Silicon intercalation on MXene nanosheets towards new insights into a superior electrode material for high-performance Zn-ion supercapacitor

MXenes seem promising as a new two-dimensional (2D) material for energy storage and conversion applications due to their excellent conductivity, efficient accordion-like layered structure, surface chemistry, and many organized nanochannels. Nevertheless, the demonstration of MXenes' superiority is impeded by an accumulation of interlayers and the chemical sluggishness of structural components. With silicon (Si) pre intercalation techniques on V2CTx, MXene is able to increase its interlayer spacing and excite the outermost vanadium atoms, resulting in a frequent transfer and high storage capability of Zn-ions in supercapacitors (SCs). Motivated by the distinctive properties of Si and MXene, we have reported the V2CTx@Si nanocomposite electrode material for SC in this work. Si nanospheres act as spacers to intercalate into the MXene interlayers, increasing the ion transport channels while simultaneously lowering the ion transport resistance. The V2CTx@Si nanocomposite electrode delivers a maximum specific capacitance of 557.7 F/g at 1 A/g. The outstanding performance of the V2CTx@Si electrode material is demonstrated by DFT simulations, thanks to its electronic characteristics. These findings indicate that the V2CTx@Si possesses enhanced conductivities than the pristine MXene, which is beneficial for the rate performance of V2CTx@Si. The obtained Eads value of the V2CTx@Si is −0.845 eV, higher than the pristine material (−0.652 eV), indicating energetically favorable. A zinc–ion supercapacitor (ZISC) is constructed via coupling V2CTx@Si as a cathode and Zn foil as an anode (denoted as V2CTx@Si//Zn). The V2CTx@Si//Zn can function at a wide potential range of 1.8 V and provide a high capacitance of 318.25 F/g at 1 A/g with a consistent cyclic life (96.4 %) up to 10,000 cycles. Furthermore, the V2CTx@Si//Zn possessed a maximum energy density of 143.33 Wh/kg at a power density of 900.72 W/kg, outperforming previously reported similar work.