In situ construction of core–shell structured cobalt oxide@nickel–cobalt-layered double hydroxide nanorods with abundant oxygen vacancies towards boosting electrochemical energy storage

Abstract

In pursuit of high-performance supercapacitors (SCs) with exceptional electrochemical capacitive properties, the logical design of sophisticated architectures composed of multiple modules presents a crucial challenge. Herein, a facile in situ “growth–conversion–oxidation” route is designed to obtain a core–shell structured nanorod-like CoO@NiCo layered double hydroxide (LDH) with abundant oxygen vacancies on a Ni foam substrate (NCLO) for high performance supercapacitors. Density functional theory (DFT)-based computations reveal that NCLO has an enhanced density of states (DOS) in the vicinity of the Fermi energy level suggesting an increased electrical conductivity attributed to the existence of oxygen vacancies in NCLO. Notably, NCLO displays an impressive specific capacitance of 333.3 mA h g⁻¹ (2264.2 F g⁻¹ at 1 A g⁻¹). Furthermore, the NCLO//AC asymmetric supercapacitor (ASC) device exhibits an outstanding capacity retention rate of 90.8% following 10 000 cycles and a remarkable energy density reaching up to 63.8 W h kg⁻¹ at 800.0 W kg⁻¹. Our work highlights the feasibility of utilizing vacancy engineering and distinctive structural features as an innovative strategy for achieving energy storage materials with an extraordinary performance.