Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/18—Regenerative fuel cells, e.g. redox flow batteries or secondary fuel cells
  • H01M8/184—Regeneration by electrochemical means
  • H01M8/188—Regeneration by electrochemical means by recharging of redox couples containing fluids; Redox flow type batteries

Definitions

• the invention relates to energy storage devices that belong to the technical field of energy storage technologies and can be used for renewable energy sources such as solar and wind, have no negative risks such as combustion, explosion, and thermal deposition, as well as can obtain high potential values.
• the invention is mainly related to obtaining new redox couples to provide the said features for use in the described energy storage devices.
• Redox fluid batteries have the flexibility to be designed specifically for systems since the energy they store and the power parameters they provide are independent of each other. In this way, the said batteries can be used for large-scale energy storage applications. Redox flow batteries can provide solutions especially for ensuring the continuity of renewable energy sources such as solar and wind and for power consumption balance and supply.
• Battery systems are designed to meet application-specific technical demands such as the energy capacity they will store, the power they can provide, charge/discharge profiles, operating temperatures, ergonomic features, etc. According to the US Department of Energy data, an energy storage system, which will cost USD 100 per kWh as of 2030, is considered economically reasonable.
• Redox Flow Battery technology stands out as a promising technology among electrochemical energy storage technologies, especially due to its low cost and scalability.
• researchers around the world carry out electrode, electrolyte development, and cell design studies for less costly, energy storage, and energy supply performance has been increased and platforms to be used are unique designs.
• Redox fluid batteries are a type of rechargeable battery that stores electrical energy.
• External electrolyte tanks can typically be dimensioned in accordance with application requirements.
• the said external electrolyte tanks have two soluble redox couples.
• Liquid electrolytes are pumped from the storage tanks to the flow electrodes. In the flow electrodes, chemical energy is converted to electrical energy (discharge) or vice versa (charge).
• the electrolytes flowing along the anode and cathode are generally different and are expressed as anolyte and catolyte, respectively.
• a membrane or separating membrane between the anode and cathode chambers, which selectively permits crosstransport (cross-transport) of inactive species (e.g., H+, CI-) to maintain electrical neutrality and electrolyte balance.
• inactive species e.g., H+, CI-
• capacitors and batteries from the main systems used for storing energy other than redox fluid batteries, carbon-based conventional energy sources, alternative (renewable) energy sources, and energy are widely used to meet this energy demand.
• the present invention relates to energy storage devices and new redox couples that can be used in the said energy storage devices to eliminate the above-mentioned disadvantages and to bring new advantages to the related technical field.
• the object of the invention is to provide an energy storage device with high voltage values.
• the object of the invention is to provide an energy storage device that does not have the risk of ignition, explosion, and combustion.
• the object of the invention is to provide an energy storage device that has no adverse effects on the environment and air, such as lead and fossil fuels, such as pollution, global warming, and acid rain.
• An object of the invention is to provide an energy storage device in which there is no thermal precipitation problem.
• the invention belongs to the field of energy storage technologies and relates to an energy storage device that is suitable for use in renewable energy sources such as solar and wind and is based on the storage of electrical energy from electrochemical reactions.
• the energy storage device of the invention consists essentially of at least two half cells, the said half cells are separated from each other by a non-permeable semi-permeable membrane for redox couples, and each half cell includes at least one electrode; it comprises chromium ions in the half cell where the oxidation reactions take place and cerium ions in the half cell where the reduction reactions take place; the said chromium and cerium ions are dissolved or dispersed in the organic solvent, water and/or inorganic acid in the half cells, and further comprises at least one of the conductive salts, redox reactive auxiliary components and/or electrolyte solutions in the half cells to improve energy storage performance if necessary.
• the chromium and cerium ions are dissolved in the half cells and the solvent is liquid inorganic acids.
• the said liquid is at least one of hydrochloric acid and/or sulfuric acid or a mixture in certain proportions.
• concentration of cerium ions is in the range of 0.001 M to 2 M in the half cell solution.
• the concentration of cerium ions is in the range of 0.1 M to 1 M in the half cell solution.
• the concentration of cerium ions is 0.2 M in the half cell solution.
