### 电容去离子除氯电极的构建及其脱盐性能研究进展

1. 1 同济大学长江水环境教育部重点实验室，上海 200092
2 上海海洋大学海洋生态与环境学院，上海 201306
3 上海污染控制与生态安全研究院，上海 200092
• 收稿日期:2020-06-12 录用日期:2020-07-07 发布日期:2020-07-13
• 通讯作者: 马杰 E-mail:jma@tongji.edu.cn
• 作者简介:马杰，教授，博士生导师，2009年博士毕业于上海交通大学，长期从事环境修复材料及电容去离子电极材料的设计和开发，主持国家自然科学基金3项及多项省部级课题的实施
• 基金资助:
国家自然科学基金(21777118)

### Research Progress in Chlorine Ion Removal Electrodes for Desalination by Capacitive Deionization

Yuecheng Xiong1, Fei Yu2, Jie Ma1,3,*()

1. 1 Key Laboratory of Yangtze River Water Environment, Tongji University, Shanghai 200092, China
2 College of Marine Ecology and Environment, Shanghai Ocean University, Shanghai 201306, China
3 Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
• Received:2020-06-12 Accepted:2020-07-07 Published:2020-07-13
• Contact: Jie Ma E-mail:jma@tongji.edu.cn
• About author:Jie Ma, Email: jma@tongji.edu.cn
• Supported by:
the National Natural Science Foundation of China(21777118)

Abstract:

Sustainable freshwater supply is a grave challenge to the society because of the severe water scarcity and global pollution. Seawater is an inexhaustible source of industrial and potable water. The relevant desalination technologies with a high market share include reverse osmosis and thermal distillation, which are energy-intensive. Capacitive deionization (CDI) is a desalination technology that is gaining extensive attention because of its low energy consumption and low chemical intensity. In CDI, charged species are removed from the aqueous environment via applying a voltage onto the anode and cathode. For desalination, Na+ and Cl- ions are removed by the cathode and anode, respectively. With the boom in electrode materials for rechargeable batteries, the Na+ removal electrode (cathode) has evolved from a carbon-based electrode to a faradaic electrode, and the desalination performance of CDI has also been significantly enhanced. A conventional carbon-based electrode captures ions in the electrical double layer (EDL) and suffers from low charge efficiency, thus being unsuitable for use in water with high salinity. On the other hand, a faradaic electrode stores Na+ ions through a reversible redox process or intercalation, leading to high desalination capacity.However, the Cl- removal electrode (anode) has not yet seen notable development. Most research groups employ activated carbon to remove Cl-, and therefore, summarizing Cl- storage electrodes for CDI is necessary to guide the design of electrode systems with better desalination performance. First, this review outlines the evolution of CDI configuration based on the electrode materials, suggesting that the anode and cathode are of equal importance in CDI. Second, a systematic summary of the anode materials used in CDI and a comparison of the characteristics of different electrodes, including those based on Ag/AgCl, Bi/BiOCl, 2-dimensional (2D) materials (layered double hydroxide (LDH) and MXene), redox polymers, and electrolytes, are presented. Then, the underlying mechanism for Cl- storage is refined. Similar to the case of Na+ storage, traditional carbon electrodes store Cl- via electrosorption based on the EDL. Ag/AgCl and Bi/BiOCl remove Cl- through a conversion reaction, i.e., phase transformation during the reaction with Cl-. 2D materials store Cl- in the space between adjacent layers, a process referred as ion intercalation, with layered double hydroxide (LDH) and MXene showing higher Cl- storage potential. Redox polymers and electrolytes allow for Cl- storage via redox reactions. Among all the materials mentioned above, Bi/BiOCl and LDH are the most promising for the construction of CDI anodes because of their high capacity and low cost. Finally, to spur the development of novel anodes for CDI, the electrodes applied in a chlorine ion battery are introduced. This is the first paper to comb through reports on the development of anode materials for CDI, thus laying the theoretical foundation for future materials design.

MSC2000:

• O646