10 h) storage of clean energy generated in rural areas. This projectalso wants to explore the possibility of using freights and pipelines for transporting clean electricity from countrysides to end-users in metropolises. A flow battery separates electrolyte reservoirs from two electrodes. When it is charged, electricity is converted to chemical energy, which is stored in iron (III) and titanium (III) salts that are dissolved in two aqueous solutions, respectively. Such water-based electrolytes can be transported from a rural area via, for example, trucks, trains, boats, or pipelines to another battery cell in a different location, where charged electrolytes will be pumped through the electrode compartments of the second cell--converting chemical energy back to electricity. The spent electrolytes comprised of iron (II) and titanium(IV) will be brought back to the original cell in the rural area for recharging. If it works, this strategy could solve the transmission and distribution problem of renewable energy--potentially transforming rural areas into the energy production centers of the U.S., and enabling the export of clean energy to the larger global market. The major goals of this project include: (1) increasing the energy density of charged electrolytes by varying the composition of iron and titanium water solutions, respectively, for reducing electrolyte transportation costs; and (2) optimizing the cell structure for improved battery performance.' />
Source: ENERGAO, INC. submitted to
IMPROVING THE ENERGY DENSITY AND PERFORMANCE OF DETACHABLE REDOX FLOW BATTERIES
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
SMALL BUSINESS GRANT
Reporting Frequency
Annual
Accession No.
1028490
Grant No.
2022-33530-37068
Cumulative Award Amt.
$125,000.00
Proposal No.
2022-01273
Multistate No.
(N/A)
Project Start Date
Jul 1, 2022
Project End Date
Feb 29, 2024
Grant Year
2022
Program Code
[8.6]- Rural & Community Development
Project Director
Jiang, R.
Recipient Organization
ENERGAO, INC.
754 STONE CREEK DR
MAKANDA,IL 629582748
Performing Department
(N/A)
Non Technical Summary
The U.S. Census Bureau estimated that in 2020, approximately 57.23 million people live in rural regions, compared to about 272.91 million people living in urban areas.On the other hand, urban areas make up only 3 percent of the entire land area of the U.S. Conversely, 97 percent of the country's landmass is rural but only 19.3 percent of the population lives there.During recent years, the rapid adoption of electric vehicles, especially in urban areas, has increased the demand for electric power. Climate change has driven the increased production of clean and renewable energy. Rural areas contribute to 97 percent of the nation's lands, which can be utilized for harvesting solar and wind electricity. Unfortunately, this also creates a geographic mismatch between clean energy production and consumption. The first grid in the U.S. was built in 1882 in Manhattan and New Jersey, and our power distribution systems were expanded since then and until the 1960s.For a power grid to remain stable, it needs to respond to volatility in voltage and frequency disturbances. If there is a mismatch of power generation and consumption, complete adjustments are necessary within an acceptable timeframe to balance the frequency disturbances and power outages. Equilibrium is what is most important for grid systems. In other words, our nationwide grid systems were built based on the continuous and steady supply of power from coal-fired power plants--not from renewable sources. Our existing grid infrastructures are not well suited for transmitting and distributing clean electricity from rural areas to urban cities. Climate change as well as the significant reduction of lithium-ion battery costs have led to the development of electric vehicles for agricultural applications. A detachable iron-titanium battery instead of a lithium-ion battery can be used for powering agriculture vehicles. A distinctive advantage is that a flow battery can be recharged by simply swapping the electrolyte storage tanks--allowing the continuous operations of the equipment in farm fields. In this project, we aim to develop a novel iron-titanium redox flow battery with two detachable electrolyte storage tanks. Iron-titanium batteries cost $80/kWh for energy storage--lower than $369/kWh of lithium-ion batteries, and $399/kWh of vanadium flow batteries. An iron-titanium battery employs no self-igniting materials and its electrolytes are comprised of ~60% water--deeming it fire safe. As a result, iron-titanium batteries could be ideal devices for fire-safe, low-cost, and long-duration (>10 h) storage of clean energy generated in rural areas. This projectalso wants to explore the possibility of using freights and pipelines for transporting clean electricity from countrysides to end-users in metropolises. A flow battery separates electrolyte reservoirs from two electrodes. When it is charged, electricity is converted to chemical energy, which is stored in iron (III) and titanium (III) salts that are dissolved in two aqueous solutions, respectively. Such water-based electrolytes can be transported from a rural area via, for example, trucks, trains, boats, or pipelines to another battery cell in a different location, where charged electrolytes will be pumped through the electrode compartments of the second cell--converting chemical energy back to electricity. The spent electrolytes comprised of iron (II) and titanium(IV) will be brought back to the original cell in the rural area for recharging. If it works, this strategy could solve the transmission and distribution problem of renewable energy--potentially transforming rural areas into the energy production centers of the U.S., and enabling the export of clean energy to the larger global market. The major goals of this project include: (1) increasing the energy density of charged electrolytes by varying the composition of iron and titanium water solutions, respectively, for reducing electrolyte transportation costs; and (2) optimizing the cell structure for improved battery performance.
Animal Health Component
60%
Research Effort Categories
Basic
0%
Applied
60%
Developmental
40%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
5117410200070%
5117410202030%
Knowledge Area
511 - New and Improved Non-Food Products and Processes;

