Novel bowl-like or capped carbon with a low carbon footprint as electrode material in EDLCs

Large surface area, excellent electrical conductivity, homogeneous structure, and extended cycling stability are desirable characteristics for energy materials. Carbon-derived structures exhibit porous structure, work well in a wide potential window, and are highly conductive. Hence, they can show enhanced rate capability and cycle life. Despite ongoing efforts, the synthesis of carbons at lower temperatures remains a challenge. In comparison, the high-temperature synthesis protocols lead to a high CO₂ footprint. Here, we report the synthesis of unique carbon morphologies, namely capped carbon nanostructures (CCS) and bowl-like carbon structures (BCS). Their performances are either comparable or higher than those conventionally used morphologies of carbon, such as nanospheres, microspheres, nanotubes, graphene oxide, and layered structures. The four-sided opening in BCS particles ensures higher adsorption of electrolyte ions, which is even higher than hierarchical or spherical structures. The cap formation on the CCS acts like an additional layer on top of the sphere. Further, the CCS is arranged in a sequential honeycomb array, which leads to the formation of definitive channels for electrolyte diffusion. The unique carbon morphologies showed nearly ∼ 40 % increment in the specific capacitance values compared to other commonly used carbon structures. The novel morphologies also have a much lower carbon footprint, as shown by the life cycle assessment (LCA) studies.