Performance Improvement of Supercapacitor Materials with Crushed 3D Structured Graphene

Abstract

Electrochemical capacitor devices with conventional 2D-graphene sheets (2D-rGO) often demonstrate poor performance, especially in cyclability due to the lamellar stacking and agglomeration of the electrode materials. Herein, we have proposed that crushed 3D-graphene (c-3D-rGO) can overcome the limitations. A simplistic way to prepare 3D-crushed graphene structures has been presented utilizing metal rGO core–shell (Ni@rGO) followed by acid leaching. The electrochemical performances of the prepared c-3D-rGO were evaluated as capacitor material using a three-electrode system with aqueous 0.5 M Na2SO4 solution through cyclic voltammetry and galvanostatic charge-discharge measurements. In addition, 2D-rGO was separately prepared to compare the performance with 3D-crushed graphene structures. It has been observed that the calculated specific capacitance (C sp) value of the prepared c-3D-rGO was 335 Fg−1 at a current density of 0.15 Ag−1, which was about three times higher than that of the 2D-rGO. Furthermore, the c-3D-rGO electrode retained 100% capacitance of its initial value after 10000 cycles, demonstrating the material’s excellent electrochemical stability. Again, to show the performance in hybrid capacitors, manganese oxide (MnOx) was incorporated onto 2D-rGO and c-3D-rGO. The presence of MnOx significantly improved the capacitive performance of 2D-rGO and c-3D-rGO. The C sp value (532 Fg−1) of the prepared 3D-rGO/MnOx was much higher than that of 2D-rGO/MnOx (284 Fg−1) at a current density of 0.15 Ag−1. The c-3D-rGO/MnOx composite materials also showed good cyclic stability. The high-performance of the c-3D-rGO could be correlated with the structural features of uneven defects and 3D-voids present in the material, which maintained a low level of aggregation. This study is expected to broaden the application of graphene for commercial use.