Subject Of Investigation
7410 - General technology;

Field Of Science
2020 - Engineering; 2000 - Chemistry;
Goals / Objectives
In this project, we aim to develop a novel iron-titanium redox flow battery with two detachable electrolyte storage tanks.The major goals of this project include: (1) increasing the energy density of charged electrolytes by varying the composition of iron and titanium water solutions, respectively, for reducing electrolyte transportation costs; and (2) optimizing the cell structure for improved battery performance.
Project Methods
1) Studying electrolyte compositions for achieving higher energy densities of iron-titanium redox flow batteries. We will systematically study the effect of the electrolyte composition on the energy density and power output of an iron-titanium flow battery single cell. The key to improving the energy density of electrolytes is to increase the concentration of iron and titanium salts in aqueous solutions. In these electrolytes, a strong acid like sulfuric acid, or hydrochloric acid is usually employed for enhancing the proton conductivity. These acids also play an important role in dictating the solubility of iron (III)/iron (II) and titanium (III)/titanium (IV) in water. In other words, the pH and counter anions of iron and titanium have strong effects on the water solubility of iron and titanium salts. Temperature is another factor that decides the solubility of metal salts in water. The operation temperature of our iron-titanium batteries is typically at 25 oC, but it could range from -30 oC to 45 oC. Sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, and hydrobromic acid will all be employed in our study. To this end, an aqueous solution of an acid with various concentrations will be systematically examined for its pH values and ion conductivities. Then, the iron or titanium salt will be gradually added to the solution for its maximal solubility under various temperatures. The pH value, ionic conductivity, and metal salt solubility are three key parameters that we will focus on. We also plan to study the mixed acid systems. For example, an aqueous solution of iron (II)/(III) in 2M sulfuric acid and 2M hydrochloric acid. Our detailed study here will help us identify the optimal composition of electrolytes for achieving higher energy density. The cell performance of these aqueous electrolytes will also be subject to a study using our in-house 4 cm2 flow battery system.2) Optimizing the cell configuration to improve its power output Cell configuration has tremendous effects on its performance. In particular,the structure of electrodes like graphite felts or carbon papers, greatly influence the charging and discharging of the battery. If a graphite felt is used as the electrode, the porosity, hydrophilicity, and nitrogen/sulfur/phosphine content play important roles in the cell performance. A redox reaction on the surface of a graphite feltis a three-phase reaction: an iron or titanium cation, carbon felt, and protons in water. Increasing the porosity of a carbon felt will enhance the surface areas that are available for such a redox reaction. The porosity of these materials will be studied by Brunauer-Memmett-Teller (BET) experiments.Other methods to increase the surface areas of the carbon felt will also be examined. For example, the carbon felt can be thermally treated in an oven under either nitrogen or air streams to 800 oC-1,000 oC. Controlled decarbonation can lead to larger pores. Carbon felts can also be treated with hydrogen peroxide in the presence of a catalytic amount of Fe3+. Fenton reaction is well known for generating hydroxides and hydroxyl radicals, all of which can etch the aromatic rings of the carbon felt. In addition, such radicals will insert -OH groups to the carbon felt surfaces--leading to the higher hydrophilicity of the electrode The hydrophilicity/hydrophobicity of a catalytic site of a carbon electrode is of importance to its catalytic activities. Highly charged iron or titanium cations are very hydrophilic and a hydrophilic pocket can better accommodate a metal salt--allowing facile access to the catalytic site by an iron or titanium cation. It was found that thermal treatment and Fenton degradation can also increase the hydrophilicity of the carbon electrode. In addition, CHN combustion elemental analysis will be employed for examining the nitrogen content in these felts. It is hypothesized that the presence of nitrogen-containing functional groups like pyridine in the carbon electrode can increase the hydrophilicity of the electrodes. The grafting of phosphine or nitrogen groups into the surface of a carbon felt will also be examined for increasing the hydrophilicity. This can be achieved, for example, by impregnating the carbon felt with 1M ammonium phosphate. After 24 h, the ammonium phosphate solution will be removed and the resulted carbon material is going to be heated in an oven under nitrogen to 500 oC for 1 h. Such a heat treatment allows the incorporation of nitrogen and phosphine-containing functional groups into the electrode. BET and elemental analysis experiments will then be utilized for measuring the porosity and nitrogen/phosphine contents. If carbon papers are used in the battery, we will conduct a laser perforation experiment to increase the porosity and hydrophilicity. a 40W CO2 laser engraver in our laboratory will be utilized for generating a large number of pores on the carbon electrode. In practice, we found that even for a carbon felt electrode that has numerous macropores, laser perforation still can improve the access of Ti3+/Ti4+ electro-pair to the catalyst and thus improve the performance of the battery. As a result, we plan to systematically change the laser power output, the size of the laser pores, and the distance between pores. All these can be done facilely by controlling the experimental conditions of laser perforation. The performance of different cell configuration will be evaluated in a 4 cm2 battery that can employ iron and titanium redox pairs as electrolytes in cathode and anode, respectively.

