Membrane assisted capacitive deionization with binder-free carbon xerogel electrodes

Performance results from the extended operation of CDI and MCDI single cells configured with binder-free mesoporous CX electrodes are presented. A Randle's equivalent circuit consisting of capacitive and resistive impedances was used to simulate the current response of the CDI and MCDI cells. The CDI cell had a lower initial resistance (R_S) but also a lower resistance to current leakage (R_L), and a lower effective capacitance (C_DL) in comparison to the MCDI cell. The simulation model showed good agreement with experimental data, but overestimated the prediction of R_S values. Performance data from conductivity profiles showed improved performance for the MCDI cell, but also inversion spiking for the CDI cell after extended operation. The results suggest that the lower R_L, led to faster oxidation of the electrodes and a degraded CDI performance. In contrast, the MCDI cell showed preserved behavior with extended operation.