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