n the materials side, new materials and design strategies for novel and improved electrodes continue to emerge. Fundamentally, even the very basic question of the “best” material remains unanswered. Naturally, the choice of electrode material largely depends on required performance (desalting capacity, final salt concentration), system requirements (flow rate, stack configuration), and cost considerations (efficiency, material cost, lifetime). However, we are currently only starting to understand CDI operation on a quantitative and kinetic basis. Ongoing research is not only dedicated to further optimizing the pore size distribution and chemical composition of already known carbons, but also expands to novel materials and complex pore and electrode architectures