Next Generation Materials and Strategies for the Advancement of Redox-Flow Batteries

Thesis (Ph.D.)--University of Washington, 2021Initiatives to increase the capacity of renewable energy into our electrical grid have grown substantially over the last decade in efforts to reduce global carbon emissions. The COVID-19 pandemic saw an unprecedented decline in demand for fossil fuels, while demand for renewables surged. Despite this temporary curb in carbon emissions, they have rebounded strongly as the economy begins to recover. Demand for renewables will continue to increase as a result, yet the inherent intermittency of this energy source poses a challenge for meeting this demand. The use of batteries as electrochemical energy storage devices has shown promise for solving this issue, reversibly converting electrical energy into chemical energy to smooth out the intermittency of renewables. One type of battery, Redox-flow batteries (RFBs), have become particularly attractive due to their unique aspect of separating the power and energy from the system. This allows for flexibility in terms of scaling and sizing. Despite this advantage, the high cost of the materials forthis technology has limited its commercialization. This dissertation will discuss research efforts to develop higher performing, cost effective, and sustainable alternative materials necessary for the commercial penetration of RFBs. Early work in developing low-cost sol-gel ceramic membranes will be addressed, which resulted in a patent outlining a development process which reduced the cost by almost 10x compared to the industry standard for RFBs. Next, research focusing on the use of redox-active organic materials as a cost effective and environmentally sustainable alternative to the current metal-ion based RFBs is presented, where derivatives of the fluorenone molecule, a common abundant precursor in organic synthesis and pharmaceuticals, were demonstrated for use in an aqueous RFB. Finally, efforts to incorporate deep-eutectic solvent electrolytes into organic based RFBs will be highlighted, giving an overview of the high-throughput and data-driven strategies necessary to probe the immense design space for these materials