Capacitive deionization

Engineers at LLNL are developing revolutionary desalination technologies that use electricity to remove salt from water using a process called capacitive deionization (CDI).

Using electricity as an efficient desalination technique

CDI removes salt from water using an applied voltage to reversibly adsorb and desorb ions from the surface of a capacitor. After charging the cell, desalinated water inside the capacitor can be swept out for collection. During discharging, a portion of the capacitive energy can be harvested and used to power further desalination.

CDI is fundamentally more energy efficient for treating low salinity brackish water than traditional desalination technologies because it operates at low pressure and can reuse energy stored during the desalination process.

CDI performs efficiently even at small scale, and is ideally suited to treat water in remote locations.

Pioneering a flow-through electrode design for CDI

Capacitive deionization
An artist’s rendition of LLNL’s fte-CDI device desalinating water with HCAM electrodes.

The CDI devices under development at LLNL are made from carefully engineered hierarchical carbon aerogel monoliths (HCAMs). These materials have good electrical conductivity due to their monolithic nature, ample micrometer-sized macropores for allowing water to flow freely through the electrode itself, and high internal surface area due to numerous sub-nanometer pores created by the activation process. The flow-through electrode (FTE) design pioneered by LLNL has the advantage of maintaining high charge efficiency (ions removed/electrical current) without the use of expensive membranes.

Operating a CDI device to achieve optimal throughput and energy efficiency for a given desired separation is non-trivial. At LLNL, we work extensively on understanding how operation-mode physics impacts device performance and long-term stability. We have recently pioneered concepts ranging from understanding CDI cycling charge efficiency to how to properly define relevant performance metrics.

Selective ion removal

Another major application of CDI is for selective ion removal. We are developing operation modes and engineered carbon materials for the purpose of selectively removing nitrate and hardness (calcium, magnesium). By tuning our material pore structure, we have demonstrated exceptional intrinsic selectivities for nitrate over common interferent ions like chloride and sulfate.

For information about licensing LLNL CDI technology, please contact Annemarie Meike (meike1 [at] (meike1[at]llnl[dot]gov)).




Michael profile picture

Michael Stadermann

PI, technology lead

Patrick profile picture

Patrick Campbell

PI, electrode synthesis and functionalization, device fabrication

Maira profile picture

Maira Ceron Hernandez

Electrode synthesis and functionalization, device fabrication

Steven profile picture

Steven Hawks

Device physics and modeling, systems engineering, desalination operations

Colin profile picture

Colin Loeb

Electrode synthesis and functionalization

No profile picture

Diego Oyarzun

Selectivity, carbon corrosion, systems engineering

Tuan Anh profile picture

Tuan Anh Pham

Atomistic simulations and modeling

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