REVISITING THE CARBON MESOPORE CONTRIBUTION TOWARDS IMPROVED PERFORMANCE OF IONIC LIQUID–BASED EDLCS AT SUB ZERO TEMPERATURES

The important role of mesopores has been investigated in electric double-layer capacitors (EDLCs) operating from 24 °C down to−40 °C by using two in-house synthesized carbons with hierarchical porosity. These carbons were prepared from colloidal nanoparticles of SiO2 as the template and d-glucose as the carbon source. A decrease in the average diameter of the nanoparticles from 12 to 8 nm results in increased surface area and ofers a perfect match between ions of binary mixture of imidazolium-based fuorinated ionic liquids and the pores of carbon. Short-range graphene layers produced with 8-nm silica nanoparticles lead to the creation of transport channels which better accommodate ions. We explain these fndings per coulombic interactions among the ions and between the pore wall and the ionic species under confnement and electrochemical polarization conditions. Further, it is shown that a microporous carbon (another in-house produced rice-husk carbon SBET=1800 m2 ∙g−1) performs better than hierarchical carbons at room temperature; however, thanks to the large fraction of mesopores, the latter exhibit far higher capacitance down to−40 °C. While the ordering of ions in confnement is more critical at room temperature and dictated by the micropores, low temperature performance of supercapacitors is determined by the mesopores that provide channels for facile ion movement and keep the bulk ionic liquid–like properties

Efficient Polysulfides Conversion Kinetics Enabled by Ni@CNF Interlayer for Lithium Sulfur Batteries

Recent advances in the development of lithium-sulfur batteries (Li-S) demonstrated their high effectiveness owing to their tremendous theoretical specific capacity and high theoretical gravimetrical energy. Nevertheless, the potential commercialization of Li-S is significantly held by the insulating nature of sulfur and complicated RedOx reactions during the electrochemical charge-discharge processes. This paper presents nickel nanoparticles embedded carbon nanofibers interlayer (Ni@CNF) between a cathode and a separator as an additional physical barrier against lithium polysulfides shuttle for their efficient conversion during the charge-discharge cycling. Furthermore, the interlayer provides an auxiliary electron pathway with subsequent lowering of the charge transfer resistance. The electrochemical analysis of a Li-S cell with the Ni@CNF interlayer demonstrated high initial discharge capacities of 1441.2 mAh g-1 and 1194.2 mAh g-1 at 0.1 and 1.0 C rates, respectively, with remarkable capacity retention of ~83% after 100 cycles. This study revealed the advantageous impact of Ni@CNF towards solving the major issues of lithium-sulfur batteries, i.e., sluggish kinetics and the shuttle effect

CVD graphene growth on a surface of liquid gallium

Abstract This paper presents the results of the experiments on graphene growth on the surface of a liquid metal gallium that appeared to have the catalytic ability in respect to carbon atoms. Due to the absence of crystal lattice, the liquid catalyst does not influence the graphene formation and as a result, the latter has uniform hexagonal structure. The work comprises the data on graphene synthesis on the surface of pure gallium with different precursors and on the surface of pre-treated gallium without any precursor. Obtained materials were characterized by RAMAN, TEM, SEM and FT-IR techniques