Timeline on the application of intercalation materials in Capacitive Deionization

The relative insignificance of advanced materials in enhancing the energy efficiency of desalination technologies

“…In the case of carbon electrodes, ions are immobilized in the electrical double layers (EDLs) of the electrode micropores, whereas with battery electrodes, ions intercalate into the lattice structure. [84][85][86] Upon short circuiting or reversing the polarity of the electrodes, the ions are released back into solution, creating a brine stream.…”

“…10,82,87 Though some research has been directed towards operation modes, cell architectures, and energy recovery, the overwhelming majority of efforts have focused on the development of novel electrode materials. 84,86,87 With the electrodes being the key component of the CDI technology, material properties of electrodes are expected to largely influence the overall performance.…”

“…[92][93][94] Pseudocapacitive electrode materials are defined by their use of ion intercalation as a method for ion removal-either as the sole mechanism or in conjunction with EDL-based ion capture. 86,[95][96][97][98][99] The CDI field has commonly used charge efficiency (moles of salt removed per moles of electrical charge supplied), salt adsorption capacity, and average salt adsorption rate (ASAR) as the primary metrics for assessing the performance of electrode materials. 10 However, these parameters are limited to the evaluation of CDI, and therefore are unsuitable for comparison with other technologies.…”

“…However, it is important to note that although pseudocapacitive materials allow operation at lower potentials and possess exceptional salt adsorption capacities in comparison to activated carbon, they typically suffer from very low electrical conductivity. 105,106 The high electrical resistances of pseudocapacitive materials would require operation at low current densities to avoid significant irreversible losses, resulting in stunted rates of water production. Hence, regardless of the large salt adsorption capacities of pseudocapacitive materials, mass transfer limitations of ion intercalation and large electronic resistances are likely to limit their practically achievable energy efficiency in a similar manner to EDL-based materials (Fig.…”

Dual‐Zinc Electrode Electrochemical Desalination

“…These desalination devices operate by the use of individual capture/release of ions by two separate electrode materials. The removal capacity is limited by the intrinsic specific capacity of the electrode materials, and cell operation still alternates between half‐cycles of desalination (charging) and regeneration (discharging), which makes continuous operation impossible . Semicontinuous operation could be enabled by alternating the two channels in a manner synchronized with the direction of the applied current.…”