Capacitive Deionization Performance of Thermally Surface Modified Activated Carbon Cloth Electrodes

Capacitive deionization (CDI) is a low energy desalination technology with long-cycle life, which utilizes high-porosity capacitive electrodes for capturing ions from flowing saline water [1, 2]. Though still suffering from relatively low desalination capacity, one major advantage of CDI technology is its low energy requirement and high rate operation for desalination. In recent years, much effort has been put on improving electrode materials for CDI applications. These studies have mostly focused either on the use of novel electrode materials or on surface modifications (e.g. metal oxide growth, chemical treatment, and thermal treatment) of the existing CDI electrode materials [1, 3, 4]. Although thermal treatment of carbon electrodes for improved charge storage is a well-established approach, the effects of various thermal treatment procedures on the performance of CDI electrodes still remain unexplored. Inherent similarities between the operating principles of supercapacitors and CDI technology might make one to think a similar correlation could be established between thermal treatment and the CDI performance. However, due to major differences in required charge storage mechanisms, a detailed study on various treatment conditions should be conducted to understand which conditions specifically promote better ion adsorption in CDI electrodes. Motivated by this, the effects of different thermal treatment conditions (i.e., temperature and gases) on salt adsorption performances of the activated carbon cloth (ACC) electrodes were investigated. Major discrepancy between stored charge versus salt adsorption capacity (SAC) was observed for different treatment conditions. To better assess these effects, additional BET and Raman tests on the ACC electrodes were also conducted. Results indicated interesting observations regarding charge storage capacity and SAC for different treatment conditions, which highlights the importance of selecting a suitable thermal treatment condition for enhancing the CDI performance of ACC electrodes. References [1] S. Porada, R. Zhao, A. van der Wal, V. Presser and P.M. Biesheuvel, Progress in Materials Science , 2013, 58(8), 1388-1442. [2] T. J. Welgemoed and C.F. Schutte, Desalination , 2005, 183(1-3), 327-340. [3] L. G. Zou, G. Morris and D. Qi, Desalination , 2008, 225(1-3), 329-340. [4] M. E. Suss, S. Porada, X. Sun, P. M. Biesheuvel, J. Yoon and V. Presser, Energy and Environmental Science , 2015, 8(8), 2296-2319.