Progress 07/01/22 to 02/28/24

Outputs
Target Audience:Research in this project lays a foundation for us to build our first 10 kW/20 kWh system to be integrated with roof-top solar as energy storage. Residential solar installers who recommend and install battery systems to residential consumers will be our customers. There are several reasons that solar installers want to use our iron-titanium batteries, 1) Many solar installers do not have access to lithium-ion batteries at present--because of the supply chain crunches. Tesla and Panasonic batteries are out of order for the next several years. There is a demand competition of using lithium-ion batteries between energy storage and electric vehicles 2) Although some consumers get used to using lithium-ion batteries in their electronic gadgets, solar installers are deeply worried about the fire safety problem of lithium-ion batteries. Our iron-titanium batteries will reduce solar installers' liability. 3) our Fe/Ti flow batteriesaremuch cheaper than Lithium Ion Batteries, which makes end user more willing to install a battery for their solar system. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?We are working with the Illinois Small Business Development Center at SIU to build a tech hub using our technology as a demonstration and training for SIU students or small business startups. How have the results been disseminated to communities of interest?We have been working with the Southern Illinois University Foundation and the School of Business on the possibility of using our technology for their crypto-mining lab. We also talked with Carbondale city council for using our battery as energy storage for the city's solar field. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Proposal task 1: Studying electrolyte compositions for achieving higher energy densities of iron-titanium redox flow batteries We have been focusing on two aspects in this area: A. Systematically investigating a large number of carbonand graphite-based catalysts: Hetero-aromatics were chemically attached to the pores of graphene/carbon clothes, papers, and felts via chemical modifications. The chemical-modified carbon electrodeswere incubated at high temperatures under heteroatom-enriched gas to increase heteroatom content. The performance of all these carbon materials was studied in a 2 cm2 single-cell flow battery cell. Our data shows that the enrichment of heteroatoms and the incorporation of hetero-aromatics into carbon catalysts significantly increased the power output density. The power output density of a single cell with untreated carbon electrodes was 25 mW/cm2 at 100 mA/cm2. The same system with a treated carbon electrode achieved a power density of 61 mW/cm2 at 180 mA/cm2. B. The solubility of titanium and iron salts in various aqueous acidic solutions was investigated. The combination of acids as supporting electrolytes was also investigated. The best performance (80mW/cm2 at 220mA/cm2) was achieved with two combined acids at a certain ratio as supporting electrolytes. Task 2: Optimizing the cell configuration to improve its power output Flow channels play a critical role in the power output density of a flow battery. A metal electrolyte needs to be in contact with a graphite/carbon porous electrode and catalyst to migrate electrons for both the charge and discharge of a battery. Our focus was on the flow pattern design of the bipolar plates to ensuresufficient contact between electrolytes and the catalytic surfaces inside the carbon/graphite pores. We first tested our flow pattern design with a bipolar plate of a small active area of 2cm2. The experimental data proved that our design of a bipolar plate with a cross-section flow pattern improved cell performance significantly. Based on these experiments, we designed inter-digitized flow channels on a much larger scale, wherespecial consideration was given to the flow manifold design tooptimizeshock current and pressure drop andefficiently deliver electrolytes to every channel on the graphite. A prototype of a battery stack was constructed using the inter-digitized flow channel design. Amajor concern when designing the stack was preventing electrolytes from leaking. Various sealantsand gasket materials were investigated for chemical stability and good sealing. We will continue to build a 7kW battery stack in our phase II research.

