Sub-micrometer Novolac-Derived Carbon Beads for High Performance Supercapacitors and Redox Electrolyte Energy Storage

Abstract

Carbon beads with sub-micrometer diameter were produced with a self-emulsifying novolac-ethanol-water system. A physical activation with CO2 was carried out to create a high microporosity with a specific surface area varying from 771 (DFT) to 2237 m(2)/g (DFT) and a total pore volume from 0.28 to 1.71 cm(3)/g. The carbon particles conserve their spherical shape after the thermal treatments. The controllable porosity of the carbon spheres is attractive for the application in electrochemical double layer capacitors. The electrochemical characterization was carried out in aqueous 1 M Na2SO4 (127 F/g) and organic 1 M tetraethylammonium tetrafluoroborate in propylene carbonate (123 F/g). Furthermore, an aqueous redox electrolyte (6 M KI) was tested with the highly porous carbon and a specific energy of 33 W·h/kg (equivalent to 493 F/g) was obtained. In addition to a high specific capacitance, the carbon beads also provide an excellent rate performance at high current and potential in all tested electrolytes, which leads to a high specific power (>11 kW/kg) with an electrode thickness of ca. 200 μm.

Niobium carbide nanofibers as a versatile precursor for high power supercapacitor and high energy battery electrodes

“…This is sought to be achieved by the development of hybrid technologies, such as lithium ion capacitors, 7 and employment of rapid pseudocapacitive materials 8 or redox-active electrolytes. 9,10 A particularly attractive group of electrode materials are binder-free and free standing ber mats. 11,12 The open-mesh percolated network and the possibility of creating a continuous active material are highly attractive to achieve an improved power performance.…”

Controlled Air‐Etching Synthesis of Porous‐Carbon Nanotube Aerogels with Ultrafast Charging at 1000 A g−1

“…The optimized geometry of the 1D nanotube shows ordered pores, and the calculated band structure and DOS exhibit metallic features as characterized by the high DOS and the bands crossing the Fermi level in the high symmetry k point path of Γ (0, 0, 0) → Z (0, 0, 0.5) (Figure S8, Supporting Information). In comparison, previously reported porous carbon materials are mainly in the form of particles with various shapes such as spheres, nanosheets, hollow cages, and other irregular particles …”

“…In comparison, previously reported porous carbon materials are mainly in the form of particles with various shapes such as spheres, nanosheets, hollow cages, and other irregular particles. [6,31,40,41] The energy/power densities are important criteria for supercapacitors. The Ragone plot shows that our PCN electrodes possess an outstanding power density of 265.6 kW kg −1 at an energy density of 1. at a power density of 500 W kg −1 (Figure 5a).…”

N‐Doped Hierarchical Porous Carbon with Open‐Ended Structure for High‐Performance Supercapacitors

“…EDLCs have been widely utilized in portable electronic devices due to their distinctive electrical properties. In general, EDLCs prefer to employ carbon materials with high surface area, porosity and high electrical conductivity as electrode materials, such as activated carbons,, carbon aerogel, carbon nanosheets,, carbon nanotubes, carbon spheres,, hollow carbon spheres, carbon network, and carbon nanofibers …”