A redox-flow battery (RFB) has been established for continuous ion separation based on reversible redox reactions of the Fe(CN)63−/4− electrolyte. Herein, electrospun carbon fibers (CFs) with tailor-made properties were developed at different carbonization temperatures. With a carbonization temperature of 900°C, the CF (CF-900) showed a high degree of graphitization (Id/Ig = 0.92) and low electrode resistance. The cyclic voltammetry curve of CF-900 was composed of evident redox peaks with a high current level, revealing good electrochemical reversibility and high electrochemical activity of the redox reactions. With the CF-900 electrode, a high average salt removal rate (ASRR) of 97.5 μg/min/cm2 was achieved at 0.4 V while desalinating 10 mM NaCl, which was 1.4-fold higher than in the absence of the CF electrode. Moreover, the addition of the CF-900 electrode greatly improved the charge efficiency (96 …