In this work, we briefly review the basics of the structure of the electrical double layer (EDL), with emphasis on the amount of neutral salt that can be accumulated in the EDLs of opposite electrodes when a potential difference is applied. Consideration is taken of the realistic solution taking into account that ions have finite volumes and have a limited concentration at any point, as well as to the effect of ion charge. As a result of this accumulation, ionic solutions in contact with the electrodes can be partially deionized, and brine water can eventually transform into potable one. The technology has been denominated CDI or Capacitive DeIonization, as it is based on the high electrical capacitance that can be associated to the EDLs. We give a brief account of how CDI can be implemented and the achievements that can be reached taking into account the EDL structure. Variations such as MCDI (membrane-CDI) or SE-CDI (soft electrodes CDI) are also described. The advantages of capacitive deionization regarding specific ions withdrawal from solutions, as well as the energy requirements for deionization are also discussed.

在这项工作中，我们简要回顾了双电层（EDL）结构的基础知识，重点介绍了在施加电势差时可在相对电极的EDL中累积的中性盐量。考虑到现实的解决方案，要考虑到离子具有有限的体积，并且在任何点上的浓度都有限，以及离子电荷的影响。由于这种积累，与电极接触的离子溶液可能会部分去离子，盐水最终会变成可饮用的溶液。该技术已被称为CDI或电容去离子化，因为它基于可与EDL相关的高电容。我们简要介绍了如何实施CDI，并考虑到EDL结构可以取得的成就。还描述了诸如MCDI（膜CDI）或SE-CDI（软电极CDI）之类的变体。还讨论了电容式去离子在从溶液中抽出特定离子方面的优势，以及去离子所需的能量。