Magnetically Induced Ordered Structure-Assisted Defect Engineering Strategy for High-Performance All-Pseudocapacitive Film Supercapacitors.

Film supercapacitors, due to their light weight and good flexibility, are ideal power sources for wearable electronic devices. However, due to the limited research on pseudocapacitive film electrode materials, achieving high energy density for film supercapacitor remains a challenge. Here, the film anode (Fe@Fe3O4/CNTs) and cathode (NiCo-NiCo compound/CNTs) were prepared by the vacuum filtration technology. Density functional theory calculations combined with experimental results revealed that oxygen vacancies can induce the formation of dense localized charge aggregation regions at the Fe/Fe3O4 interface, significantly enhancing the charge transfer rate in electrochemical reactions, enabling the anode to achieve a specific capacity of 7.88 F cm-2 (749.1 C g-1) at a high mass loading of 16.7 mg cm-2. Meanwhile, after introducing oxygen vacancies, the adhesion energy at the interface significantly increased, enhancing the binding strength between Fe and Fe3O4, making it less prone to peeling due to current shock during long-term charge and discharge cycles, thereby improving the cycling stability of the Fe-based anode (76% capacitance retention after 20 000 cycles). The all-pseudocapacitive film supercapacitor successfully assembled obtains an excellent energy density of 1.362 mWh cm-2 (122.5 Wh kg-1) at a total mass loading of 27.8 mg cm-2, far exceeding previously reported values.