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Capacitive deionization (CDI) is a highly energy-efficient and environment-friendly alternative for desalination. Activated carbon (AC) is the most frequently used electrode material for desalination due to their unique porous structure and high specific surface area. In general, the desalination performance of CDI systems deteriorates considerably after long-term operation, limiting their practical applications. This deterioration can be various for different AC electrodes. This study aimed to investigate the long-term stability and desalination performance of CDI systems in tap water by using titanium- and graphite-based electrodes. The nanostructured TiO2/AC composite slurry was prepared and cast onto titanium foil or graphite paper as current collectors. Results showed that the adhesion strength of carbon material to titanium foil reduced significantly (~ 50％) after immersion of the electrode samples in tap water for 7 days. In contrast, graphite-based electrides presented high stability (＜ 1％), owing to strong adhesion strength of carbon material to graphite current collectors. In addition, the graphite-based electrode exhibited lower impedance (＜ 1 ohm) and higher specific capacitance (＞ 50 F/g) compared to titanium-based electrode after being immersed in tap water for 6 months. The desalination rate reached 84.3％ when using 23 pairs of titanium-based electrodes in a CDI system. However, the desalination efficiency declined considerably by over 20％ in the 60-day desalination test. On the contrary, 15 pairs of graphite-based electrodes was capable of achieving the same desalination performance compared to titanium-based electrodes. Besides, the desalination efficiency of graphite-based electrodes was reduced by only 4.9％. These results demonstrate that the application of highly durable graphite-based electrodes can improve the long-term desalination performance of CDI system.

Author：趙淑如,王鈞逸,劉柏逸,鐘琍菁,邵信,張敏超,洪仁陽,梁德明,
★Article source：6th International Conference on Battery Deionization ＆ Electrochemical Separation