Construction of Binder-Free, Self-Supported, Hetero-Core-Shell Honeycomb Structured CuCo 2 O 4 @Ni 0.5 Co 0.5 (OH) 2 with Abundant Mesopores and High Conductivity for High-Performance Energy Storage.

Clever and rational design of structural hierarchy, along with precise component adjustment, holds profound significance for the construction of high-performance supercapacitor electrode materials. In this study, a binder-free self-supported CCO@N 0.5 C 0.5 OH/NF cathode material is constructed with hierarchical hetero-core-shell honeycomb nanostructure by first growing CuCo 2 O 4 (CCO) nanopin arrays uniformly on highly conductive nickel foam (NF) substrate, and then anchoring Ni 0.5 Co 0.5 (OH) 2 (N 0.5 C 0.5 OH) bimetallic hydroxide nanosheet arrays on the CCO nanopin arrays by adjusting the molar ratio of Ni(OH) 2 and Co(OH) 2 . The constructed CCO@N 0.5 C 0.5 OH/NF electrode material showcases a wealth of multivalent metal ions and mesopores, along with good electrical conductivity, excellent electrochemical reaction rates, and robust long-term performance (capacitance retention rate of 87.2%). The CCO@N 0.5 C 0.5 OH/NF electrode, benefiting from the hierarchical structure of the material and the exceptional synergy between multiple components, demonstrates an excellent specific capacitance (2553.6 F g -1 at 1 A g -1 ). Furthermore, the assembled asymmetric CCO@N 0.5 C 0.5 OH/NF//AC/NF supercapacitor demonstrates a high energy density (70.1 Wh kg -1 at 850 W kg -1 ), and maintains robust capacitance cycling stability performance (83.7%) after undergoing 10 000 successive charges and discharges. It is noteworthy that the assembled supercapacitor exhibits an operating voltage (1.7 V) that is well above the theoretical value (1.5 V).