Self-Assembly of Ba2+ Pillared Ti3C2 with Enlarged Interlayer Spacing Towards Improved Supercapacitive Performance

MXenes have excellent electrochemical performance due to their remarkable electrical conductivity and abundant surface functional groups. However, the smaller interlayer spacing and self-stacking limit their practical applications. Herein, the Ba[Formula: see text] ions pillared Ti3C2 MXene (Ba[Formula: see text]–Ti3C[Formula: see text] with enlarged interlayer spacing has been successfully fabricated by electrostatic self-assembly. The pillared Ba[Formula: see text] ions between Ti3C2 layers can enlarge interlayer spacing, increase specific surface area, expose more active sites and provide open ions transfer channels due to its pillaring effects on the layered structure of Ti3C2. The Ba[Formula: see text]–Ti3C2 exhibits a higher specific capacitance (168[Formula: see text]F[Formula: see text] at 0.2[Formula: see text]A[Formula: see text] than pure Ti3C2 (123 F[Formula: see text] at 0.2[Formula: see text]A[Formula: see text]g[Formula: see text] and outstanding cycle performance, which remains at 164 F[Formula: see text] after 1100 cycles at 1[Formula: see text]A[Formula: see text]. The Ba[Formula: see text]–Ti3C2//AC asymmetric supercapacitor achieved a high power density of 1140[Formula: see text]W[Formula: see text]Kg[Formula: see text] as well as long cycle stability with capacitance retention of 86.35% at a current density of 1[Formula: see text]A[Formula: see text]g[Formula: see text] after 4000 cycles. The results demonstrate that expeading interlayer spacing can obviously enhance and optimize the supercapactive performance of MXenes, providing an idea to design the 2D energy storage materials with large interlayer spacing and high rate capability.