• the concentration of chromium ions is in the range of 0.001 M to 2 M in the half cell solution.
• the concentration of chromium ions is in the range of 0.1 M to 1 M in the half cell solution.
• the concentration of chromium ions is 0.2 M in the half cell solution.
• the concentration of inorganic acids is in the range of 0.001 M to 7 M in the half cells.
• the concentration of inorganic acids contained in the half cells is in the range of 0.1 M to 5 M.
• the concentration of inorganic acids contained in the half cells is 4 M.
• Figure 1 shows the representative view of the half cells in which the redox reactions may take place in the energy storage device according to the invention.
• Figure 2 shows the cyclic voltammogram values of the energy storage device obtained with solutions containing 0.2 M Ce +4 and 0.2 M Cr +3 ions in 4 M sulfuric acid.
• Figure 3 shows the five-cycle charge/discharge curve for the Cr/Ce redox couple.
• the subject of the invention is related to the energy storage devices that can be used for renewable energy sources such as solar and wind and where high potential values can be obtained and the redox couples used in the said energy storage devices and is explained with examples that do not have any limiting effect only for a better understanding of the subject.
• the term energy storage device according to the invention is used in the broadest sense.
• the expression battery may also be used as an energy storage device if preferred.
• the energy storage device of the invention may comprise a complex structure comprising half cells, membranes, electrodes, and other circuit elements in which a single electrochemical reaction takes place, and in which many electrochemical reactions take place.
• the energy storage device of the invention contains anolytical and catolytical cerium and chromium ions and is based on electrochemical reactions between these ions. Accordingly, the energy storage device is for storing electrical energy based on electrochemical redox reactions.
• the energy storage device contains polarity-specific half cells separated from each other by the membrane and filled with a liquid fed by pumps from at least two separate tanks of the desired size.
• the said half cells contain water, organic solvents, and/or inorganic acids at certain concentric values.
• half cells contain inorganic acid.
• hydrochloric acid to be abbreviated as HCI
• sulfuric acid to be abbreviated as H2SO4
• HCI hydrochloric acid
• H2SO4 sulfuric acid
• the half cells contain the same inorganic acids as the liquid. In particular, it contains H2SO4 as inorganic acid within the half cells.
• the half cells in the energy storage device contain redox activities that allow the voltage to be obtained in the electrodes.
• These redox active substances may be completely dissolved or dispersed in water, organic solvent, and/or inorganic acid in the half cells.
• the redox active substances in the half cells may also be present in solid form.
• the main embodiment of the invention is that redox active substances are included as components in at least one inorganic acid mixture. HCI and H2SO4 are preferably present as inorganic acids.
• Redox active substances are taken from at least one tank and pumped into the electrodes as electrolyte solutions (anolyte and/or catolytes are expressed).
• the said electrodes are anode and cathode compartments, as is known.
• the anode and cathode electrodes are separated from each other by at least one semi-permeable membrane, which is highly selective for protons, within the energy storage device.
• Redox active substances are transmitted to anode and cathode half cells according to their oxidation and reduction activities. Current can be received from the system as electrolytes are transmitted from the tanks to these half cells using pumps.
• the main parameter indicating the effectiveness of the energy storage device is the voltage value obtained.
• the receivable voltage value is related to the efficiency of the electrochemical reaction, which is directly proportional to the size of the electrolyte supply tanks.
• the tank size can be adjusted according to the size of the energy to be stored here, and the tank size determines the size of the system by directly affecting the dimensions of the energy storage device.
• the invention proposes the use of cerium (to be abbreviated as Ce) and chromium (to be abbreviated as Cr) ions as redox active substances in energy storage device half cells.
• the anode half cell (hereinafter referred to as the anode part only) is the part where the oxidation reaction takes place in redox reactions; Cr ions are included as redox active ions.
• the reaction which is expressed as (1 ), takes place to store energy in the anode part.
• the cathode half cell (hereinafter referred to as the cathode part only) is the part where the reduction reaction takes place in the redox reactions, and in this part, Ce ions are included as redox active ions.
• the reaction which is expressed as (2), takes place to store energy in the cathode part.
• Figure 1 shows representatively the half cells in which a single redox reaction may take place in the energy storage device according to the invention.
• the energy storage device includes a cathode and cathode tank, pump; anode portions and anode tank, pump, a semipermeable membrane, and current collectors.
• the circuit elements cathode and anode parts.
