Ti3C2Tx Intercalated with LaNiO3 Nanocubes as Freestanding Electrodes with Synergistically Enhanced Capacitive Performance for Supercapacitors

The practical application of Ti 3 C 2 T x MXene in supercapacitors is hindered by its tendency to spontaneously restack, which reduces accessible active sites and impedes charge transport kinetics. To address this challenge, a synergistic strategy is proposed: hydrothermally derived LaNiO 3 perovskite nanocubes are integrated into Ti 3 C 2 T x nanosheets via vacuum-assisted filtration, constructing a freestanding Ti 3 C 2 T x /LaNiO 3 composite electrode. The uniformly dispersed LaNiO 3 nanocubes act as interlayer spacers to inhibit MXene restacking and contribute capacitance, meanwhile, the conductive Ti 3 C 2 T x matrix ensures rapid electron transfer. As a result, the optimized composite exhibits a higher specific capacitance (206.8   F   g -1 at 0.5   A   g -1 ) than pristine Ti 3 C 2 T x , and demonstrates ultralong cycling stability (99.8% retention of the initial capacitance after 20,000 cycles at 5   A   g -1 ). Furthermore, a quasi-solid-state asymmetric device (Ti 3 C 2 T x /LaNiO 3 //N-doped graphene) assembled from the composite achieves an energy density of 12.63   Wh   kg -1 at a power density of 450.2   W   kg -1 and maintains 88.6% of its capacitance after 10,000 cycles. Overall, this work provides a promising strategy for designing advanced MXene-based freestanding electrodes by intercalating perovskite nanocubes for next-generation energy storage systems.