Two-dimensional Co-BTB/MX composite nanosheets for high-performance supercapacitor electrodes

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In this study, a series of novel two-dimensional (2D) Co-BTB/MX composite nanosheets were successfully synthesized through strong electrostatic interactions between metal-organic framework (MOF) nanosheet Co-BTB and MXene. X-Ray diffraction (XRD) analysis reveals that the composite of Co-BTB and MXene expands the interlayer spacing of MXene, and effectively prevents the stacking of MXene nanosheets, which allows them to serve as a structural buffer that accommodates the volume expansion of Co-BTB during cycling, thereby enhancing the conductivity and stability of the composite nanosheets. The Co-BTB/MX-2 electrode exhibits exceptional electrochemical performance, delivering a high specific capacitance of 2954.0 F·g⁻¹ at 1 A·g⁻¹, marking a 115.3% increase compared to the pure Co-BTB electrode (1372.0 F·g⁻¹), while demonstrating superior cycling stability with a 108.9% capacitance retention after 1000 cycles at 10 A·g⁻¹. Furthermore, the Co-BTB/MX-2 //AC based device was fabricated, which achieved a maximum energy density of 121.36 Wh·kg⁻¹ at a power density of 1700.0 W·kg⁻¹, along with an outstanding long-term cycling stability, retaining 94.5% of its initial capacitance after 9000 charge-discharge cycles, which substantially surpasses that of the Co-BTB //AC based device. This study provides a promising strategy for the design and synthesis of novel composite materials derived from a diverse class of 2D materials, paving the way for advanced energy storage applications.