Electrochemical Cell and Thermodynamics

Combined Computational and Experimental Study on the Influence of Surface Chemistry of Carbon-Based Electrodes on Electrode–Electrolyte Interactions in Supercapacitors

“…Supercapacitors represent a promising technique between batteries and capacitors and combine the advantages of both technologies. − They have excellent charging characteristics of conventional capacitors, but offer considerably higher capacitances through a combination of double-layer capacitor and pseudocapacitor. , The great advantage of supercapacitors over batteries is the high power density, which ensures remarkably faster charging and discharging. ,, At the same time, supercapacitors tolerate significantly more recharging cycles compared to conventional batteries and thus provide a long lifetime without any need for replacement. , Moreover, the operating temperature of supercapacitors covers a much broader range and they can be designed environmentally friendly. − Supercapacitors are capable of shielding devices from voltage fluctuations and are used in various areas ranging from renewable energy over large-scale backup power up to automotive applications, e.g., for recapturing braking energy …”

“…Despite many benefits, supercapacitors offer only a low energy density, are limited to low cell voltages, and suffer from high self-discharging. 7 For overcoming the limitations and improving the performance of theses capacitors, it is essential to understand processes at the molecular level. Although much work has been dedicated to broaden the understanding of the energy-storage mechanism of these systems, see, e.g., refs 3, 15−21 and references therein, there are ongoing efforts to explore the relevant processes and to elucidate the complex interplay of parameters such as pore confinement, wettability, mobility, or variations in the local composition that govern the performance of the capacitors.…”

“…1,5,6 At the same time, supercapacitors tolerate significantly more recharging cycles compared to conventional batteries and thus provide a long lifetime without any need for replacement. 7,8 Moreover, the operating temperature of supercapacitors covers a much broader range and they can be designed environmentally friendly. 7−9 Supercapacitors are capable of shielding devices from voltage fluctuations and are used in various areas ranging from renewable energy over large-scale backup power up to automotive applications, e.g., for recapturing braking energy.…”

“…Commercially, organic electrolytes containing tetraethylammonium (TEA) tetrafluoroborate (BF 4 ) salts are used, which allow operating voltages up to 2.7 V. − High capacitances can be achieved using porous carbon electrodes, which possess a large surface area. ,, When an electric field is applied, the ions in the electrolyte diffuse into the pores and charge accumulates at the electrode–electrolyte interface. Despite many benefits, supercapacitors offer only a low energy density, are limited to low cell voltages, and suffer from high self-discharging . For overcoming the limitations and improving the performance of theses capacitors, it is essential to understand processes at the molecular level.…”