High-Performance Asymmetric Supercapacitors Assembled from La-Doped ZnCo₂O₄/MnCo-LDH Nanoflower Positive 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.