Prussian-Blue-Analogue-Derived Ag@Co₃O₄ and Bi₂O₃@BiFeO₃ Nanostructures As Battery-Type Electrodes for High-Performance Asymmetric Supercapacitor

The reasonable construction of Prussian blue analogue (PBA) derivative electrode materials with unique structural characteristics and multiple redox active sites has attracted extensive attention in the field of energy storage. Herein, the battery-type electrodes of silver-decorated cobaltosic oxide (Ag@Co 3 O 4, denoted as Ag3@CO) and bismuth–iron oxide (Bi 2 O 3 @BiFeO 3, denoted as BO@BFO) have been proposed by an in situ oxidation strategy of PBAs. It is surprising that the silver nanoparticles of Ag3@CO are uniformly distributed in the cobalt oxide phase, further improving its electrical conductivity and accelerating the electron transfer rate. The irregular rod nanostructure of BO@BFO enhances its reaction kinetics by augmenting the interfacial contact area. Furthermore, the integration of binary metals not only offers numerous redox reaction centers but also heightens synergistic effects of pseudocapacitive dominated multielectron phase conversion, resulting in enhanced capacity and rate capability. The optimized Ag3@CO cathode material exhibits a discharge-specific capacity of up to 1027 C g –1 at a current density of 1 A g –1, maintaining an impressive rate of 82.77% despite the high current density of 10 A g –1 . In addition, the BO@BFO offers a capacity of 615 C g –1 and is utilized as an anode to establish an asymmetric solid-state supercapacitor (ASC). Notably, the assembled Ag3@CO//BO@BFO ASC device within a voltage window of 1.8 V has achieved an energy density of 55 Wh kg –1 at a power density of 1640 W kg –1; moreover, the fully charged device can light up a red LED and drive a small electric fan, demonstrating its potential in practical applications. This work underscores the immense potential of PBA derivative materials of Ag@Co 3 O 4 and Bi 2 O 3 @BiFeO 3 for driving high-performance ASC technology forward.