Incomplete Sulfuration of Ternary NiCoAl LDHs Electrodeposited on Ni Foam: An Effective Strategy to Prepare High-Performance Binder-Free Electrodes for Hybrid Supercapacitors

Battery-type (faradaic) electrode materials with high specific capacity for constructing hybrid supercapacitors are required for energy storage. In this study, a binder free electrode (denoted S-NiCoAl LDHs/NF) was successfully prepared via a facile two-step strategy, including a first electrodeposition of ternary NiCoAl LDHs on Ni foam and the subsequent sulfuration via a solvothermal method. The XRD, EDS mapping, and XPS data showed that the S-NiCoAl LDHs/NF are mainly composed of NiS, Ni3S2, NiCo2S4, and NiCoAl LDHs. SEM and TEM further revealed their porous interconnected ball-flower-like morphology on Ni foam. The S-NiCoAl LDHs/NF electrode displays a high specific capacity of 2.44 C cm(-2) at a current density of 2 mA.cm(-2), good rate capability, and cycle stability. A hybrid supercapacitor using S-NiCoAl LDHs/NF as the cathode and active carbon (AC/NF) as the anode was fabricated, showing the practicality of S-NiCoAl LDHs/NF in energy storage devices. This work provides an effective design philosophy and an efficient method for preparing high-performance battery-type electrodes. (C) 2019 The Electrochemical Society.