Protocol for Evaluating Anion Exchange Membranes for Nonaqueous Redox Flow Batteries.

Nonaqueous redox flow batteries often suffer from reduced battery lifetime and decreased coulombic efficiency due to crossover of the redox-active species through the membrane. One method to mitigate this undesired crossover is to judiciously choose a membrane based on several criteria: swelling and structural integrity, size and charge of redox active species, and ionic conductivity. Most research to date has focused on reducing crossover by synthesizing modified redox-active molecules and/or new membranes.

Zinc-Catalyzed Two-Electron Nickel(IV/II) Redox Couple for Multi-Electron Storage in Redox Flow Batteries.

Energy storage is a vital aspect for the successful implementation of renewable energy resources on a global scale. Herein, we investigated the redox cycle of nickel(II) bis(diethyldithiocarbamate), Ni(dtc), for potential use as a multielectron storage catholyte in nonaqueous redox flow batteries (RFBs). Previous studies have shown that the unique redox cycle of Ni(dtc) offers 2e chemistry upon oxidation from Ni → Ni but 1e chemistry upon reduction from Ni → Ni → Ni.

Controlling One-Electron vs Two-Electron Pathways in the Multi-Electron Redox Cycle of Nickel Diethyldithiocarbamate.

The unique redox cycle of Ni(dtc), where dtc is ,-diethyldithiocarbamate, in acetonitrile displays 2e redox chemistry upon oxidation from Ni(dtc) → [Ni(dtc)] but 1e redox chemistry upon reduction from [Ni(dtc)] → Ni(dtc) → Ni(dtc). The underlying reasons for this cycle lie in the structural changes that occur between four-coordinate Ni(dtc) and six-coordinate [Ni(dtc)]. Cyclic voltammetry (CV) experiments show that these 1e and 2e pathways can be controlled by the addition of pyridine-based ligands (L) to the electrolyte solution.

Synthesis, characterization, and electrocatalytic activity of bis(pyridylimino)isoindoline Cu(II) and Ni(II) complexes.

Two NNN pincer complexes of Cu(ii) and Ni(ii) with BPIMe- [BPIMe- = 1,3-bis((6-methylpyridin-2-yl)imino)isoindolin-2-ide] have been prepared and characterized structurally, spectroscopically, and electrochemically. The single crystal structures of the two complexes confirmed their distorted trigonal bipyramidal geometry attained by three equatorial N-atoms from the ligand and two axially positioned water molecules to give [Cu(BPIMe)(H2O)2]ClO4 and [Ni(BPIMe)(H2O)2]ClO4. Electrochemical studies of Cu(ii) and Ni(ii) complexes have been performed in acetonitrile to identify metal-based and ligand-based redox activity.