With the cost of renewable energy near parity with fossil fuels, energy storage is paramount. We report a breakthrough on a bioinspired NRFB active-material, with greatly improved solubility, and place it in a predictive theoretical framework.

A promising nonaqueous redox flow battery electrolyte has been developed by leveraging natural selection to elucidate stable, redox-active molecules.

Durable and efficient energy storage is a critical aspect of modern electrical grids, especially those comprising energy from intermittent and renewable sources. Non-aqueous redox flow batteries (NRFB) are a promising technology to meet this growing need, with the potential to greatly exceed the energy density of their aqueous counterparts while maintaining key advantages over Li-ion batteries. These advantages include decoupled power and energy ratings, thermal stability and the capability of long-duration storage. Notwithstanding these promising attributes, the development of NRFB has been severely hampered by chemical instability of active materials charged and/or discharged states. Herein we demonstrate the excellent electrochemical stability of a recently reported NRFB active material, vanadium(iv/v)bis-hydroxyiminodiacetate (VBH) using operando spectroscopic measurements. This technique shows tight coupling between changes in the concentrations of the vanadium(iv) and vanadium(v) ions and the applied current. This direct measurement of electrochemical stability is widely available, and its routine use to characterize potential redox active species during cycling, verifying a clean transition between redox states, would be of great value to the NRFB community. Further, we report a method of large-scale preparation of VBH that makes use of inexpensive chemical feedstocks, overcoming another important obstacle to its implantation in an NRFB system.

Solutions of the bi-harmonic equation valid in the region bounded externally by parallel lines and internally by a circle midway between the lines have been given by one of the Authors in a recent paper [2]. These solutions were adapted to the requirements of certain problems in the theory of elasticity, but modified solutions satisfying the boundary conditions characteristic of viscous fluid motion are easily derived. These modified solutions will here be given and will be used to find the stream function corresponding to the slow rotation of a cylinder placed symmetrically between parallel walls.