Two-Dimensional Materials for High-Energy Solid-State Asymmetric Pseudocapacitors with High Mass Loadings

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Pseudocapacitors require porous nanostructures and high mass loading for optimal electrochemical performance.
• Current pseudocapacitive materials achieve high capacitances only at low mass loadings (<1 mg cm⁻²), as increased loading hinders ion and electron transport.
• Developing high-mass-loading electrodes with efficient charge transport remains a significant challenge.

Purpose of the Study:

• To engineer high-mass-loading electrodes for pseudocapacitors that maintain efficient ion and electron transport.
• To investigate the electrochemical performance of 2D manganese dioxide (MnO2) and molybdenum disulfide (MoS2) nanosheets supported on carbon fibers (CF) at high mass loadings.
• To construct and evaluate a solid-state asymmetric supercapacitor using these advanced electrodes.

Main Methods:

• Fabrication of 2D MnO2 and MoS2 nanosheets supported on carbon fibers (MnO2@CF, MoS2@CF) with high mass loadings (6.6-7.2 mg cm⁻²).
• Electrochemical characterization of the electrode materials, including areal capacitance and cycling stability measurements.
• Assembly of a pliable, solid-state asymmetric supercapacitor using MnO2@CF and MoS2@CF electrodes (14.2 mg cm⁻² total mass loading).

Main Results:

• MnO2@CF and MoS2@CF electrodes exhibited high areal capacitances (1187 and 495 mF cm⁻², respectively) at high current densities with excellent stability.
• The solid-state asymmetric supercapacitor achieved an energy density of 2.305 mWh cm⁻³ at a power density of 50 mW cm⁻³.
• The device demonstrated remarkable capacitance retention (92.25% over 11,000 cycles) and low diffusion resistance (1.72 Ω s⁻¹/²).

Conclusions:

• The rationally designed nanostructured electrodes with high mass loading overcome limitations in pseudocapacitor performance.
• These materials offer a promising pathway for developing supercapacitor devices with superior energy and power densities.
• The developed solid-state supercapacitor demonstrates potential for practical applications requiring high performance and stability.