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

Energy storage is a vital aspect for the successful implementation of renewable energy resources on global scale. Herein, we investigated redox cycle nickel dithiocarbamates potential use as catholytes in non-aqueous flow batteries. The unique (Ni(dtc)2) offers ability to better understand these reactions by displaying 2e- chemistry upon oxidation from Ni(II) → Ni(IV) but 1e- reduction Ni(III) Ni(II). underlying reasons this lie structural changes that occur between four-coordinate Ni(dtc)2 and six-coordinate [Ni(dtc)3]+. Cyclic voltammetry spectroscopic experiments show pathways can be controlled addition ancillary ligands such pyridine derivatives Lewis acids Zn(II). Specifically, different based N-donor (L) electrolyte solution results producing mixture five-coordinate [Ni(dtc)2L]+ [Ni(dtc)2(L)2]+ intermediate species which decay [Ni(dtc)3]+ parallel pathways. equilibrium constants L coordination were determined found increase with larger pKa values base. On side, Zn(II) shown consolidate two peaks into single where reduced directly Ni(dtc)2. This enhancement believed due chemical assistance removing dtc- ligand Ni(dtc)3 intermediate, allowing easier Around 80% columbic efficiency obtained when was used catholyte chrono potentiometric (CP) H cell experiment presence 24 mM Zn2+ ion.