3D Capacitive Deionization Electrode Supported By Carbon Fiber/Felt Framework with Ordered Macropores for Brackish Water Desalination

Capacitive Deionization (CDI) is an emerging technology for brackish water desalination. To achieve scaling electrodes with a commercial mass loading, carbon fiber/felt was employed as framework to build 3D composite electrode. The highly conductive carbon fiber/felt can serve as electron transfer channel and also provide macrostructure while activated carbon (AC) with microstructure was loaded to furnish ionic adsorption sites. The electrochemical characterization of 3D composite with carbon felt (1 cm2) showed a larger total ion storage capacity (25 F g−1, 40 mg cm−2, 0.79 F) as compared to an AC film electrode (93 F g−1, 1.5 mg cm−2, 0.11 F). It was then tested in a 10 cm2 CDI cell reaching salt adsorption capacity (SAC) values of 5.2–8.7 mg g−1 and 57–67% in charge efficiency. In addition, the 3D composite was scaled to a 300 cm2 stack demonstrating excellent performance (8.7 mg g−1SAC, 2.6gSALT m−2 h−1 and 63% charge efficiency). Similarly, the 3D composite with carbon fiber as the framework and ordered macropores by the introduction and removal of a second fiber showed lower ohmic drop and higher deionization performance than the AC film electrode and also the ones with only carbon fiber. Therefore, these 3D composite electrode supported by carbon fiber/felt framework can be a great promise for large-scale CDI practical applications.