Redox flow batteries
In order to mitigate the global impact of climate change, renewable energies (wind and solar) are on track to overtake fossil fuels as our dominant energy source in the near future. Current research in the Holubowitch Lab focuses on developing next-generation flow batteries with active species based on earth-abundant elements (C, H, N, O, S, Fe) for storing and delivering intermittent wind and solar energy when the wind doesn't blow and the sun doesn't shine. We aim to engineer high energy density electrolytes using low-cost additives or solid boosters. We are also exploring the mechanisms that lead to long-term battery degradation. Electrochemical sensors for energetic compounds There is a critical need for reliable, inexpensive sensors for explosive compounds in the context of homeland security and isolation of environmental contamination. Insolubility, extremely low vapor pressures, and inherent explosivity pose significant challenges for conventional detection protocols. In this project we investigated the spectroelectrochemistry of various explosive compounds dissolved in an organic solvent (acetonitrile) in the presence and absence of dissolved oxygen. Dissolved oxygen plays an important role in the electro-reduction of these species during sensing that could be exploited by future (electro-)chemical sensors. Capacitive deionization for water desalination Capacitive deionization (CDI) is an emerging low-cost water treatment technology that is best suited for “polishing” brackish or fresh water to ultra-low salt concentrations (conductivity) for a variety of uses. Our work investigated the interfacial chemistry of activated carbon cloths with high specific surface areas for electrosorption. We studied morphological changes in carbon cloth fibers over long-term deionization experiments. SEM analysis revealed pitting and cracking in the fibers that was correlated to carbon/oxygen ratios and sheet resistance of the cloths before and after cycling. These results yielded unprecedented potential mapping of faradaic and capacitive processes that occur during CDI. In a spinoff project, we repurposed membrane-free CDI cells to intentionally remove dissolved oxygen from solution in-line with a desalination cell. After passing through the deoxygenation cell, efficiency of the subsequent desalination cell dramatically improves. Thermal energy harvesting An earlier project sought to develop thermoelectrochemical cells (thermocells) for converting the low-grade waste heat that is ubiquitous in modern society (transportation, industry, HVAC, etc.) into usable electricity. We engineered efficient thermal properties in prototype devices utilizing the common ferro/ferri-cyanide redox couple due to its low-cost and high Seebeck coefficient (1.4 mV/K). We synthesized low-cost, high-surface area carbon nanotube-based composite electrodes to maximize current output from these inherently low-efficiency devices. The results were benchmarked against an all-CNT buckypaper sheet electrode material, which left substantially more active area inaccessible along with poorer current collector adhesion in comparison to our spray-coated composite. Other previous projects: Liquid metal batteries Direct methanol fuel cells |