Sonication-induced microstructural modification of MXene for enhanced supercapacitor performance: Electrochemical characterization and mechanistic insights

MXene is a promising electrode material for micro-supercapacitors (MSCs), but its tendency to stack layers hinders electrolyte ion accessibility and impairs charge storage performance‌. We address this through ice-bath sonication of Ti 3 C 2 T x MXene dispersion, creating a microstructure with expanded interlayer spacing, increased porosity, reduced dimensions with enhanced interface density and active areas, while preserving high electrical conductivity. The resulting MXene-MSC demonstrates superior charge storage performance over its pristine counterpart: 61.3 % higher capacitance (91.8 mF/cm 2 at 5 mV/s), 1.5 times improved rate performance, and 4.2-fold higher energy density, without sacrificing long-term cycling stability. The mechanistic origin of the performance improvement was revealed via electrochemical impedance spectroscopy (EIS) analysis, which demonstrated significantly enhanced ionic diffusion kinetics and faster frequency response. These enhancements are directly ascribed to sonication-induced favorable microstructural features in MXene electrodes, which improve electrolyte accessibility and create optimized ion transport pathways with reduced length and increased efficiency. This work offers new insights into balancing electrical conductivity and ion transportation for high-performance supercapacitors. • The sonicated-MXene MSC exhibited superior charge storage performance. • Sonication of MXene enhanced electrolyte accessibility and ionic diffusion kinetics while caused minimal change in ohmic resistance. • Device performance improvement is attributed to sonication-induced microstructural optimization of MXene electrodes.