Nanosized V2CTx with Boosting Super Capacitance via Engineering Alkalization Assisted K+ Interlayer Coordination

Abstract

Although V2CTx MXenes is extremely attractive as electrodes for supercapacitors, a bottleneck that restricted its application was set due to the lengthened ion pathway and the resulting F-based surface terminations, which creates a barrier for the V2CTx to achieve increased capacity. In this work, the nano-sized V2CTx with enlarged interlayer space and decreased F-based surface terminations was synthesized by alkalization assisted K+ interlayer coordination, exhibiting an ultra-high capacitance of 665 F g−1 at 2 mV s−1 in 1 M H2SO4 with capacitance retention rates of 81.9% after 10000 charge/discharge cycles. Moreover, it also produces a good specific capacitance in Li2SO4 and KOH with excellent stability. This excellent performance can be attributed to the porous structure with atomic increase of interlayer spacing (0.969 nm), reduced flake size, as well as small holes generated, which will greatly shorten ion transport and provide an ion “highway.”