We will discuss the impact of backbone and particle structure on the charge transport and chemical stability of novel soluble redox-active polymers used for energy storage in non-aqueous redox flow batteries (NRFBs). This technology promises efficient grid-scale energy storage due to the straightforward scalability, ample choice for active materials, and higher energy densities compared to aqueous systems. We recently introduced a macromolecular approach based on size-exclusion on nanoporous membranes for overcoming sample crossover and high area-specific resistance in organic solvents. The storage media, redox-acvie polymers (RAPs) or redox-active colloids (RACs) consist of particles made with an insulating backbone decorated with a variety of redox pendants, including anolytes such as viologen and, more recently, catholytes such as the cyclopropenium ion. Applications for NRFBs require efficient inter-pendant charge transfer, chemical reversibility, and high energy density (high solubility and high reaction potentials). Electrochemical evaluation using a variety of advanced design and electroanalytical methods, such as DFT modeling, capacity and rate analysis, and nano bulk electrolysis on single polymer particles has helped us elucidate powerful strategies for improving the electrochemical performance of our batteries. In a first study, we will describe how single-particle interrogation allows us to better understand rate and electrolysis parameters of viologen RACs made of particles of hundreds of nm in size. On a second study, we will describe how backbone structure impacts the chemical stability of cyclopropenium RAPs. Our computational and experimental results indicate that electronic interaction between the redox pendant and backbone dramatically impacts chemical stability under continued cycling.The impact of RAP and RAC structure on the performance of full size-exclusion electrochemical cells using nanoporous separators will be described. These experiments illuminate new directions in the design and testing of these intriguing polymers for next-generation energy storage.

Impact of backbone structure and particle morphology on the electrochemical performance of soluble redox-active polymers

256th National Meeting (2018)

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