Untapped Potential of Polymorph MoS₂: Tuned Cationic Intercalation for High-Performance Symmetric Supercapacitors

Abstract

Supercapacitors have been the key target as energy storage devices for modern technology that need fast charging. Although supercapacitors have large power density, modifications should be done to manufacture electrodes with high energy density, longer stability, and simple device structure. The polymorph MoS2 has been one of the targeted materials for supercapacitor electrodes. However, it was hard to tune its phase and stability to achieve the maximum possible efficiency. Herein, we demonstrate the effect of the three main phases of MoS2 (the stable semiconductor 2H, the metastable semiconductor 3R, and the metastable metallic 1T) on the capacitance performance. The effect of the cation intercalation on the capacitance performance was also studied in Li2SO4, Na2SO4, and K2SO4 electrolytes. The performance of the electrode containing the metallic 1T outperforms those of the 2H and 3R phases in all electrolytes, with the order 1T > 3R > 2H. The 1T/2H phase showed a maximum performance in the K2SO4 electrolyte with a specific capacitance of 590 F g–1 at a scan rate of 5 mV s–1. MoS2 showed a good performance in both positive and negative potential windows allowing the fabrication of symmetric supercapacitor devices. The 1T MoS2 symmetric device showed a power density of 225 W/kg with an energy density of 4.19 Wh/kg. The capacitance retention was 82% after 1000 cycles, which is an outstanding performance for the metastable 1T-containing electrode.

Fullerene C76: An Unexplored Superior Electrode Material with Wide Operating Potential Window for High‐Performance Supercapacitors

“…To measure the difference in resistance between the active materials, the electrochemical impedance spectroscopy (EIS) measurements were performed in the frequency range of 100 kHz to 100 mHz. The specific capacitance of the active materials was calculated using the data obtained from the CV and GCD experiments using reported equations . The charge storage mechanism can be generally illustrated using the cyclic voltammogram .…”

“…However, currently developed supercapacitors lack the energy density needed to achieve such a challenging goal . Therefore, researchers are targeting the development of supercapacitor electrode materials with high power and energy densities . A typical supercapacitor device mainly depends on the adsorption/desorption of ions on its surface, namely the electrical double layer (EDL).…”

Revealing the role of the 1T phase on the adsorption of organic dyes on MoS2 nanosheets

“…Two-dimensional (2D) layered materials have attracted attention for a wide range of applications including hydrogen evolution, 1 adsorption, 2,3 photocatalysis, 4,5 lithium ion batteries, 6 and supercapacitors. [7][8][9] Among the different types of 2D materials, molybdenum disulde (MoS 2 ) has been one of the most studied materials over the last few years. 10,11 MoS 2 can exist in three phases; two are semiconducting and stable (hexagonal, 2H, and rhombohedral, 3R) and the third (1T) is metallic with a trigonal structure.…”

“…[1][2][3][4]6,7,12,20 However, several contradicting reports on this topic can be found due to the very delicate nature of the material. [1][2][3][4][6][7][8][9] The electronic structure of the material and its activity are quite sensitive to several parameters including the molybdenum local coordination, surface defects, crystal phase, degree of exfoliation, and the size and morphology of the nanosheets. For instance, several reports claimed fast and efficient adsorption of different organic dyes using MoS 2 composites.…”

Recycling of Li−Ni−Mn−Co Hydroxide from Spent Batteries to Produce High‐Performance Supercapacitors with Exceptional Stability

“…[31] Figure 3c depicts the CCCD graphs at different current densities (1-4 A g À 1 ), showing nonlinear curves of potential versus time, which confirm the battery-like behavior of the recycled material. [32,33] The specific capacitance of the recycled material was calculated from the CCCD graphs using Eq. 1:…”