Co2+-doped spindle-like Fe2O3 derived from metal-organic framework: Enhanced energy storage for high-performance asymmetric supercapacitors

The high theoretical specific capacity and natural abundance of Fe 2 O 3 render it an appealing choice for utilization as an anode material in asymmetric supercapacitors (ASCs). The material's path to practical adoption, however, is plagued by inherent limitations, including low intrinsic conductivity and substantial volume variation during charge-discharge processes. To overcome these issues, this work synthesized a Co 2+ -doped Fe 2 O 3 composite (CMF) using a metal-organic framework (MOF) as a sacrificial template. The MOF-derived Fe 2 O 3 possesses a highly ordered and tunable pore architecture, thereby enabling swift diffusion and migration of electrolyte ions. Furthermore, introducing Co 2+ into the Fe 2 O 3 lattice generates many oxygen vacancies and crystal defects, greatly boosting its intrinsic conductivity, ion migration, and structural stability. Electrochemical characterization demonstrated that the optimized 2 wt% CMF electrode yielded a high specific capacity of 226.1 mAh g −1 at 1 A g −1 . When configured into an AC//2 wt% CMF asymmetric supercapacitor, the device recorded an energy density of 43.1 Wh kg −1 at a power density of 350 W kg −1 . Notably, the assembled device also exhibited outstanding cycling durability, retaining 96.4% of its initial capacity after 20,000 cycles at 2 A g −1 . The practical capability of the device was demonstrated by powering a light-emitting diode (LED), highlighting its potential for real-world applications.