High-Performance Asymmetric Supercapacitors Assembled from La-Doped ZnCo2O4/MnCo-LDH Nanoflower Positive Electrodes and Ti-Supported Sb-Doped SnO2 Negative Electrodes

Transition-metal oxide/layered double hydroxide (LDH) electrodes often suffer from insufficient utilization of active sites, sluggish electron/ion transport, and limited cycling stability at high rates. Here, La-doped ZnCo2O4/MnCo-LDH nanoflowers serve as the positive electrode and Ti-supported Sb-doped SnO2 (Ti/Sb-SnO2) serves as the negative electrode for constructing an asymmetric supercapacitor. A stepwise hydrothermal route, La-doping regulation, and ethylenediamine-assisted morphology control transform stacked nanosheets into open porous nanoflowers with a specific surface area of 382.5 m2 g−1, thereby exposing more electroactive sites and shortening OH− diffusion pathways. La3+-induced lattice distortion and defect-related oxygen species further tune the electronic structure and improve interfacial charge-transfer kinetics. The optimized La-ZnCo2O4/MnCo-LDH electrode delivers 2130 F g−1 at 1 A g−1 and retains 1993 F g−1 after 10,000 cycles at 3 A g−1. The Ti/Sb-SnO2 negative electrode provides 673 F g−1 at 1 A g−1 and 302 F g−1 at 15 A g−1. The assembled device operates stably from 0 to 1.8 V in 2 M KOH and achieves 69 Wh kg−1 and 13,500 W kg−1.