Reduced graphene oxide-modified Ni-Co phosphate nanosheet self-assembled microplates as high-performance electrode materials for supercapacitors

It is demonstrated that the incorporation of reduced graphene oxide (rGO) and pseudocapacitance materials often offer an effective strategy toward fast reversible redox reactions while remaining their high pseudocapacitance. In this work, a type of rGO-modified Ni-Co phosphates (Ni(Co)NH4PO4@rGO) microplates were fabricated for supercapacitors electrodes via a one-step hydrothermal method. SEM and TEM tests indicated that the obtained microplates are comprised of well-aligned crystalline Ni(Co)NH4PO4 nanosheets. Moreover, the rGO-modified microplates exhibit a high specific capacitance of 1020 F g−1 at 1 A g−1, which is 16.3% enhanced compared to that of the untreated Ni(Co)NH4PO4) ones (877 F g−1). While the rate capacitor can reach to 92%. Furthermore, it is observed that after 700-cycles, the specific capacitance can increase to their maximum value of 1451 F g−1 at current density of 10 A g−1, and can still remain 1275 F g−1 after 5000 cycles, showing a high cycling stability. The Ni(Co)NH4PO4 showed the same tendency but the low values. These excellent electrochemical performances could be due to rGO modification and self-assembled well-aligned nanosheets. This type of structures cannot only facilitate the transfer electrons, but also offer high electrochemical activity sites and short transport path length for electrolyte ions.