Publications


    Progress 07/01/22 to 06/30/23

    Outputs
    Target Audience:Research in this project lays afoundation for us to build our first 10 kW/20 kWh system to be integrated with roof-top solar as energy storage. Residential solar installers who recommend and install battery systems to residential consumers will be our customers. There are several reasons that solar installers want to use our iron-titanium batteries, 1) Many solar installers do not have access to lithium-ion batteries at present--because of the supply chain crunches. Tesla and Panasonic batteries are out of order for the next several years. There is a demand competition of using lithium-ion batteries between energy storage and electric vehicles 2) Although some consumers get used to using lithium-ion batteries in their electronic gadgets, solar installers are deeply worried about the fire safety problem of lithium-ion batteries. Our iron-titanium batteries will reduce solar installers' liability. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?We are working with the Illinois Small Business Development Center at SIU to build a tech hub using our technology as a demonstration and training for SIU students or small business startups. How have the results been disseminated to communities of interest?We have been working withthe Southern Illinois University Foundation and the School of Business on the possibility of using our technology for their crypto-mining lab. What do you plan to do during the next reporting period to accomplish the goals?We already reached our goal of improving energy density to 60-75 mW/cm2. Next, we will test the larger-scale interdigitated flow pattern design to improve the specific energy density of the flow battery.

    Impacts
    What was accomplished under these goals? Proposal task 1: Studying electrolyte compositions for achieving higher energy densities of iron-titanium redox flow batteries We have been focusing on two aspects in this area: A.Systematically investigating a large number of carbon and graphite-based catalysts that are key to the performance of the battery. It is well documented in the literature that a higher percentage of heteroatoms like nitrogen and sulfur can improve the hydrophilicity of the catalysts and thus increase the catalytic activities of the carbon materials. To this end, three types of carbon electrodes (carbon cloth, carbon paper, and carbon felt) were incubated at high temperatures under heteroatom-enriched gas to increase heteroatom content on carbon electrodes. In addition, hetero-aromatics were chemically attached to the pores of graphene/carbon clothes, papers, and felts via chemical modifications. Then, the performance of all these carbon materials was studied in a 2 cm2 single-cell flow battery cell. Our data shows that the enrichment of heteroatoms and the incorporation of hetero-aromatics into carbon catalysts significantly increased the power output density. The power output density of asingle cell with untreated carbon electrodes was 25 mW/cm2 at 100 mA/cm2, while the same system with a treated carbon electrode was able to achieve a power density of 61 mW/cm2 at 180 mA/cm2. B.The solubility of titanium and iron salts in various aqueous acidic solutions was investigated. The combination of acids as supporting electrolytes was also investigated. The best performance (80mW/cm2 at 220mA/cm2) was achieved with two combined acids at a certain ratio as supporting electrolytes. Task 2: Optimizing the cell configuration to improve its power output Flow channels play a critical role in the power output density of a flow battery. A metal electrolyte needs to be in contact with a graphite/carbon porous electrolyte to migrate electrons for both the charge and discharge of a battery. Insufficient contact between electrolytes and the catalytic surfaces inside the carbon/graphite pores will lead to lower battery power densities. Our focus was on the flow pattern design of the bipolar plates. We first tested our flow pattern design with a bipolar plate of a small active area of 2cm2. The experimental data proved that our design of a bipolar plate with a cross-section flow pattern improved cell performance significantly. Based on these experiments, we designed inter-digitized flow channels on a much larger scale (12 inches by 12 inches). We are currently in the process of testing these larger-scale cells.

    Publications