Enhanced supercapacitive performance of Mo1.33C MXene based asymmetric supercapacitors in lithium chloride electrolyte
Ahmed El Ghazaly, Weitao Zheng, Joseph Halim, Eric Néstor Tseng, Per O. Å. Persson, Bilal Ahmed, Johanna Rosén
Abstract
Two-dimensional (2D) Mo1.33C MXene renders great potential for energy storage applications and is mainly studied in the sulfuric acid (H2SO4) electrolyte. However, H2SO4 limits the electrode potential to 0.9 V for symmetric devices and 1.3 V for asymmetric devices. Herein, we explore the electrochemical behavior of Mo1.33C MXene in LiCl electrolyte. In comparison to H2SO4, LiCl electrolyte is a neutral salt with high solubility at room temperature and low hazardousness. The analysis shows a volumetric capacitance of 815 Fcm−3 at a scan rate of 2 mVs−1 with a large operating potential window of -1.2 to +0.3V (vs. Ag/AgCl). This is further exploited to construct MXene-based asymmetric supercapacitors Mo1.33C//MnxOn, and the electrochemical performance is evaluated in 5M LiCl electrolyte. Owing to the wide voltage widow of the Mo1.33C//MnxOn devices (2V) and high packing density of the electrodes, we have achieved a volumetric energy density of 58 mWh/cm3, a maximum power density of 31 Wcm−3 and retained 92% of the initial capacitance after 10,000 charge/discharge cycles at 10 A g−1. One of the main value propositions of this work, aside from the high energy density, is the outstanding columbic efficiency (100%), which ensures excellent cyclic stability and is highly desirable for practical applications.