Reversible electrochemical processes are a promising technology for energy-efficient water treatment. Electrochemical desalination is based on the compensation of electric charge by ionic species, through which the ions are immobilized and, thereby, removed from a feed-water stream flowing through a desalination cell. For decades, electrochemical desalination has focused on the use of carbon electrodes, but their salt-removal ability is limited by the mechanism of ion electrosorption at low molar concentrations and low charge-storage capacity. Recently, charge-transfer materials, often found in batteries, have demonstrated much larger charge-storage capacities and energy-efficient desalination at both low and high molar strengths. In this Review, we assess electrochemical-desalination mechanisms and materials, including ion electrosorption and charge-transfer processes, namely, ion binding with redox-active polymers, ion insertion, conversion reactions and redox-active electrolytes. Furthermore, we discuss performance metrics and cell architectures, which we decouple from the nature of the electrode material and the underlying mechanism to show the versatility of cell-design concepts. These charge-transfer processes enable a wealth of environmental applications, ranging from potable-water generation and industrial-water remediation to lithium recovery and heavy-metal-ion removal.

可逆电化学过程是用于节能水处理的有前途的技术。电化学脱盐基于离子种类对电荷的补偿，离子通过离子种类的固定化，从而从流过脱盐池的给水流中去除。几十年来，电化学脱盐一直集中在碳电极的使用上，但是其脱盐能力受到低摩尔浓度和低电荷存储能力下离子电吸附机理的限制。近来，通常在电池中发现的电荷转移材料在低摩尔强度和高摩尔强度下均显示出更大的电荷存储能力和高能效的脱盐能力。在这篇评论中，我们评估了电化学脱盐的机理和材料，包括离子电吸附和电荷转移过程，即与氧化还原活性聚合物的离子结合，离子插入，转化反应和氧化还原活性电解质。此外，我们讨论了性能指标和电池体系结构，我们将它们与电极材料的性质和基本机制分离开来，以显示电池设计概念的多功能性。这些电荷转移过程可实现大量的环境应用，从饮用水生产和工业用水修复到锂回收和重金属离子去除。我们将它们与电极材料的性质以及潜在的机理分离开来，以展示电池设计概念的多功能性。这些电荷转移过程可实现大量的环境应用，从饮用水生产和工业用水修复到锂回收和重金属离子去除。我们将它们与电极材料的性质以及潜在的机理分离开来，以展示电池设计概念的多功能性。这些电荷转移过程可实现大量的环境应用，从饮用水生产和工业用水修复到锂回收和重金属离子去除。