Corrosion-controlled surface engineering improves the adhesion of materials for stable free-standing electrodes

Directly anchoring active materials on porous conductive substrates is considered an effective strategy to obtain a high-activity electrode since the direct contact between active materials and substrates benefits charge transfer, and the presence of porous structures provides more active sites. However, due to the presence of strong stress and weak adhesion, active materials loaded on the substrate are very easy to peel off during assembly and use, which can greatly shorten the lifetime of use. Herein, an ultrasonic corrosion strategy is proposed to regulate the surface of a metal substrate. We find that ultrasonic oxygen corrosion and interfacial water control play key roles in fabricating the complex electrode, which can help the surface of Cu foam to form special lamellar cross-linked CuO nanoarchitectures with strong adhesion and then overcome the defect of the deposited NiCo layered double hydroxides (NC LDH) on the stress and adhesion. The expected electrode shows more than 70% improvement in cycling stability at an ultra-high current density of 20 A g^-1, relative to the active material layer of the electrode with strong stress and weak adhesion. Meanwhile, benefiting from its lamellar cross-linked nanoarchitectures having large specific surface area and many nano-pores, it presents a high specific capacitance of 3010.8F g^-1 at 1 A g^-1 and a good rate capability of 59.3% at 50 A g^-1. It is foreseen that this finding provides a novel, universal strategy for managing the surface and interface of the metal substrate, thereby obtaining a reliable, stable electrode.