A Novel High-Performance Anode Material with an Enlarged Potential Window for a Hybrid Energy Storage System

Cobalt-iron (CoFe) layered double hydroxides (LDHs) have received much interest for supercapacitors (SCs) because of their ion-insertable layer structure. However, there is still a need for more effort to increase their potential window and overall electrochemical energy storage capability as SC electrodes. In this work, we present a straightforward approach to synthesizing CoFe-LDHs on zinc oxide seeded carbon cloth (ZnO@CC) via a one-step hydrothermal reaction; the obtained electrode is denoted as CoFe-LDH@ZnO@CC. The electrochemical energy storage properties of CoFe-LDH@ZnO@CC are tested as an anode material using a three-electrode setup for SC applications in 1 M Na₂SO₄ electrolyte. It can operate in a wider potential window reaching up to 1.6 V, exceeding most previously reported anode materials. The CoFe-LDH@ZnO@CC displayed capacitive charge storage accounting for 76% of the total charge stored at 20 mV/s. The CoFe-LDH@ZnO@CC anode delivered a maximum capacitance of 299.8 F/g at 2 A/g, outstanding cycle stability, and retained 97.7% of the initial capacitance value for 5000 cycles at 16 A/g. This study introduces a new strategy for structurally designing electroactive materials for energy storage devices, which might be useful as an anode for SCs.