Highly stable MXene/g-PPy@sulfonated cellulose composite electrodes for flexible supercapacitors

Traditional two-dimensional transition metal carbides/nitrides (MXene) have gained much academic concern due to their excellent physicochemical properties, but their susceptibility to self-stacking leads to poor cyclic stability. In this paper, an MXene-based electrode active material was successfully prepared. The generated modified PPy (g-PPy) increases the active site, increases the accessibility of ions, and can give full play to the pseudocapacitance. By the combination of modified PPy (g-PPy) nanoparticles with pseudocapacitive behavior polymerized in situ on sulfonated cellulose (SC) and MXene, not only the electrochemical performance was improved by exploiting the synergy between different electrode materials and different energy storage mechanisms, but also the MXene as a skeleton limited the volume expansion and contraction of PPy during charge/discharge cycles and the g-PPy and SC composites (g-PPy@SC) as a spacer supported the MXene layer, resulting in much higher cycle stability. Cycle stability of 98.4 % even after 10,000 cycle tests. In addition, a symmetric supercapacitor assembled from this electrode material maintains a stability of 84.4 % under 10,000 cycles at a low temperature of −40 °C. Therefore, this study provides a feasible method for the preparation of MXene-based electrodes with high cycling stability.