A superhydrophilic “nanoglue” for stabilizing metal hydroxides onto carbon materials for high-energy and ultralong-life asymmetric supercapacitors

Abstract

Coupling electroactive species with carbon supports to fabricate hybrid electrodes holds promise for high-performance supercapacitors. Nevertheless, the poor compatibility and weak bonding between carbon substrates and electroactive species remain a bottleneck to be tackled. Herein, we present a superhydrophilic “nanoglue” strategy for stabilizing NiCo-layered double hydroxide (NiCo-LDH) nanosheets on inert carbon cloth (CC) by employing a nitrogen-doped (N-doped) carbon layer as the structure/interface coupling bridge to make hybrids (denoted as CC–NC-LDH) for supercapacitors. Such a “nanoglue” on a CC substrate results in the formation of a superhydrophilic surface/interface, which is favorable for the robust and uniform growth of NiCo-LDH on the CC, and helps effectively tune the electronic structural states and results in a strong coupling interaction between the CC and NiCo-LDH nanosheets. Benefiting from these integrated merits, asymmetric supercapacitors fabricated with the CC–NC-LDH hybrids as the positive electrode and typical activated carbon as the negative electrode deliver a high energy density of 69.7 W h kg⁻¹ at a power density of 0.8 kW kg⁻¹, with an ultra-low average capacitance fade rate of ∼0.00065% per cycle within 20 000 cycles at a current density of 10 A g⁻¹. This superhydrophilic “nanoglue” strategy can also be extended to assemble other kinds of active species on different inert substrates, and holds the potential for creating efficient and robust electrode materials for energy-related devices.