Person: Valle, Alvaro
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Valle
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Alvaro
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Valle, Alvaro
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Publication Alkaline quinone flow battery(American Association for the Advancement of Science (AAAS), 2015) Lin, Kaixiang; Chen, Qing; Gerhardt, Michael; Tong, Liuchuan; Kim, Sang Bok; Eisenach, Louise; Valle, Alvaro; Hardee, D.; Gordon, Roy; Aziz, Michael; Marshak, MichaelStorage of photovoltaic and wind electricity in batteries could solve the mismatch problem between the intermittent supply of these renewable resources and variable demand. Flow batteries permit more economical long-duration discharge than solid-electrode batteries by using liquid electrolytes stored outside of the battery. We report an alkaline flow battery based on redox-active organic molecules that are composed entirely of Earth-abundant elements and are nontoxic, nonflammable, and safe for use in residential and commercial environments. The battery operates efficiently with high power density near room temperature. These results demonstrate the stability and performance of redox-active organic molecules in alkaline flow batteries, potentially enabling cost-effective stationary storage of renewable energy.Publication A redox-flow battery with an alloxazine-based organic electrolyte(Springer Nature, 2016) Lin, Kaixiang; Gómez-Bombarelli, Rafael; Beh, Eugene; Tong, Liuchuan; Chen, Qing; Valle, Alvaro; Aspuru-Guzik, Alan; Aziz, Michael; Gordon, RoyRedox-flow batteries (RFBs) can store large amounts of electrical energy from variable sources, such as solar and wind. Recently, redox-active organic molecules in aqueous RFBs have drawn substantial attention due to their rapid kinetics and low membrane crossover rates. Drawing inspiration from nature, here we report a high-performance aqueous RFB utilizing an organic redox compound, alloxazine, which is a tautomer of the isoalloxazine backbone of vitamin B2. It can be synthesized in high yield at room temperature by single-step coupling of inexpensive o-phenylenediamine derivatives and alloxan. The highly alkaline-soluble alloxazine 7/8-carboxylic acid produces a RFB exhibiting open-circuit voltage approaching 1.2 V and current efficiency and capacity retention exceeding 99.7% and 99.98% per cycle, respectively. Theoretical studies indicate that structural modification of alloxazine with electron-donating groups should allow further increases in battery voltage. As an aza-aromatic molecule that undergoes reversible redox cycling in aqueous electrolyte, alloxazine represents a class of radical-free redox-active organics for use in large-scale energy storage.Publication High-performance Aqueous Redox Flow Battery (ARFB)(2015) Lin, Kaixiang; Chen, Qing; Eisenach, Louise; Valle, Alvaro; Gordon, Roy; Aziz, Michael; Marshak, Michael