Cyanopyridines As Extremely Low-Reduction-Potential Anolytes for Nonaqueous Redox Flow Batteries

The reversible reduction of 3-cyano-4-methyl-6-(3,5-dimethylphenyl)pyridine to its radical anion at -2.50 V vs Fc+/0 (top), and its capacity retention and coulombic efficiency over 100 charge-discharge cycles (bottom).

Scientific Achievement

Discovery of a cyanophenylpyridine derivative with a very low reduction potential and good stability during cycling.

Significance and Impact

Nonaqueous solvents have a much larger electrochemical window than aqueous systems, and practically viable nonaqueous redox flow batteries will require redox-active molecules that utilize that window, as this optimized cyanophenylpyridine derivative does.

Research Details

  • The three cyanopyridine isomers and all 10 cyanophenylpyridine isomers were examined computationally and experimentally, where reduction potentials, propensity for dimerization of the radical anion, and cycling stability were determined.
  • The 3-cyano-6-phenylpyridine isomer with three strategically placed methyl groups had a very low reduction potential, good cycling stability, and a radical anion with a little propensity for dimerization.

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DOI: 10.1002/chem.202200149

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