Patent Application
20190305344
The present invention relates to a redox flow battery including an electrolyte concentration measuring instrument.
Recently, a redox flow battery has been attracting the greatest attention as one of the core products closely associated with renewable energy, reduction in greenhouse gas, secondary batteries, and smart grids. Currently, most of the energy is obtained from fossil fuels, but the use of these fossil fuels has a serious adverse impact on the environment such as air pollution, acid rain, global warming, and low energy efficiency.
In recent years, in order to address the problems, interests in renewable energy and fuel cells have rapidly increased. Interests and researches on such renewable energy are being developed not only domestically but also globally.
Although the renewable energy market has entered the mature stage both domestically and internationally, there is a problem that the amount of generated energy changes according to environmental conditions such as time and weather which are the properties of renewable energy. As a result, an energy storage system (ESS) for storing the generated renewable energy is very demanded to stabilize the grid and the redox flow battery is attracting attention as a large-scale energy storage system.
As an embodiment of the present invention, a structure of the redox flow battery includes a stack 1 with a plurality of cells for electrochemical reaction are stacked, cathode and anode inlet pipes 2A and 2B, catholyte and anolyte tanks 3A and 3B for storing catholyte and anolyte, and pumps 4A and 4B for supplying the catholyte and the anolyte to the stack from the tanks, as illustrated in
An important factor in determining an energy capacity of the redox flow battery is an equilibrium state of active materials in the catholyte and the anolyte. In the redox flow battery, an ion exchange membrane must be used to form an electric circuit. Theoretically, a cation exchange membrane needs to transfer cations and an anion exchange membrane needs to transfer anions. However, actually, undesired ions are transferred by a concentration difference therebetween and water molecules and a balance of the cathode and anode active material concentrations of determining the capacity is broken. Therefore, in order to maintain a constant capacity of the redox flow battery for a long time, a rebalancing operation is necessary and it is necessary to check the state of the active materials in the catholyte and the anolyte in real time for the rebalancing.
For the rebalancing, firstly, the concentrations of the active materials in the electrolyte need to be measured and the electrolyte needs to be sampled and diluted to a certain multiple in order to measure the concentration with a common analyzer.
Since most concentration analyzers are for laboratory rather than for portable, sampling for the analysis is required in the field.
Generally, it is practically impossible to always perform sampling because a distance between the field and the laboratory is long. Therefore, there is a limitation to measuring the electrolyte concentration using the existing methods.
Regarding the redox flow battery electrolyte, there is Korean Patent Registration No. 10-1130575, which is intended to produce vanadium ions, but is not related to the measurement of the electrolyte concentration.
(Patent Document 1) Korean Patent Registration No. 10-1130575 (registered on Mar. 20, 2012)
The present invention relates to a redox flow battery including an electrolyte concentration measuring instrument and is directed to measure a concentration of an electrolyte in real time even during charging and discharging and to real time rebalance the electrolyte for maintaining a high energy capacity.
The present invention is directed to measure a concentration of an electrolyte through a real time communication process, not analysis by a diluting process of a sample after sampling in the field.
The present invention relates to a redox flow battery comprising: an electrolyte tank, an electrolyte inlet pipe, a stack, and a pump supplying an electrolyte in the tank to the stack through the electrolyte inlet pipe, wherein an electrolyte concentration measuring instrument is connected to the electrolyte inlet pipe.
The electrolyte concentration measuring instrument may be connected to an electrolyte inlet pipe by a pipe bypassed to the electrolyte inlet pipe, and the electrolyte transferred to the stack from the electrolyte tank may pass through the electrolyte concentration measuring instrument and then flow into the electrolyte inlet pipe again.
The electrolyte concentration measuring instrument may include a light emitting unit emitting light in a specific wavelength range, a light receiving unit receiving the emitted light, an inlet port to which the electrolyte is introduced, an outlet port from which the electrolyte is discharged, and a container connected with the inlet port and the outlet port between the light emitting unit and the light receiving unit and filled with the electrolyte, and the light emitted from the light emitting unit may pass through the container and then is received at the receiving unit.
In the electrolyte concentration measuring instrument, a relational formula between a concentration value of the electrolyte and a sensor value measured by the light receiving unit may be established based on a plurality of reference data, and then the concentration value of the electrolyte may be obtained by measuring the sensor value.
The electrolyte inlet pipe may be a cathode inlet pipe or an anode inlet pipe.
In the electrolyte concentration measuring instrument, spacers may be installed on both sides of the container and a substrate on which electronic components including the light emitting unit or the light receiving unit are mounted may be installed in each spacer.
The electrolyte concentration measuring instrument may measure the concentrations of two active materials in one of catholyte and anolyte and the concentrations of two active materials in the other of catholyte and anolyte may be calculated based on the measured concentrations.
According to the present invention, it is possible to figure out a state of charge (SOC) during charging and discharging and find a crossover problem through an ion exchange membrane in real time by an electrolyte concentration measuring instrument.
Further, it is possible to figure out a molar difference in active materials between the catholyte and the anolyte through the measured concentration and volume and to perform rebalancing in real time.
Further, it is possible to improve an energy capacity through real-time rebalancing and to measure an electrolyte concentration and figure out an electrolyte state in real time without electrolyte sampling in the field and diluting the sampled electrolyte.
