Though redox-based electrode materials with a high surface-area are expected to bridge the gap between supercapacitors and rechargeable batteries in energy-storage applications, full utilization of the inherent electoactivity is frequently hindered by the limited diffusion of electrolytes, paricularly during high-rate charge/discharge. Here, we demonstrate the electrochemical properties of Ni(OH)2 nanoplatelets that are vertically grown on graphene by employing poly(amidoamine) dendrimers as growth directing agents and as linkers. By virtue of the structural features, Ni(OH)2 electrodes deliver a maximum specific capacity of 1226 Cg−1 (2043Fg−1) at 5mVs−1. The electrodes also retain a substantial capacity at high charge/discharge rates (955Cg−1 at 1Ag−1 vs. 560Cg−1 at 80Ag−1). The cycability is also remarkable, exhibiting the capacity retention of 102% after 5000 cycles at 10Ag−1. These excellent electrochemical properties are contrasted with those of a composite prepared without dendrimers (496Cg−1 at 5mVs−1; 486Cg−1 at 1Ag−1 vs. 184Cg−1 at 80Ag−1; 78% retention). By virtue of Ni(OH)2 nanoplatelets, an asymmetric full-cell coupled with a graphene electrode can deliver one of the highest energy densities ever reported (52–58Whkg−1) with high power densities that range between 1.0 and 20.0kWkg−1.