Design and plasma-assisted in situ construction of layered MXene/CNTs/NiCo-LDH heterostructures for enhanced electrochemical performance

MXene is a promising electrode material for supercapacitors due to its excellent conductivity, but its self-stacking impedes ion and electron transport. To address this issue, carbon nanotubes (CNTs) were introduced as conductive spacers, and NiCo-layered double hydroxides (LDH) was rapidly deposited via an assisted liquid-phase plasma electrolysis method to construct a stable heterostructure. This design effectively alleviates ion/electron transport resistance, improves charge transfer efficiency, and mitigates the volume expansion of NiCo-LDH during cycling. Density functional theory analysis reveals enhanced electronic conductivity and ion migration at the MXene/CNT/NiCo-LDH heterointerface. Benefiting from the synergistic structure, the electrode achieves a high specific capacitance of 2145 F·g⁻¹ and maintains 95.2% of its initial capacitance after 5000 cycles. The assembled asymmetric supercapacitor delivers an energy density of 41.9 Wh·kg⁻¹ at 425.1 W·kg⁻¹ and retains 91% of capacitance after 5000 cycles. Moreover, the flexible device exhibits remarkable stability under multiple bending angles without distortion of cyclic voltammetry (CV) curves.