(603c) Highly Porous Carbon Blacks for Supercapacitors and Electrochemical Energy Storage

Highly porous carbonaceous nanoparticles were prepared by judicious oxidation of a commercial carbon black (CB) grade at 1200 ^oC in a 10 vol % O₂ atmosphere of N₂ (Kelesidis et al., 2022). X-ray diffraction, N₂ adsorption and microscopy analyses revealed that, at these synthesis conditions, O₂ diffuses through and reacts with CB, disordering its crystalline structure. The concurrent external and internal oxidation of CB results in tiny pores that greatly increase the specific surface area, SSA, from 240 up to 2185 ± 199 m²/g. This is about 50 - 100 % larger than the SSA of most porous CB grades that are currently available in the market and on par with that of commercial activated carbons (e.g. YP80) used as active material in supercapacitors or electrochemical double layer capacitors (EDLCs). Most importantly, the gravimetric capacitance of EDLCs made using the above high SSA CB is 40 - 50 % larger than those obtained from EDLCs based on YP80 or Ketjenblack at high scan rates (200 mV/s) and high current densities (Fig. 1). The superior rate performance of the present CB is attributed to the large concentration of pores with 2 - 8 nm radius formed largely by internal oxidation and the small CB particle size (Kelesidis et al., 2024). Hence, close control of the oxidation dynamics of CB can drastically increase supercapacitor performance.

References:

G.A. Kelesidis, N. Rossi, S.E. Pratsinis, Porosity and crystallinity dynamics of carbon black during internal and surface oxidation, Carbon 197 (2022) 334-340, doi.org/ 10.1016/j.carbon.2022.06.020.

G.A. Kelesidis, P. Crepaldi, M. S.E. Pratsinis, Oxidation dynamics of soot or carbon black accounting for its core-shell structure and pore network. Carbon 219 (2024) 118264, doi.org/10.1016/j.carbon.2023.118764.

Figure 1. Cyclic voltammogram of EDLCs made with commercial carbon black (Ketjenblack) or various activated carbons (broken line) in comparison to that obtained here for oxidized CB (solid line) at 200 mV/s.