Rational design of cobalt-iron bimetal layered hydroxide on conductive fabric as a flexible battery-type electrode for enhancing the performance of hybrid supercapacitor

Mixed metal hydroxide (MMH) based supercapacitor electrodes, with their outstanding performance from the synergistic effect originating from mixed metallic elements, can effectively address the drawbacks of single metal hydroxide (SMH) based electrodes. Owing to their superior electrochemical properties stemming from their unique structural and chemical compositional design, MMH electroactive materials have attracted considerable attention for energy storage devices. Among those devices, a layered double hydroxide (LDH) structure has been emerged as an alternative electrode due to its large interlayer arrangement, high redox activity, and multiple oxidation states. Herein, we have successfully designed cobalt-iron LDH nanosheets (CoFe LDH NSs) on nickel fabric by a facile electrochemical deposition (ECD) method with a chronoamperometry voltage of − 1.0 V for 100 s. Further, the unique as-fabricated structure that arises from the tunable chemical composition and wide variety of material properties was successfully manipulated to boost the electrochemical energy storage performance. Finally, the optimized electrode made of Co0.5Fe0.5 exhibited superior electrochemical performance due to its porous, surface-stimulated large electroactive area and high conductivity with great stability. By integrating a battery-type electrode of CoFe LDH and a capacitive-type electrode of activated carbon (AC), a hybrid supercapacitor (HSC) device was assembled. Besides, the high areal capacitance of 70 µF/cm2, it delivers high energy density (1.6 mWh/cm2) and power density (0.09 mW/cm2) values along with the excellent cycling stability (91% capacity retention). Moreover, the fabricated flexible device offers the significance as a power source in flexible electronic devices with its high degree of flexibility originated from flexible substrate. This work not only provides a promising electrode for supercapacitors, but also a unique structural and compositional design of electroactive materials for energy storage systems.