Nickel-cobalt layer double hydroxide @ lignin-based hollow carbon quasi core-shell structure for high-performance supercapacitors

Abstract

The physicochemical properties of an advanced supercapacitor electrode material can be co-tailored by incorporating various active materials into a hierarchical micro-/nano-architecture with a core-shell structure. Herein, we presented the development of high-performance supercapacitor electrode materials of quasi core-shell architectures based on nickel-cobalt layered double hydroxides supported on lignin-based hollow carbon (NiCoLDH@LHC) nanocomposites. The synthesis involves a novel approach combining enzymatic hydrolysis lignin (EHL) as a carbon source and magnesium oxide (MgO) as a template, utilizing evaporation-induced self-assembly (EISA) followed by carbonization. The manipulation of the mass ratio of NiCoLDH/LHC can induce alterations in its apparent morphology, stratified porosity, and active site, thereby an influence on its electrochemical performance. The optimal NiCoLDH@LHC90 nanocomposites display a unique flower-like spherical structure with open pores, a substantial specific surface area (SSA), and numerous electrochemically active sites. In addition, the density functional theory (DFT) calculations demonstrate that the higher density of Ni3+/Co3+ cations induced by the incorporation of LHC can increase the conductivity of NiCoLDH materials. Notably, these nanocomposites exhibit a remarkable specific capacitance of up to 640 C g−1 at 1 A g−1, with exceptional cycling stability (93.66% retention over 10,000 cycles). Furthermore, an assembled NiCoLDH@LHC90//LHC asymmetric supercapacitor demonstrates an impressive energy density (power density) of 35.44 Wh kg−1 (200.01 W kg−1). The physicochemical properties of an advanced supercapacitor electrode material can be finely tuned by incorporating various active materials into a hierarchical micro-/nano-architecture with a core-shell structure.