Lignin nanoparticles-based carbon aerogels with 3D interconnected framework supported nickel-cobalt layered double hydroxide nanosheets for high-performance hybrid supercapacitors

Renewable biomass-based carbon materials are increasing recognized as a promising alternative for energy storage devices due to their high specific surface area, excellent conductivity, unique chemical stability, low cost, and abundant sources. Herein, we first propose the fabrication of a composite material consisting of nickel-cobalt layered double hydroxides (Ni/Co LDHs) nanosheets supported by lignin nanoparticles (LNPs)-based carbon aerogels (LCA). This composite material features a distinctive nanostructure that combines a 3D interconnected framework of microporous LCA host with well-defined 2D ultrathin Ni/Co LDHs nanosheets. The molar ratio of Ni/Co in the solution was controlled to achieve this structure. The LCA@LDHs-2 electrode, with a molar ratio of Ni/Co of 1:2, demonstrated a specific capacity of 861C g- 1 at a current density of 0.5 A g- 1 and maintained a high specific capacity of 752C g- 1 even at 20 A g- 1 , as well as an exceptional cyclic stability of 98.5 % and coulombic efficiency of 100 % over 10,000 cycles. The assembled asymmetric supercapacitor (ASC) device using LCA@LDHs-2//LCA exhibited a high specific capacity of 499C g- 1 at 0.5 A g- 1 and retained a capacity of 260C g- 1 at 10 A g- 1 . This ASC device also achieved maximum energy and power densities of 53.3 W h kg- 1 and 9998 W kg- 1 , respectively. Furthermore, the integrated LCA@LDHs, when used as a battery-type cathode material for supercapacitors, displayed hybrid electrochemical behaviour involving both capacitive and diffusive contributions to charge storage, showcasing outstanding capacitance performance and cycling stability. This study introduces a novel approach for the large-scale production of high-performance electrode materials derived from biomass for practical supercapacitor applications.