Synergistic enhancement of pseudocapacitance behavior in supercapacitors through porous carbon and lignosulfonate integration

The growing energy crisis has intensified the need for efficient energy storage solutions. Biomass has emerged as a promising resource for novel energy storage devices. Lignosulfonate, a byproduct of the forestry and pulp industries, contains quinone groups and has enormous potential for electrochemical energy storage. However, due to its poor electrical conductivity, this material must be combined with conductive materials to improve the energy storage efficiency. Carbon materials, particularly porous carbon, are ideal conductive substrates because of their high electrical conductivity, affordability, and ease of fabrication. This study demonstrates the synergistic effects of lignosulfonate/nanocarbon composites (LS/NC), in which heteroatom doping, high specific surface area, and quinone groups considerably enhance their electrochemical performance. Nanocarbon (NC) provides ion diffusion channels with low internal resistance and a large double-layer reaction area, promoting efficient electrolyte ion diffusion and transport. In addition, the introduction of oxygen and sulfur heteroatoms not only increases the material's hydrophilicity but also provides polar surfaces and accessible pseudocapacitive sites. Under acidic conditions, the LS/NC composite achieved a specific capacitance of 571 F g−1 at a discharge rate of 1 A g−1—approximately double that of NC alone (279 F g−1). These findings provide notable advancements in the development of efficient energy storage devices.