and current. In the electrolytic solution manufacturing apparatus which produces a redox reaction,
The oxidizing bath electrolyte contains water or an aqueous solution of 2-5 M sulfuric acid (H ₂ SO ₄ ),
The reduction tank electrolyte 80 is a secondary battery electrolyte production apparatus characterized in that it comprises a mixed solution of 1 to ₃ M V ₂ O ₅ suspension and _{2 to 5} M H ₂ SO ₄ aqueous solution.
The method of claim 1,
The oxidation electrode or the reduction electrode, the current collector is supplied with a current from the power supply or supply current; An acid resistant conductor that prevents the electrolyte from directly contacting the current collector plate and collects electrons from the electrode and transfers the electrons to the current collector plate; Conductive porous materials for transmitting and receiving electrons required for the reaction of the electrolyte solution; Electrode solution manufacturing apparatus for a secondary battery comprising a laminated; electrode fixing portion using an acid-resistant material for compressing the conductive porous material and fixed to the current collector plate.
The method of claim 2,
The acid resistance conductor is a carbon or graphite-plastic composite, an impermeable (non permeable) graphite plate, graphite foil, gold or platinum coated metal current collector, characterized in that it comprises at least one selected from the metal current collector plate.
The method of claim 2,
The conductive porous material is a secondary battery electrolyte manufacturing apparatus, characterized in that the carbon or graphite felt.
The method of claim 2,
The electrode fixing part is a secondary battery electrolyte manufacturing apparatus, characterized in that the shape of the mesh.
The oxidizing bath electrolyte and the reducing bath electrolyte are respectively supplied to the oxidized half cell and the reduced half cell of the electrolytic battery cell having an oxidizing electrode, a reducing electrode, and an ion exchange diaphragm provided between these electrodes, and application of voltage and current, respectively. In the method for producing an electrolyte by causing a redox reaction by
Stir in water or sulfuric acid (H ₂ SO ₄ ) aqueous solution in the oxidized half cell,
Stirring the mixed solution of the V ₂ O ₅ suspension and sulfuric acid (H ₂ SO ₄ ) aqueous solution in the reducing half cell,
The power supply is applied to the oxidation electrode and the reduction electrode with a voltage of 1.7 ~ 2.5 전류, current of 20 ~ 100㎃ / ㎠,
The power is applied in the first step of high rate constant current charging (CC charging method = constant current) and in the second rate of low current charging (CV charging method = constant voltage) while maintaining low constant voltage. Electrolytic solution manufacturing method for a secondary battery, characterized in that it comprises a step.
The method of claim 6, further comprising:
The first step is powered by a current of 100 mA / ㎠, cut-off voltage of 2.5 mA,
The secondary step is a secondary battery electrolyte manufacturing method, characterized in that the power is applied to the voltage 1.7V, cut-off current 20 mA / ㎠.
The method of claim 6, further comprising:
The aqueous solution of sulfuric acid (H ₂ SO ₄ ) is a 2-5 M aqueous solution of sulfuric acid (H ₂ SO ₄ ), and the V ₂ O ₅ suspension is a 1-3 M V ₂ O ₅ suspension.

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