RGO-Protected Electroless Plated Nickel Electrode with Enhanced Stability Performance for Flexible Micro-Supercapacitors

The ultrastable metal electrodes that can withstand the mechanical deformations of the soft substrates are always essential for the development of flexible supercapacitors. However, the metal electrode physically deposited on the flexible substrate is rigid and delaminated, and the contact interface is easily degraded under the mechanical cycling. The highly flexible and conductive composites with the intermixed metal-polymer structure as electrodes are key to solving the contact problem. In this work, a universal and facile method for flexible micro-supercapacitors (MSCs) with combination of nickel electroless plating (EN) and reduced graphene oxide (rGO) electrodeposition was presented. The so-called surface exchange and ion exchange (SMIE) technique has been employed to prepare the seed layer, and the electroless plating was conducted to deposit the Ni-P layer. The rGO-coated (GC) layer was then electrodeposited onto the Ni-P layer to form an EN/GC composite structure. EN/GC electrodes with symmetric interdigitated electrodes were fabricated at room temperature via an all-solution method. Due to the novel intermixed Ni-polyimide interfacial structure, the highly flexible and mechanically stable EN/GC layer was formed. The introduction of GC enables the composite structure to be highly electrochemically stable. The result indicated that EN/GC electrodes exhibit superior charging and discharging performance without obvious capacitance degradation. The flexible micro-supercapacitors with EN/GC electrodes were also demonstrated and can work after 10 000 cycles of bending tests. The developed technology is compatible with the batch fabrication process and can be used to fabricate MSCs with high electrochemical stability.