Interlayer engineered MoB MBene/CNTs microelectrodes for high-performance flexible microsupercapacitors

Two-dimensional transition-metal borides, known as MBenes, are promising electrode materials for microsupercapacitors (MSCs) because of their excellent mechanical properties, hydrophilic surfaces, metallic conductivity, and rich surface chemistry. However, strong van der Waals interactions cause MBene nanosheets to restack, which reduces electrochemically active sites and limits ion transport. In this work, carbon nanotubes (CNTs) were incorporated into the layered MBene framework, where they are distributed through accessible inter-sheet regions and form an interconnected conductive network that mitigates severe restacking. This structure improves the connection between adjacent MBene sheets, promotes charge transfer, and provides more accessible pathways for electrolyte ions. The MBene/CNTs composite delivered a high areal capacitance of 196 mF cm⁻ 2 at 2 mV s⁻ 1 . The assembled flexible MBene/CNTs MSC achieved an areal capacitance of 94.5 mF cm⁻ 2 and an areal energy density of 5.43 μWh cm⁻ 2 at an areal power density of 1 mW cm⁻ 2 . The device also retained 94.4% of its initial capacitance after 1600 cycles and maintained more than 95% capacitance retention when bent from 0° to 120°. Density functional theory (DFT) calculations reveal interfacial charge redistribution between MBene and CNTs together with regulated K adsorption behavior at the composite interface. These results show that the interlayer engineered MBene/CNTs structure is an effective design for flexible microscale energy-storage devices with high capacitance, good stability, and mechanical flexibility.