Therefore, it is possible to reduce the labor costs for sampling and analysis in the field, and particularly, it is possible to remotely figure out a real-time electrolyte state and perform rebalancing for maintaining a high capacity state even when a product is installed in a foreign country.
The present invention may have various modifications and various embodiments and specific embodiments will be illustrated in the drawings and described in detail in the detailed description. Advantages and features of the present disclosure, and methods for accomplishing the same will be more clearly understood from embodiments described in detail below with reference to the accompanying drawings. However, the present disclosure is not limited to embodiments disclosed below but may be implemented in various different forms. A singular form may include a plural form if there is no clearly opposite meaning in the context. Further, the terms “including”, “having”, etc. mean that there is a feature or a component described in the specification and it is not excluded a possibility that one or more other features or components may be added.
Also, terms “connected” and “connecting” refer to “directly or indirectly connected” and “directly or indirectly connecting”.
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, in which the same or corresponding reference numerals refer to the same or corresponding elements regardless of reference numerals and a duplicated description thereof will be omitted.
As such, the bypass pipe is installed at an electrolyte inlet pipe (2A or 2B) supplying the electrolyte to the stack so that the electrolyte passes through the electrolyte concentration measuring instrument and then flows to the electrolyte inlet pipe again, thereby measuring the concentration of the electrolyte supplied to the instrument without requiring a circulation device such as an additional pump.
In
In the redox flow battery, the ratio of an active material in an oxidized state to an active material in a reduced state which are contained in the catholyte changes depending on charging/discharging state. Also, in the anolyte, there exist different ratios in active materials of an oxidized state and a reduced state. That is, the active materials in the four states are present at different ratios depending on a charging/discharging process, but regardless of the state of charging and discharging, the entire active materials contained in the catholyte and anolyte always satisfy the same molar equilibrium and charge equilibrium as the state of the entire active materials contained in the initial catholyte and anolyte.
Therefore, if the concentrations of the active materials in the two states among the four states are known, the concentrations of the active materials in the remaining two states may be known through molar equilibrium and charge equilibrium equations of the entire active materials.
As a result, the present invention includes the electrolyte concentration measuring instrument to figure out the concentration of the active materials in the remaining two states by measuring the concentrations and volume of the active materials in the two states among the active materials in the four states and figure out a molar difference in entire active materials of the catholyte and the anolyte, thereby more accurately enabling rebalancing in real time.
The electrolyte concentration measuring instrument measures the concentrations of active materials in a specific state, thereby more accurately enabling rebalancing in real time.
In
The container 25 is located between the light emitting unit 23 emitting light in a specific wavelength range and the light receiving unit 24 receiving the light and the light having the specific wavelength may be penetrated through the container.
The absorbance varies depending on a material, a color and a thickness of the container 25 and a distance between the light emitting unit and the light receiving unit.
In the present invention, the container 25 has a thickness of 1 mm to 15 mm and may be made of a material such as transparent plastic, glass, acryl, or the like. The distance between the light emitting unit and the light receiving unit may be 1 mm to 20 mm and the distance between the light emitting unit 23 and the light receiving unit 24 may be adjusted.
The electrolyte, the concentration of which is to be measured, is introduced to an input port 21 of the electrolyte concentration measuring instrument 20 and passes through the container 25 and then the electrolyte is discharged to an output port 22. Therefore, measuring the electrolyte concentration does not affect a normal operation of the redox flow battery and the entire system may measure the concentration of the electrolyte in real time without stop.
A printed circuit board 27 including a sensor is installed to traverse the spacer, and the input port 21 and the output port 22 are installed on one side.
As such, the input port 21 and the output port 22 may be configured on one side, and may also be installed on opposite sides of the container 25 as illustrated in
A reference data test refers to a process of obtaining the relational formula by plotting the sensor value and the concentration value using an electrolyte sample.
The relational formula between the sensor value and the concentration value is obtained through the reference data test, and the sensor value read in real time is applied to the relational formula to obtain the concentration of the electrolyte.
Specifically, when charging is performed in a vanadium redox flow battery, vanadium ions (=active materials) are present as V3+ and V2+ states in the anolyte and as V4+ and V5+ states in the catholyte until the SOC reaches 100%. According to the instrument of the present invention, concentrations of V3+ and V2+ contained in the anolyte supplied to an anode inlet of the stack may be measured by the electrolyte concentration measuring instrument 20 in real time without an additional diluting process.
For example, since the absorption range of V3+ is 389 nm, a circuit of the electrolyte concentration measuring instrument may be configured using a light emitting unit and a light receiving unit having a ultraviolet absorption range, and since the absorption range of V2+ is 850 nm, a circuit may be configured using a emitting unit and a light receiving unit having an infrared absorption range (see
In order to for measure concentrations of two active materials of an electrolyte respectively, the electrolyte concentration measuring instrument may comprise two different light emitting units emitting two different lights and two different light receiving units receiving the two different lights. Also, the electrolyte concentration measuring instrument may comprise two circuits for the different lights.
The aforementioned present invention is not limited to the aforementioned embodiments and the accompanying drawings, and it will be obvious to those skilled in the technical field to which the present invention pertains that various substitutions, modifications, and changes may be made within the scope without departing from the technical spirit of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2018-0035505 | Mar 2018 | KR | national |
