Effects of high-shear mixing and the graphene oxide weight fraction on the electrochemical properties of the GO/Ni(OH)₂ electrode

Abstract

A high-shear mixer was used in the process of chemical precipitation to prepare graphene oxide (GO) and Ni(OH)2 composites with different weight fractions of GO from 0 wt% to 2.6 wt%. The GO/Ni(OH)2 composite with 1.5 wt% GO prepared by high-shear mixing (1.5GO/Ni(OH)2-H) displayed a high specific capacitance (1836 F g-1 at 2 mV s-1), which was beyond that (1581 F g-1 at 2 mV s-1) of GO/Ni(OH)2 obtained by impeller agitator stirring (1.5GO/Ni(OH)2-M). 1.5GO/Ni(OH)2-H also showed excellent cycling stability, retaining 91.7% of its initial specific capacitance after 2000 cycles. Furthermore, the asymmetric device (the 1.5GO/Ni(OH)2-H as the positive electrode and active carbon as the negative electrode) exhibited a high energy density of 41.2 W h kg-1 at a power density of 1500 W kg-1 with a voltage of 1.5 V. In addition, the effects of high-shear mixing and impeller agitator stirring on the microstructures and electrochemical properties of the composites were discussed, which indicated that high-shear mixing could exfoliate graphene oxide and restrain the grain growth of Ni(OH)2, thus leading to excellent electrochemical performance.