3D Controlled Growth of Binder‐Free Manganese Ferrite Electrodes for High‐Performance Hybrid Supercapacitor Device

Abstract The remarkable electrochemical features and promise for improved performance of binder‐free manganese ferrite have attracted a lot of research interest in hybrid energy storage devices. The fine‐tuning of preparative parameters has a significant impact on energy‐storing performance, with deposition time appearing as a crucial parameter in enhancing their electrochemical properties. This work offers a simple and scalable method for the preparation of manganese ferrite with varying deposition times using chemical bath deposition (CBD). Varying deposition time results in a transformation from the manganese ferrite hydrate (MnFe ₂ O ₄ .H ₂ O) to manganese ferrite (MnFe ₂ O ₄ ) cubic structure and alteration in morphology from tetrahedral crystals to octahedral‐like in MnFe ₂ O ₄ series thin films (C‐MFO). The MnFe ₂ O ₄ electrode with an optimal deposition time of 7 h (C‐MFO3) sample, featuring a cube‐like morphology, achieves a maximum specific capacitance ( C s) of 491.2 F g ⁻¹ at 1.5 A g ⁻¹ , maintaining 81.1% retention. Furthermore, the constructed hybrid supercapacitor device (HSD) exhibits a high C s of 73.3 F g ⁻¹ , along with a specific energy (SE) of 36.7 Wh kg ⁻¹ at a specific power (SP) of 1.7 kW kg ⁻¹ . This work introduces a scalable method for producing binder‐free manganese ferrite electrodes, suitable for use as cathodes in hybrid energy storage devices for practical applications.