Exploring Particle Dispersion and Charge Percolation in Suspension Electrodes: Bridging Electrochemical Performance and Rheology

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Growing concerns over sustainable energy sources and access to clean water have prompted the need for development of efficient and cost-effective technologies that can be readily scaled to meet the increasing demand. Among the recent advances, the concept of flowable suspension electrodes has emerged as a highly promising approach for addressing the challenges in large-scale energy storage and water purification. Suspension electrodes can be broadly defined as a slurry of electrochemically active materials suspended in a liquid electrolyte. Performance of these electrodes is governed by the flow conditions and the system design, making them significantly more challenging to characterize than conventional electrodes. This project is designed to address some of the open questions related to the electrochemical performance and the flow characteristics of these electrodes to help determine optimal engineering design choices for this new class of electrodes. Accordingly, a number of studies will be conducted to explore and reveal the complex relation between the flowability and the electrochemical performance of these electrodes. The resulting discoveries and new knowledge gained from these studies will benefit research on emerging energy storage and water treatment technologies and help develop new scalable technologies that utilize this new class of electrodes. This project will also offer significant opportunities to extend and amplify the impact of the research to a larger society. It will target energy-themed activities and help enhance the education of a broad range of students, attracting young talented people to STEM careers in the areas of strategic national interests.Suspension electrodes rely on volume-spanning networks of conducting particles to effectively facilitate charge transport and minimize ohmic losses. Such particle networks are expected to have a minimum impact on the viscosity of the electrode so that the energy losses incurred by pumping can be minimized during operation. This trade-off between the electrical conductivity and the viscosity imposes critical design limitations; therefore, the most rational path forward to improve the performance metrics of these flowable electrodes is to explore ways to design suspensions that have the desired electrochemical properties with matching rheological characteristics. Motivated by this need, the objective of this project is to establish a new physics-based framework for rational design of high-performance suspension electrodes with optimized particle networks that enable enhanced flowability and facile charge transport. Toward this goal, a key objective of this work will be to quantify the critical tunable parameters that govern particle interactions, particle clustering, and the evolution of percolation networks for charge transport in these electrodes. This understanding will enable direct control of the particle networks and offer a certain level of tunability of the key properties to arrive at the optimal engineering design choices. A set of hypothesis-driven studies will be conducted to provide new insights into materials, processing, particle interaction, charge transfer, and percolation processes in these electrodes. It is anticipated that these studies will help expand the knowledge in colloidal science by investigating a unique class of suspensions for a broader research community. Findings of this study are also expected to aid in the design of functional inks for a variety of applications. The resulting discoveries and new knowledge gained from this work will also benefit research on emerging water desalination technologies and help formulate optimized suspensions for these applications.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.