A Neutral pH Aqueous Organic-Organometallic Redox Flow Battery with Extremely High Capacity Retention

作者：Beh, Eugene S.; De Porcellinis, Diana; Gracia, Rebecca L.; Xia, Kay T.; Gordon, Roy G.^*; Aziz, Michael J.^*

来源：ACS Energy Letters, 2017, 2(3): 639-644.

DOI：10.1021/acsenergylett.7b00019

• ELECTRICAL ENERGY-STORAGE
• COUPLES
• SAFE

We demonstrate an aqueous organic and organometallic redox flow battery utilizing reactants composed of only earth-abundant elements and operating at neutral pH. The positive electrolyte contains bis((3-trimethylammonio)propyl)ferrocene dichloride, and the negative electrolyte contains bis(3-trimethylammonio)propyl viologen tetrachloride; these are separated by an anion-conducting membrane passing chloride ions. Bis(trimethylammoniopropyl) functionalization leads to similar to 2 M solubility for both reactants, suppresses higher-order chemical decomposition pathways, and reduces reactant crossover rates through the membrane. Unprecedented cycling stability was achieved with capacity retention of 99.9943%/cycle and 99.90%/day at a 1.3 M reactant concentration, increasing to 99.9989%/cycle and 99.967%/day at 0.75-1.00 M; these represent the highest capacity retention rates reported to date versus time and versus cycle number. We discuss opportunities for future performance improvement, including chemical modification of a ferrocene center and reducing the membrane resistance without unacceptable increases in reactant crossover. This approach may provide the decadal lifetimes that enable organic organometallic redox flow batteries to be cost-effective for grid-scale electricity storage, thereby enabling massive penetration of intermittent renewable electricity.

• 出版日期2017-3