Excellent electrochemical stability of graphite nanosheet-based interlayer for electric double layer capacitors

Abstract

Characterized by high power density and long cycle life, electric double layer capacitors have been considered to be most promising energy storage devices. However, the use of low electrolyte concentration due to the degradation of current collector in high electrolyte concentration involves their limitation for ionic diffusion at high current densities during cycling, leading to a low electrochemical behavior. Therefore, the sensible design of the interfacial structure between the current collector and the active material is a supreme technology for accomplishing desired requirements as the improved performance of current collector. In the present paper, by applying the graphite nanosheet as an interlayer on the nickel (Ni) current collector, the electrochemical performance is improved with high specific capacitance (236 F g−1 at the current density of 0.2 A g−1), outstanding high-rate ability (87%), and excellent cycling stability (93% after 10,000 cycles in the high-concentration electrolyte). Hence, the advantages of this unique approach include the improvement of the contact area between the current collector and the active material and prevention of the oxidation of the Ni current collector. This enhanced electrochemical performance suggests that this interface engineering is a powerful strategy for potential applications in electric double layer capacitors.