Bimetallic (Co/Ni, Ce) MOF decorated V2CTx MXene/CNT for high energy flexible zinc-ion capacitor

Abstract

This study reports the design and fabrication of a high-performance flexible all-solid-state zinc-ion capacitor based on a novel ternary composite, comprising V₂CT_x MXene (T_x = F, O, Cl, and OH), functionalized carbon nanotubes, and cobalt/nickel–cerium bimetallic metal–organic frameworks. The optimal binary composite ratio was determined through structural, morphological, and electrochemical analyses. Integration with bimetallic (Co and Ce or Ni and Ce) metal–organic framework yielded a ternary composite, which exhibited outstanding electrochemical performance in ZnSO₄/KCl electrolyte, achieving a specific capacitance of 1163.2 F g⁻¹ at 2 A g⁻¹. The synergistic combination of high electrical conductivity from functionalized carbon nanotubes, multiple redox-active centers from Co/Ni, Ce, and V species, and the ion intercalation capability of MXene contributed to superior energy storage performance. The assembled flexible all-solid-state zinc-ion capacitor device delivered a remarkable specific capacitance of 667.7 F g⁻¹, an energy density of 133.5 Wh kg⁻¹, and a power density of 1799.5 W kg⁻¹, with 92% capacitance retention over 10 000 cycles and excellent mechanical stability under repeated bending. It establishes the development of promising electrode materials for next-generation flexible and wearable energy storage devices. This study first investigates such a unique combination of V₂CT_x/functionalized carbon nanotube supported bimetallic metal organic framework for a flexible zinc-ion capacitor.