High-performance iron ion hybrid supercapacitor based on CoMoS₃/polyaniline electrodes

Energy storage devices fulfill an indispensable and critical role in balancing the supply and demand of energy, reducing the consumption of fossil fuels, and mitigating environmental pollution. In this work, an iron-ion hybrid supercapacitor (IIHS) is developed，which employs a nano-honeycomb structured CoMoS3-PANI composite as the cathode. CoMoS₃ improves the redox active sites for its electrochemical reactions, which helps to prevent the self-stacking of ion transfer channels. The introduction of PANI creates a pillar-supported hierarchical structure for CoMoS₃ growth, which enhances Fe²⁺ ion transport kinetics and cycling stability. Benefiting from this advanced electrode architecture, the assembled alternating current (AC)-based supercapacitor delivers a high areal capacitance of 3065.2 mF cm^-2 at a current density of 1 mA cm^-2 (voltage window: 0-1.2 V). Furthermore, the device exhibits outstanding long-term cycling stability, maintaining 88.19% of its initial capacitance after 10,000 galvanostatic charge-discharge cycles. Meanwhile, we fabricated poly (vinyl alcohol) / carboxymethyl cellulose Fe²⁺ gel electrolyte, and the flexible device maintained 84.28% capacity after 3000 cycles. This cost-effective, long-lasting, and safe iron ion hybrid capacitor holds significant promise for future applications in the energy storage sector.