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

Abstract

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.