Engineers at the University of Illinois Urbana-Champaign have developed a novel approach that could revolutionize the field of battery-based seawater desalination by addressing a longstanding technical challenge: fluid flow “dead zones” within desalination electrodes. By designing a more efficient and effective method for moving fluids through the electrodes, this innovative technique offers the potential for lower energy requirements compared to conventional seawater desalination methods, such as reverse osmosis.
Reverse osmosis (RO) has been the dominant desalination technology for years, successfully providing freshwater by forcing seawater through a semi-permeable membrane that blocks salts, but it has a key drawback: it’s both expensive and energy-intensive. In comparison, battery-based desalination is a more energy-efficient process that uses electrical currents to remove charged salt ions from water. However, it faces challenges in its current form due to the need to push water through electrodes that contain irregular and poorly structured pores.
Traditional Electrode Problems and the Need for Change
As Kyle Smith, a mechanical science and engineering professor at the University of Illinois and leader of the research, explains, “Traditional electrodes still require energy to pump fluids through because they do not contain any inherently structured flow channels.” These electrodes, in which water flows through small, irregularly shaped pores, often generate “dead zones.” These dead zones are areas where fluid flow stagnates, leading to pressure drops and uneven flow distribution. This inefficient fluid dynamics means more energy is needed to move water through the system.
To overcome these challenges, Smith and his research team have focused on integrating physics-based, engineered flow structures within the desalination electrodes. The new design involves creating microchannels within the electrode structure, which mimics more organized flow paths, potentially allowing fluids to move through much more efficiently, and ultimately reducing the amount of energy required to desalinate seawater.
The Innovative Channel-Tapering Design
In their latest study, published in the Electrochimica Acta journal, Smith’s group expanded upon previous work by incorporating “interdigitated flow fields” (IDFFs) in desalination electrodes—microscopic channels designed to optimize fluid flow. The new twist on this approach, however, lies in the shape of the channels themselves. Unlike traditional straight channels, which were the focus of earlier research, these new channels are tapered—narrowing gradually as the fluid travels through them.
This tapered design dramatically enhances fluid permeability, improving flow efficiency by two to three times compared to straight channels. “Our initial work on straight channels in electrodes led us to discover dead zones within the electrodes where we saw pressure drops and nonuniform flow distribution,” said Habib Rahman, a graduate student working on the project. In response to this, the team tested and refined 28 different straight channel variations to understand how variations in channel structure affected fluid conductance and distribution.
The breakthrough came when the team applied tapered channels to the electrodes, which allowed water to flow more smoothly and evenly through the electrode’s microscopic channels. By carefully designing these tapered flow paths, the engineers succeeded in minimizing pressure drops while simultaneously promoting uniform flow throughout the system. The result: better energy efficiency, with potentially less power needed to desalinate the same volume of water.
Challenges in Manufacturing and Scalability
Despite these promising results, the research team encountered several manufacturing challenges during their experiments. Milling such small, intricate flow channels into the electrodes is a time-consuming process. Scaling up this fabrication technique to industrial levels for use in large-scale desalination plants would require addressing the time and costs involved in producing these finely engineered electrodes.
However, Smith is optimistic about overcoming this obstacle. “While there are some manufacturing challenges associated with milling these microchannels—especially on a larger scale—we’re confident that there are ways to streamline production without sacrificing the efficiency benefits we’ve uncovered,” he said. The research team believes that improvements in manufacturing techniques will be able to keep pace with their design innovations, making it possible to implement their method at a commercial scale.
Broader Applications for Electrochemical Devices
While this groundbreaking technique was developed to address the fluid flow challenges in battery-based desalination electrodes, its potential applications extend far beyond the realm of desalination. As Smith points out, “Our channel-tapering theory and associated design principles can be applied directly to any other electrochemical device that uses flowing fluids, including those for energy storage conversion and environmental sustainability like fuel cells, electrolysis cells, flow batteries, carbon capture devices, and lithium recovery devices.”
Essentially, the principles developed in this study are versatile enough to improve the performance of a wide range of electrochemical systems that rely on the flow of liquids or gases. This includes energy applications such as hydrogen production through electrolysis or the efficient storage and conversion of energy in advanced batteries. It may also be crucial for environmental technologies like carbon capture, where optimizing fluid flow is key to improving performance and minimizing energy use.
Designing for Efficiency: A Physics-Based Approach
One of the main innovations in this new method is the physics-based design behind the tapered channels. While previous efforts at channel-tapering sometimes led to impromptu or “trial-and-error” approaches, this technique is built on a solid scientific foundation. The researchers have established clear design guidelines that take into account the principles of fluid dynamics to create not only smooth, well-distributed flow paths but also uniform pressure profiles within the electrodes. By designing for both uniform flow and minimized pressure losses, Smith’s team has made a significant step toward improving the overall energy efficiency of electrochemical desalination systems and other related technologies.
This is a far cry from prior ad-hoc strategies, which lacked clear scientific frameworks for channel shaping, often resulting in inconsistent outcomes. By moving beyond mere trial and error, this research establishes a reproducible methodology for building more efficient electrochemical systems, with widespread potential across many different fields.
Conclusion: A Step Toward Sustainable Desalination
This breakthrough in battery-based desalination provides a promising alternative to traditional, energy-hungry methods of desalting seawater. The incorporation of tapered channels into desalination electrodes presents a way to reduce energy consumption and enhance fluid flow efficiency, ultimately leading to a more sustainable, cost-effective way to address the global freshwater shortage. As these techniques become refined, and as manufacturing hurdles are cleared, the potential for large-scale adoption grows, which could help alleviate water scarcity around the world.
In a broader context, the innovative ideas and techniques emerging from this study are poised to benefit a variety of electrochemical technologies, from energy storage to environmental sustainability. By applying physics-driven principles to enhance fluid dynamics in such systems, engineers are bringing us closer to a future where clean energy and water solutions can work in tandem to create a more sustainable world.
Reference: Md Habibur Rahman et al, Tapered, Interdigitated Channels for Uniform, Low-Pressure Flow through Porous Electrodes for Desalination and Beyond, Electrochimica Acta (2025). DOI: 10.1016/j.electacta.2024.145632