Capacitive deionization (CDI) has attracted much attention as a novel desalination technology. However, the oxidation of carbon anode and co-ion repulsion during charging are key issues which limit the CDI development. Inverted capacitive deionization (i-CDI) can attenuate these effects. Here, a simple method was presented to get the self-supporting carbon nanofibers electrodes with opposite surface charges to improve the deionization performance of i-CDI device. The electrospun polyacrylonitrile/polymethyl methacrylate (PAN/PMMA)-derived flexible carbon nanofiber was found to be negatively charged (N-CNF). The positively charged porous carbon nanofiber (P-CNF) was obtained by further heat treatment of N-CNF in the presence of ZnCl₂. The P-CNF possesses much low negative potential of zero charge (PZC = −0.68 V), opposite to N-CNF (+0.32 V), measured by differential capacitance tests. With P-CNF as cathode and N-CNF as anode, the asymmetric capacitor device realized high performance i-CDI, and delivered a super high deionization capacity of 30.4 mg/g and very fast deionization rate (1.0 mg/g/min) with low specific energy consumption. The adsorption-desorption process in i-CDI was analyzed. The device exhibits superior cycling stability and regenerability over 70 cycles. These flexible carbon nanofibers with substantial surface charge difference render it favorable for i-CDI application.

电容去离子（CDI）作为一种新型的海水淡化技术备受关注。然而，充电过程中碳阳极的氧化和共离子排斥是限制 CDI 发展的关键问题。反向电容去离子 (i-CDI) 可以减弱这些影响。在这里，提出了一种简单的方法来获得具有相反表面电荷的自支撑碳纳米纤维电极，以提高 i-CDI 装置的去离子性能。电纺聚丙烯腈/聚甲基丙烯酸甲酯（PAN/PMMA）衍生的柔性碳纳米纤维被发现带负电荷（N-CNF）。在ZnCl ₂存在下进一步热处理N-CNF，得到带正电荷的多孔碳纳米纤维（P-CNF）. P-CNF 具有非常低的零电荷负电位 (PZC = -0.68 V)，与 N-CNF (+0.32 V) 相反，通过差分电容测试测量。以 P-CNF 为阴极，N-CNF 为阳极，该非对称电容器装置实现了高性能 i-CDI，并提供了 30.4 mg/g 的超高去离子容量和非常快的去离子速率（1.0 mg/g/min）和比能耗低。分析了i-CDI中的吸附-解吸过程。该器件在超过 70 次循环后表现出优异的循环稳定性和可再生性。这些具有显着表面电荷差异的柔性碳纳米纤维使其有利于 i-CDI 应用。