Direct prediction of the desalination performance of porous carbon electrodes for capacitive deionization

作者：S. Porada, Lars Borchardt, Martin Oschatz, Marek Bryjak, Jennifer S. Atchison, Karel J. Keesman, Stefan Kaskel, P. Maarten Biesheuvel, Volker Presser · 发表于：Energy & Environmental Science · 年份：2013 · DOI：10.1039/c3ee42209g · 被引用次数：571 · 研究领域：Membrane-based Ion Separation Techniques、Membrane Separation Technologies、Supercapacitor Materials and Fabrication

Desalination by capacitive deionization (CDI) is an emerging technology for the energy- and cost-efficient removal of ions from water by electrosorption in charged porous carbon electrodes. A variety of carbon materials, including activated carbons, templated carbons, carbon aerogels, and carbon nanotubes, have been studied as electrode materials for CDI. Using carbide-derived carbons (CDCs) with precisely tailored pore size distributions (PSD) of micro- and mesopores, we studied experimentally and theoretically the effect of pore architecture on salt electrosorption capacity and salt removal rate. Of the reported CDC-materials, ordered mesoporous silicon carbide-derived carbon (OM SiC-CDC), with a bimodal distribution of pore sizes at 1 and 4 nm, shows the highest salt electrosorption capacity per unit mass, namely 15.0 mg of NaCl per 1 g of porous carbon in both electrodes at a cell voltage of 1.2 V (12.8 mg per 1 g of total electrode mass). We present a method to quantify the influence of each pore size increment on desalination performance in CDI by correlating the PSD with desalination performance. We obtain a high correlation when assuming the ion adsorption capacity to increase sharply for pore sizes below one nanometer, in line with previous observations for CDI and for electrical double layer capacitors, but in contrast to the commonly held view about CDI that mesopores are required to avoid electrical double layer overlap. To quantify the dynamics of CDI, we develop...