Evaluation of Co-Ion Desorption and Faradaic Losses in Capacitive Deionization

The efficiency of Capacitive Deionization (CDI) is largely determined by the charge loss associated with two distinct parasitic processes, namely, co-ion expulsion and faradaic reactions. There is wide agreement that the first factor dominates the inefficiency of CDI; however, the evaluation of the relative incidence of co-ion repulsion on CDI inefficiency remains somewhat elusive. In this work, in the assumption of relatively small ohmic losses, we propose a simple model to quantify charge losses due to either of these processes in CDI cells, disregarding ohmic losses.