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Innovative Approach to Enhance Battery-Based Seawater Desalination

Engineering advancements have paved the way for eliminating the problematic fluid flow “dead zones” common in electrodes utilized for battery-driven seawater desalination. The newly developed method employs a tapered flow channel design that facilitates rapid and efficient fluid movement, potentially allowing for reduced energy consumption compared to traditional reverse osmosis methods.

Challenges related to technology have hindered the widespread adoption of desalination processes. The predominant desalination technique, reverse osmosis, involves pushing water through a semipermeable membrane to extract salt, which can be both costly and energy-intensive. In contrast, the battery-based approach employs electricity to remove charged salt ions from water. However, this method also necessitates energy input to propel water through electrodes featuring small, irregularly shaped pores.

“Conventional electrodes require energy to facilitate fluid movement due to the absence of inherently structured flow channels,” explained Kyle Smith, a mechanical science and engineering professor at the University of Illinois Urbana-Champaign and principal investigator of the study. “By integrating channels within the electrodes, this innovative technique may reduce the energy needed for water circulation, potentially surpassing the efficiency of current reverse osmosis systems.”

Smith’s research on battery-based desalination has evolved over several years of modeling and experimentation, culminating in a recent study that showcases the inaugural application of electrodes featuring microchannels known as interdigitated flow fields (IDFFs).

The recent investigation further enhances IDFFs by adopting a tapered channel design, which has shown to increase fluid flow—also referred to as permeability—by two to three times compared to straight channels. The study’s findings were published in the journal Electrochimica Acta.

“Our initial investigations into straight channels revealed the presence of dead zones within the electrodes, characterized by pressure drops and uneven flow distribution,” stated Habib Rahman, a graduate student at Illinois involved in the study. “In addressing this issue, we developed a library of 28 varied straight channel designs to analyze conductance and flow discrepancies, eventually leading to the implementation of our tapered channel technique.”

Throughout their experimentation, Smith and Rahman encountered manufacturing hurdles, particularly concerning the duration required to mill channels into the electrodes. This aspect poses a significant challenge for potential large-scale production. Nevertheless, Smith expressed optimism about overcoming these obstacles.

“In addition to its potential benefits for electrochemical desalination, our channel-tapering theory and the design principles we established can be directly applied to a variety of other electrochemical devices that utilize flowing fluids,” Smith emphasized. “This includes technologies for energy storage and conversion, environmental sustainability initiatives such as fuel cells, electrolysis cells, flow batteries, carbon capture systems, and lithium extraction devices. Unlike previous channel-tapering methods that relied on makeshift designs, our approach offers physics-based guidelines to ensure consistent flow and reduce pressure drops simultaneously.”

This research was supported by the Office of Naval Research. Smith, Rahman, and co-authors Irwin Loud IV, Vu Do, and Abdul Hamid currently hold pending patents associated with their findings under U.S. patent applications 17/980,017, 17/980,023, and 63/743,995.

Smith is also associated with the fields of material science and engineering, as well as the Beckman Institute for Advanced Science and Technology.

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