Engineering the electrochemical performance of CoWO₄ composites of MXene by transitional metal ion doping for high energy density supercapacitors

This investigation presents a straightforward synthesis method for a CoWO₄@Ti₃C₂T_x composite doped with transitional metals, serving as innovative cathode materials for supercapacitors. The study delves into the structural, morphological, and electrochemical attributes of these composites, revealing that the Ni-doped variant outperforms its Zn/Cu-doped counterparts in capacitive capabilities. Specifically, the Ni-doped MXene composite within the CoWO₄ electrode exhibits a remarkable specific capacitance of 630 F g⁻¹ at a current density of 1 A g⁻¹, showcasing superior performance. Moreover, this composite demonstrates notable cycling stability, retaining 92% of its initial capacitance over 10000 cycles. To further explore practical applications, an asymmetric supercapacitor coin cell (CR2032) was assembled, when displays a high voltage window of 1.6 V in a 1 M H₂SO₄ electrolyte, yielding a specific capacitance of 248 F g⁻¹ at 1 A g⁻¹. Notably, the device achieves an energy density of 63.8 Wh kg⁻¹ at a power density of 422 W kg⁻¹, accompanied by an impressive 95.6% coulombic efficiency. The practical viability of the fabricated supercapacitor prototype is underscored by its ability to power a green light-emitting diode within 10 min of a 10-s charge. This highlights the potential of the composite electrode material for constructing high-performance supercapacitors, assessed morphologically and benchmarked against other metal-doped samples.