Boosting high-performance sodium-ion storage of MnO2 via single-site defects and crystalline/amorphous interface engineering

Sodium-ion hybrid supercapacitors, as emerging energy storage devices, require structural optimization of electrode materials for performance enhancement. This study employs a facile one-step hydrothermal synthesis to construct Ru/MnO 2 electrode materials featuring single site defects and crystalline-amorphous heterointerfaces, elucidating the synergistic mechanism of dual structural features on sodium storage properties. Aberration-corrected high-resolution transmission electron microscopy verifies the atomic-level dispersion of single site defects. High-resolution transmission electron microscopy unambiguously reveals the ubiquitous distribution of crystalline-amorphous heterointerfaces within the Ru/MnO 2 electrode. Electrochemical evaluations demonstrate that the composite electrode delivers a remarkable specific capacitance of 377.6 F g −1 at 1 A g −1 , demonstrating a 75.2 % enhancement compared to conventional manganese oxide counterparts (215.5 F g −1 ). The corresponding device achieves a peak energy density of 59.6 Wh kg −1 while maintaining 93 % capacity retention after 10,000 cycles at 10 A g −1 . This work proposes a novel structural engineering paradigm for advancing high-performance sodium-ion energy storage systems through defect-interface synergy.