Abstract
Freshwater, a resource critical to social and economic stability, can become temporarily inaccessible after natural disasters such as earthquakes and hurricanes. Transport of water to remote areas during emergencies is expensive and potentially dangerous. Production of fresh water from local brackish and saline resources requires compact, mobile and energy-efficient devices. Reverse-osmosis (RO) uses high-pressure pumps that make down-sizing to mobile scales challenging, while an alternative to RO, capacitive deionization (CDI) based on low-density, low-capacity carbon electrodes, necessitates large footprint devices that are better suited for stationary desalination. Faradaic deionization (FDI) based on the silver–silver chloride conversion reaction provides high-capacity desalination in smaller formfactors. The silver electrode, with a theoretical capacity of 238 mAh/g, is used to remove chloride ions but the low-dimensional architectures of sheet and mesh electrodes limit material utilization. We have developed architected silver and silver chloride sponges that demonstrate high salt removal capacity (80 mg/g, 68 mg/cm2) owing to their high-surface area porous structure. The three-dimensionally interconnected silver network facilitates electronic and ionic transport throughout the bulk of the sponge, enabling scaling to millimeters-thick electrodes. We investigate the design of compact multi-channel flow-cell devices using Ag/AgCl sponges toward practical desalination of brackish and saline waters.
Published Version
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