ZIF-67-assisted construction of hollow core/shell cactus-like MnNiCo trimetal electrodes and Co, N dual-doped carbon electrodes for high-performance hybrid supercapacitors†
The successful design of a hybrid supercapacitor with high power and energy density is mainly based on innovative materials and unique structures. Herein, self-supported Ni–Co(CO3)0.5(OH)·0.11H2O@MnNiCo–OH (Ni–CCH@MnNiCo–OH) with a hollow core/shell cactus-like structure was synthesized as a battery-type positive electrode and KOH-activated ZIF-67 derived Co, N dual-doped hierarchical ZIF-67-C-KOH was prepared as a capacitive-type negative electrode. Benefiting from the optimized ZIF-67-template modification and polymetallic co-deposition tactics, the positive electrode exhibits an outstanding specific capacity of 8.2 C cm−2 at 1.5 mA cm−2 (1029.3 C g−1 at 1 A g−1) and an impressive cycling retention of 88% after 3000 cycles at 20 mA cm−2, which are better than those of Ni–Co3O4@ZIF-67-Co3O4, Ni–CCH@NiCo–OH and Ni–CCH@MnCo–OH electrodes. Likewise, ZIF-67-C-KOH profits from the nitrogen-rich and porous properties of the precursor and can attain a specific capacitance of 262.4 F g−1 at 1 A g−1 as well as an excellent rate performance of 82% at 10 A g−1. The assembled Ni–CCH@MnNiCo–OH//ZIF-67-C-KOH hybrid device has a maximum voltage window of 1.8 V and achieves a specific capacitance of 187.3 F g−1 at 1 A g−1, a high energy density of 84.29 W h kg−1 at a power density of 900 W kg−1 as well as a fantastic stability up to 5000 cycles (74.91% retention at 2 A g−1), showing enormous potential in energy-storage applications.