Galvanostatic synthesis of MnO2 in carbon cloth: an electrochemical impedance spectroscopy study

Abstract

In the present work, MnO 2 was electrodeposited (galvanostatic mode) on carbon cloth (CC) from manganese nitrate and sulfate precursors. Its electrochemical performance was evaluated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), which were used to study the complex behavior of the material. In CV analysis, higher cathodic and anodic loads were obtained for sulfate-MnO 2 compared with nitrate-MnO 2 , whereas in the Nyquist graphs of the EIS technique, the nitrate-MnO 2 material obtained larger charge transfer resistance (Rtc) than sulfate-MnO 2 . In the Bode analysis, the behavior of sulfate-MnO 2 was better than that of nitrate-MnO 2 . because for this analysis, the phase angle is smaller, which is attributed to better pseudocapacitive behavior of sulfate than nitrate. In capacitance and complex power terms, the relaxation time constant obtained was 2.65 s. The real capacitance in C′(ω) was 107 F g −1 for nitrate-MnO 2 and 197 F g −1 for sulfate-MnO 2 , and the intersection of the complex power curves occurred at 70%. The obtained results suggest that these materials are attractive for application in energy storage devices.

High‐performance symmetric supercapacitor based on molybdenum disulfide/poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate) composite electrodes deposited by spray‐coating

“…Thus, the device turns to behave as a capacitor at higher frequencies. The same phenomenon can be found in a recent work that uses pseudocapacitive materials as electrodes 95 . For the PEDOT, 1:1, and 1:3 devices, the time constant was found to be 90 ms.…”

“…On the contrary, for frequencies lower than f 0 the supercapacitor will behave predominantly like a capacitance. Moreover, the intercept point can also be interpreted as the state where the device releases energy more efficiently 95 …”

“…The same phenomenon can be found in a recent work that uses pseudocapacitive materials as electrodes. 95 For the PEDOT, 1:1, and 1:3 devices, the time constant was found to be 90 ms. This behavior is in accordance with the results shown in the Ragone plot of Figure 6D, since the 1:1, 1:3, and PEDOT supercapacitors presented the higher power densities.…”

“…Moreover, the intercept point can also be interpreted as the state where the device releases energy more efficiently. 95 We calculated the time constants by taking the frequency at the crossing point between jPj/jSj and jQj/jSj curves, as mentioned before. The as-calculated time constant for the MoS 2 device was 4.5 seconds.…”

Synthesis and Environmental Applications of Manganese Oxides

“…The Low-frequency region starts at the beginning of the semicircle (Rs-series resistance) in the high-frequency region corresponds to the resistances of the electrolyte solution was about 5 ohms. The observed Rct value was 16 ohms which considered decent capacitance property for an electrode [246].…”