N-doped porous carbon film electrodes for electrochemical capacitor, made by electrospray of sol precursors

Revisiting the Effect of Pyrolysis Temperature and Type of Activation on the Performance of Carbon Electrodes in an Electrochemical Capacitor

“…For example, the oxygen functional groups (C-O, and C=O) present on the outer surface or at the edge of the basal plane are responsible for acidic characteristics [ 6 , 30 ], which improved the hydrophilicity and rapid charge transport in the electrode. On the other hand, the basicity of basic oxygen functionalities or resonating electrons of the aromatic ring in carbon leads to a redox reaction from the faradic interaction with electrolyte ions [ 2 , 3 ]. Therefore, the relative contributions of the porous structure arising from the micro-mesopores, the amount of total, and the surface oxygen with the type of functionalities, electrical conductivity, wettability, and the resulting redox activity will vary with the carbonisation temperature and, in turn, influence the final performance of the carbon electrodes.…”

“… where C s is the specific capacitance of a single electrode (F g −1 ), I is the current (A), ΔV is the applied potential window (V), m is the mass of active material of the single CX electrode (g), S is the scan rate (V s −1 ), t d is the discharging time (s), and IR is the ohmic drop (V). The Coulombic efficiency ), specific energy (E in Wh kg −1 ), and specific power (P in W kg −1 ) of the electrochemical cell were estimated using Equations (7)–(9), respectively [ 2 , 6 ]. where t c is the charging time (s), and C is the capacitance of the symmetric cell (F g −1 ).…”

“…In recent years, research on the development of carbon-based electrodes for ECs has focused on improving their surface area with a proper pore hierarchy and incorporating heteroatoms or functionalities into the carbon structure [ 2 , 3 , 4 , 5 , 6 ]. As most of the surface area for double-layer charge storage is held inside micropores (<2 nm pore size), the pore hierarchy or connectivity between meso-micropores plays a vital role in the rapid transport of electrolyte ions to the internal surface [ 7 ].…”

“…The introduction of surface functionality using heteroatoms (e.g., N, S, P, O, B) is another way to enhance charge storage in carbon electrodes [ 8 , 9 ]. Such functionalities contribute to increase surface polarity, wettability, electric conductivity, and electron donor/acceptor properties, and also act as active sites for pseudocapacitance [ 2 ]. The incorporation of these functionalities into carbon through the precursor itself offers feasibility with a uniform distribution of functionalities over the carbon network and an improvement in bulk properties compared to other post-treatments used for functionalisation [ 6 ].…”

“…Furthermore, the particle size of the organic gel has found an intense effect on the surface area, which increases for the carbonisation temperature from 750 to 900 °C for an average particle size (dp) <212 µm [ 19 ]. In addition, a carbonaceous product emerges with different oxygen functionalities that significantly alter acidic-basic characteristics and surface interactions, which are responsible for the adsorption or improved wettability of electrolyte ions [ 2 , 3 , 6 , 22 ]. On the other hand, too many bulky oxygen groups can damage the sp 2 carbon network and decrease electrical conductivity, ultimately hindering the charge transport in carbon electrodes [ 23 , 24 ].…”