Fossil fuel depletion, a harmful effect of greenhouse gas emission and future energy demand, requires an essential transition from hydrocarbon fuel to renewable and environmentally friendly energy sources. Solar and wind energy are the most abundant and accessible renewable energy, however, they are not available all the time. Environmental factors such as bad weather, intermittent, variable, and diffuse natures make renewable energy unavailable. Deployment of renewable energy as the main energy source in power grids requires low-cost, scalable energy storage. Energy storage is a vital part of successful renewable energy implementation. Redox flow batteries are promising to fulfill all of these requirements. Vanadium-based aqueous redox flow batteries (ARFBs) are one of the primary responses to the grid-level energy storages. However, ARFBs suffer from numerous drawbacks, e.g., low energy density (∼50 W•h L -1 ), limited operational temperatures (0-100 °C), and a narrow electrochemical window (1.23 V). To overcome those limitations, non-aqueous redox flow batteries were introduced to the energy storage community. A simple schematic diagram of NARFBs is shown in Figure . In charge mode, the catholyte oxidizes while the anolyte reduces and in discharge mode, the opposite reaction occurs. Anolyte and catholyte continuously flow to the fuel cell by the pump. Anolyte and catholyte tanks can be scaled upon demand. >10000 cycles) remain a challenge. Recently many people are focusing on organic analytes, catholyte-based NARFBs. But inorganic metal complex anolyte and catholyte are more stable in terms of longevity. Different metals like V, Cr, Mn, Co, Cu, and Ni complexes bearing acetylacetonate (acac), dithiolate, dithiolene, 2,2′-bipyridine (bpy), and cyclopentadienyl ligands have lately gained attention as electrolytes for NRFBs. To increase the number of electrons stored per molecule, most of the studies have focused on the two 1e -redox couples. Some Ni and thiocarbamate-based complexes also showed a good possibility in NARFBs.