Inverted Capacitive Deionization with Highly EnhancedStability Performance Utilizing Ionic Liquid-Functionalized CarbonElectrodes

Capacitive deionization (CDI) has attracted widespread attention as an emerging desalination technology. The co-ion repulsion of the anode has a serious impact on the cycle stability of CDI performance. Here, we proposed a new strategy to prevent co-ion repulsion by developing an inverted capacitive deionization (i-CDI) cell using carbon electrodes with completely different charged functional groups. Commercial activated carbon (AC) was treated by nitric acid (N-AC) to introduce the negatively charged COO- on the N-AC electrode. The positively charged AC (P-AC) was obtained by further modified N-AC with ionic liquid (1-aminopropyl-3-methylimidazolium bromide) (APMIB) to graft positively charged imidazolium groups on the surface of P-AC. Through multiple characterizations, compared with pristine AC electrode, the charged functional group layers were grafted on the modified electrodes surface, which greatly enhanced the wettability and ions transportation performance of the electrodes. An asymmetric i-CDI c...