• current collector within the energy storage device; circuit elements that enable the collection of the current obtained as a result of the reactions in the half cells; fittings and inputoutput parts that enable the transmission of electrolytes from the tanks to the anode and cathode parts and the entry to the half cells.
• the anode and cathode parts are separated from each other by semipermeable membranes.
• the half cells contain redox active substances and fluids that allow redox reactions to take place, as well as auxiliary components, catalysts, or active substances that improve the performance of the reactions.
• the energy storage device of the invention is essentially an embodiment containing redox active substances of half cells in inorganic acid. Other auxiliary components that will improve the performance of this embodiment are not outside the scope of the protection of the invention.
• the main embodiment of the invention is a redox fluid reaction system containing Cr ions in the H2SO4 solution in the anode part and Ce ions in the H2SO4 solution in the cathode part.
• sulfuric acid can vary, for example, HCI can be used.
• HCI can be used.
• the use of inorganic acid is the main embodiment, an invention that can be obtained by the change of the acid type is within the scope of protection of this invention.
• the electrode, current meter, circuit elements, tanks, and pumps used in the invention are not essential for the subject of the invention, and the tools used in the art can also be used here. In addition, the change of these tools is also included in the protection scope of the invention.
• the concentrations of redox active substances used in energy storage device half cells are in the range of 0.001 M to 2 M.
• concentrations of Ce and Cr ions, which are preferably used as half cell redox active substances, are in the range of 0.1 to 1 M.
• concentrations of the most preferred Ce and Cr ions are 0.2 M in the half cell.
• the concentrations of inorganic acid used in energy storage device half cells are in the range of 0.001 M to 7 M.
• concentrations of H2SO4 and/or HCI, which are preferably used as half cell inorganic acids, are in the range of 0.1 to 5 M.
• the most preferred inorganic acid concentrations are 4 M in the half cell.
• the said concentration values were determined as a result of the experimental setups prepared by the inventors and are entirely the product of research and development studies.
• the resistance, double layer capacitance value, load transfer resistance, and impedance values of the solution containing Ce +3 ions at 0.2 M concentration and various molar concentrations of sulfuric acid are given in Table 1 .
• Table 1 Calculated resistance, double-layer capacitance, load transfer resistance, and impedance values of the solution obtained by adding 0.2 M Ce and sulfuric acid at various concentrations.
• the resistance, double layer capacitance value, load transfer resistance, and impedance values of the solution containing Ce+3 ions in different concentrations (0.050 M, 0.075 M, 0.1 M, 0.15 M, 0.2 M) to the solution containing 4 M H2SO4 are given in Table 2.
• Figure 2 shows the cyclic voltammogram values of the obtained energy storage device with solutions containing 0.2 M Ce +4 and 0.2 M Cr +3 ions in 4 M sulfuric acid. While the charge potential value of the energy storage device is given between the reduction potential of chromium and the oxidation potential of cerium, the battery discharge potential value is given between the oxidation potential of chromium and the reduction potential of cerium. The oxidation peak of the Ce(lll) ion to the Ce(IV) ion was observed at approximately 1 .6 V, while the reduction peak was observed at approximately 1 .2 V. According to this data, the operating potentials of the energy storage device during the charging and discharge processes were determined as 1 .2 V and 0.7 V, respectively.
• Cyclic charge-discharge tests were also carried out to determine the discharge capacity of the energy storage device of the invention.
• the five-cycle charge/discharge curve for the Cr/Ce redox couple is shown in Figure 3.
• Discharge capacities were found to be 20 mAh L’ 1 , 20.4 mAh L’ 1 , 20.8 mAh L’ 1 , 21 .1 mAh L’ 1 , 21 .2 mAh L -1 for the first cycle, second cycle, third cycle, fourth and fifth cycles, respectively.
• energy storage device discharge capacities increase during cycle tests.
• Ce/Cr redox couples have been used in different oxidation steps in acidic environments as electrolyte solutions of redox flow batteries for the first time in the relevant technical field. Indeed, for the redox flow battery system, this new redox couple has a relatively higher discharge potential value of 1 .52 V, which is about 0.32 V higher than the theoretical cell potential. The resulting cell potential value is higher than the nominal voltage value ( ⁇ 1 .26 V) of the vanadium redox battery systems.
• the energy storage device of the invention consists of a structure that does not contain fossil fuel or lead components, it does not cause pollution to the environment, air and has no negative effects such as acid rain formation.

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Citations (2)

• 2021
  • 2021-10-01 TR TR2021/015353A patent/TR2021015353A2/tr unknown
• 2022
  • 2022-09-29 WO PCT/TR2022/051064 patent/WO2023055332A1/en unknown

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