Biological nicotinamide cofactor as a redox-active motif for reversible electrochemical energy storage

Nicotinamide adenine dinucleotide (NAD${}^{+}$) is one of the most well-known redox cofactors carrying electrons. Now, it is reported that the intrinsically charged NAD${}^{+}$ motif can serve as an active electrode in electrochemical lithium cells. By anchoring the NAD${}^{+}$ motif by the anion incorporation, redox activity of the NAD${}^{+}$ is successfully implemented in conventional batteries, exhibiting the average voltage of 2.3 V. The operating voltage and capacity are tunable by altering the anchoring anion species without modifying the redox center itself. This work not only demonstrates the redox capability of NAD${}^{+}$, but also suggests that anchoring the charged molecules with anion incorporation is a viable new approach to exploit various charged biological cofactors in rechargeable battery systems. (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)