In situ synthesis and morphological evolution of NiCo-LDH@CSC with a 3D nanosheet pore framework for high-performance supercapacitors

Abstract

Asymmetric supercapacitors (ASCs) incorporating layered double hydroxides (LDHs) as electrode materials exhibit excellent capacitance and energy density. However, the inherent poor conductivity and structural instability of LDHs significantly limit their rate capability and lifespan in ASCs. In this study, the synthesis of a novel composite material (NiCo-LDH@CSCx) by in situ growth of LDH on environmentally friendly, corn straw-derived porous carbon (CSC) via a simple hydrothermal process was reported. The optimized NiCo-LDH@CSC0.05 forms well-ordered 3D nanosheet arrays anchored on porous structure, characterized by interlocking pores and nanosheets. This structure enhances electrochemical performance, resulting in a high specific capacity of 195.73 mAh/g (1 A/g), and the capacity still remains in remarkable 89.93 mAh/g at 20 A/g. The assembled ASC, comprising a NiCo-LDH@CSC0.05 positive electrode and a CSC negative electrode, achieves an energy density of 53.7 Wh/kg at 750.1 W/kg and possesses a capacitance retention rate of 89.2% after 10,000 charge–discharge cycles at 5 A/g. Density functional theory analysis results reveal that CSC incorporation upgrades OH− adsorption energy on the electrode surface, improving both capacity and cycling stability. This study presents a cost-effective and scalable approach for designing high-performance ASCs with prolonged operational lifespans.