LAUSR

Abstract An easily-operated and inexpensive strategy (pencil-drawing–electrodeposition–electro-oxidation) is proposed to synthesize a novel class of multilayer core–shell structured composite paper electrode, which consists of copper, cuprous oxide and graphite assembled on cellulose fibers. This interesting electrode structure plays a pivotal role in providing more active sites for electrochemical reactions, facilitating ion and electron transport and shorting their diffusion pathways. This electrode demonstrates excellent electrochemical properties with a high specific capacitance of 601 F g−1 at 2 A g−1 and retains 83% of this capacitance when operated at an ultrahigh current density of 100 A g−1. In addition, a high energy density of 13.4 W h kg−1 at the power density of 0.40 kW kg−1 and a favorable cycling stability (95.3%, 8000 cycles) were achieved for this electrode. When this electrode was assembled into an asymmetric supercapacitor with carbon paper as negative electrode, the device displays remarkable electrochemical performances with a large areal capacitances (122 mF cm−2 at 1 mA cm−2), high areal energy density (10.8 μW h cm−2 at 402.5 μW cm−2) and outstanding cycling stability (91.5%, 5000 cycles). These results unveil the potential of this composite electrode as a high-performance electrode material for supercapacitors.