It has become increasing clear that renewable electricity can be generated on a large scale through a variety of different methods. While this progress has begun to decarbonize baseload electricity generation, the intermittent nature of the required resources has proven difficult to incorporate into regional electrical grids. Grid-scale electricity storage methods are a promising solution to the inefficiencies associated with unpredictable electricity generation. Redox flow batteries have demonstrated the ability to be used as a reasonably low-cost, long-term electrical storage method. Specifically, vanadium redox flow batteries (VRBs) have been of special interest due to their chemical stability, long life cyclability, and potential for high capacity electrical storage. One of the main factors limiting market penetration of redox flow batteries in energy storage portfolios is the high capital cost associated with this comparatively low energy density technology. To this end, many current research efforts focus on improving the energy density of VRBs to warrant this cost in the long term.

This work focuses on improving the energy density of VRBs by probing the effects of a variety of different metal electrocatalysts. This process uses metal salts to form catalytically active nanoparticles on the surface of the anode to improve the kinetics of the anodic reaction in the VRB. The systems of interest in this study involved using tin, copper, and lead metals deposited on the surface of the anode using a variety of techniques. The direct reduction of metal salts results in the formation of nano-scale and micron-scale electroplated particles on the surface of the anode, which can be used to improve the kinetics of the sluggish anodic reaction in VRBs. This work shows that when as little as 0.02 M concentrations of tin chloride are added to 1.0 M vanadium electrolyte, electrochemically reduced tin nanoparticles have excellent catalytic properties toward the anodic reaction, improving current densities by over 30% and improving the overall capacity of the battery. There were also some synergistic effects observed when the tin salts were coupled with copper salts, further improving the capacity of the battery. A series of methods were used to probe the effects of synthesized lead particles as well. We will present how these processes can have a dramatic effect on increasing both capacity and energy density of aqueous vanadium redox flow batteries.