Self-grown nickel hydroxide nanosheets on 3D hierarchical porous turtle shell-derived activated carbon for high-performance supercapacitors

Although the capacity of Ni(OH)2 is quite high, the disadvantages such as poor electrical conductivity and severe stacking seriously limit the practical application. Through introduction of turtle shell derived biomass activated carbon (TSHC-5) with hierarchical porous structure as substrate by simple solvothermal method for growth of Ni(OH)2 nanosheets to produce synergistic effect. TSHC-5 provides abundant growth sites for Ni(OH)2, improving interface contact and conductivity. In addition, the 3-D porous structure of TSHC-5 allows for more rapid transport of electrolyte ions, and the stacking during Ni(OH)2 growth is attenuated which exposes more active sites, thus the redox reaction proceeds more rapidly and fully. As a result, the specific capacitance (1752.6F·g−1 at 1 A·g−1) and cycling performance (68.14% after 5000 cycles) of Ni(OH)2/TSHC-5 are demonstrated to be significantly higher compared to that of Ni(OH)2. Moreover, the asymmetric supercapacitor assembled with Ni(OH)2/TSHC-5 achieves an energy density of 58.18 Wh·kg−1 at a power density of 800 W·kg−1, which maintains excellent cycling performance with 74.52% initial specific capacitance retention after 5000 cycles. The excellent electrochemical performance based on Ni(OH)2/TSHC-5 as electrode material allows a broad application in energy storage and energy conversion.