Mn3O4/reduced graphene oxide based supercapacitor with ultra-long cycling performance

Abstract

In this work, highly stable Mn₃O₄ nanoparticles were synthesized via an air oxidation procedure with the aid of an anionic surfactant, which showed durable performance with 100% capacitance retention after 10 000 cycles in 1 M Na₂SO₄. An annealed film was subsequently fabricated in which the nanostructured Mn₃O₄ was uniformly intercalated between reduced graphene oxide (RGO) sheets. To complement the Mn₃O₄/RGO film, a hybrid film consisting of RGO and carbon nanotubes was employed as the negative electrode. Benefiting from the thermodynamically stable Mn₃O₄ nanoparticles, specific layered structural design, and highly conductive RGO scaffolds, the assembled supercapacitor exhibited a high volumetric capacitance of 52.2 F cm⁻³ at 0.2 A cm⁻³, which translated to remarkable volumetric energy and power density (18 mW h cm⁻³ and 3.13 W cm⁻³). More importantly, the assembled device was able to demonstrate an outstanding cycling performance of 115% capacitance retention after 60 000 cycles. The bottom-up approach proposed in this study involving the synthesis of durable nanoparticles followed by composite construction could pave the way towards designing ultra-stable supercapacitors as next-generation energy storage devices.