Layered materials provide good electrochemical performance, but insufficient rate capability, which is the main issue in energy storage. Herein, we propose a facile synthesis of Co2(CO3)(OH)2 nanoflakes and polyhedron flowers supported on Ni foam, a novel binder-free electrode. Power law revealed that Co2(CO3)(OH)2 stores charge by a battery-type mechanism at the peak potential. The nanoflakes store more internal surface charge than the polyhedron-flower, which was confirmed via Trasatti plot. Benefiting from amorphous nanostructure, unique morphology and high surface area, the nanoflakes shows good performance. The areal capacitance (2111 mF cm−2), rate capability (80%), and energy density (0.152 mWh cm−2) are comparable to recent reports. The results suggest that the amorphous Co2(CO3)(OH)2 nanoflakes are a suitable cathode candidate for the supercapattery. The assembled supercapattery (ASC) provides high specific capacitance (91 F g−1), high energy density (26.22 Wh kg−1 at power density 828 W kg−1), and long cycle life (specific capacitance retention of 85% over 4000 cycles). The ASC device shows good potential in the field of energy storage devices.