Redox flow batteries (RFBs) have increasingly being recognized as a prominent candidate for large-scale energy storage due to their unique advantages of high safety, decoupling of power and energy, long lifespan, quick response, and potentially low cost. Electrolyte is de facto the most critical component in a RFB system. This presentation describes development of new electrolyte chemistries at Pacific Northwest National Laboratory. Solvation chemistry of the different electrolyte systems will be discussed, which provide a greater understanding of dynamic interactions between solvent-solvent, ion-solvent, and ion-ion at the molecular level. Such understanding is pivotal in developing new redox flow system with higher energy density and temperature stability. A new RFB based hydrogen generation technology will also be presented.