K⁺-Pre-Intercalated α-K_0.2MnTi_0.07O_0.8 Hollow Nanotubes for High-Performance Na⁺ Supercapacitors

Transition metal oxides have attracted extensive research interest for supercapacitors due to efficient ion accessibility of nanostructures. Here, hierarchically hollow α-K 0.2 MnTi 0.07 O 0.8 nanotubes with high K content are prepared via a self-sacrificial template method. The electrochemical performance of α-K 0.2 MnTi 0.07 O 0.8 nanotubes is significantly improved when beneficial K + is intercalated into a considerably ordered α-MnO 2 phase with exchangeable Mn–K slabs by a K-pre-reserved reaction. Significantly, the α-K 0.2 MnTi 0.07 O 0.8 nanotubes activated in a K 2 SO 4 electrolyte exhibit highly capable capacitance behavior with high specific capacitance (334.5 F g –1 at 1 A g –1 ) and superior cycling stability (88% capacitance retention of the initial after 60,000 cycles). The well-designed α-K 0.2 MnTi 0.07 O 0.8 -based supercapacitor device exhibits an energy density of 25.16 Wh kg –1 at 1600 W kg –1 . The morphological electrode-structured designer could be a promising attempt for applications in energy-related fields and even beyond power and storage sources.