A novel fabricated conductive substrate for enhancing the mass loading of NiCoLDH nanosheets for high areal specific capacity in hybrid supercapacitors

Abstract

Nickel foam (NF), as an excellent conductive substrate, is usually applied to the preparation of electrodes. However, the surface of nickel foam is too smooth to increase the loading of active materials. In this work, a facile method is developed to improve the mass loading of NiCo-layered double hydroxide nanosheets (NiCoLDH NSs) by directly vulcanizing nickel foam. The Ni3S2 nanocone formed on the surface of nickel foam (Ni3S2@NF) is characterized by XRD, XPS and SEM. The obtained NiCoLDH@Ni3S2@NF-480 using Ni3S2@NF as substrate possesses high NiCoLDH areal mass loading of 4.0 mg cm−2, which is far above that of NiCoLDH@NF-480 using pure NF as substrate (0.2 mg cm−2). Accordingly, the NiCoLDH@Ni3S2@NF-480 electrode displays a high specific capacity of 2.021 C cm−2 under the current density of 1 mA cm−2. It also presents excellent cycling stability with 92% of capacity retention after 5000 times cycles. The hybrid asymmetric supercapacitor (NiCoLDH@Ni3S2@NF-480//nitrogen-doped mesoporous carbon) exhibits a high volumetric energy density of 0.52 mW h cm−3 and high power density of 32 mW cm−3. This work may provide a new substrate for fabricating the high mass loading electrode in energy storage device.