(326l) Establishing Design Principles for Electrochemical Systems with Flowable Suspension-Based Electrolytes

Electrochemical systems with flowable suspension-based electrolytes have the potential to further decarbonization efforts by offsetting the intermittency of electricity generation from renewable energy sources, reducing the carbon footprint of synthetic processing for the fuel and chemical production (e.g., hydrogen, cement, steel), and supporting novel approaches to resource management in furtherance of a circular economy. In such systems, suspension-based electrolytes – nano- to micro-sized active and/or conductive particles dispersed in aqueous or nonaqueous solvents – are transported through electrolytic, galvanic, or bidirectional electrochemical reactors. The attractive interactions between the particles of the flowing electrolyte enable the formation of dynamic percolated particle-networks allowing charge conduction across the entire reaction volume. Suspensions can be designed to incorporate a diverse array of electrochemical reactions including intercalation into solid materials, electrodeposition onto high surface area particles, and solution-phase reactions. However, the complex interplay between rheology, electrochemistry and transport in these flowable suspension-based electrolytes is poorly understood and challenging experimental design and operation of high-performance electrochemical devices^[1-4].

Here, we present a one-dimensional model via integrating the electrochemistry, transport and non-Newtonian rheology to develop design principles for electrochemical cells with flowable suspension-based electrolytes^[5]. Reaction kinetics at the particle interfaces, flow-dependent charge transport models, mass transport descriptions across the boundary layers of the suspended particles, and non-Newtonian rheological models are combined to form a compact set of governing equations. We discuss key dimensionless groups whose relative magnitudes determine the impact of different physical processes on cell behavior. Using this framework, we explore different dynamic and geometric constraints to identify operating regimes, to compute tradeoffs between cell power output and suspension pumping power input, and, ultimately, to describe favorable materials sets, operating envelopes and cell geometries that enable desirable performance. The results presented here will help in establishing a general modeling framework and design rules for electrochemical systems that use flowable suspension-based electrolytes with applications in a number of current and emerging areas in energy and sustainability.

Acknowledgement

This work was funded by the Skoltech – MIT Next Generation Program.

References

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