Future Directions for Electrochemical Capacitors

Abstract

Recently, extensive research efforts on electrochemical energy storage materials have been developed, motivated by the urgent need for efficient energy storage devices for the automotive market. Electrochemical capacitors (ECs) bridge the gap between batteries and solid-state and electrolytic capacitors. While the high power density of these devices is attractive, greater energy density is required for the future. To address this need, both experimental approaches that modify the electrolyte–electrode interface and the use of analytical methods to characterize these interfaces are being actively pursued. The development of advanced in situ analytical techniques to understand fundamental electrochemical processes and structural effects (pores, surface groups) down to the nanoscale level is expected to play a key role in developing the next generation of ECs with high energy and high power performance.

Optimized Lithography-Free Fabrication of Sub-100 nm Nb2O5 Nanotube Films as Negative Supercapacitor Electrodes: Tuned Oxygen Vacancies and Cationic Intercalation

“…A plethora of merits qualified supercapacitors (SCs) as leading candidates for high-performance next-generation energy storage devices. − While the energy density of SCs is relatively lower than that of battery devices, asymmetric SC (A-SC) and hybrid SC (H-SC) configurations were purposed to bridge such an energy density gap. − However, there are many debates in the literature concerning the definition of A-SCs and H-SCs. , The A-SC is a device with either two electrodes made of the same material and different mass loadings or two electrodes made of different materials, namely, capacitive and pseudocapacitive, based on their way to store ions/charges. , In contrast, the H-SC is the term used when the device contains one battery-like electrode material. , To this end, the studies targeting high-performance A-SCs and H-SCs are mainly focused on the improvement of the anode materials, with little attention devoted to developing negative electrode materials. − The inefficient performance of either the positive or negative electrode will restrict the full tapped capacitance of the device, limiting the overall device performance. − Noteworthily, more efforts should be directed toward the synthesis and development of functional negative electrode materials. , …”

How chemical defects influence the charging of nanoporous carbon supercapacitors

“…The current CDCL method allows exploration of how doping with elements such as N, S, etc., influences ion adsorption and in-pore docking ( 53 ). Furthermore, the current CDCL method could be coupled with a CV approach in order to take into account the variation of the substrate defects charge upon ionic thermal movement.…”

“…At voltage set back to zero, about 10% of the formerly docked Na + ions (about 3% of the total number of cations) and 30% of the adsorbed Cl − (about 10% of the total number of anions) are still trapped inside the electrodes (after 1 ns of unloading, 2 Na + and 6 Cl − are inside the electrodes, see S.I.). Note that desorption, which is and the in-pore docking (54). Furthermore, the current CDCL 399 method could be coupled with a constant voltage approach in order to take into account the variation of the substrate defects charge upon ionic thermal movement.…”

High performance supercapacitors based on wood-derived thick carbon electrodes synthesized via green activation process

“…Supercapacitors have garnered considerable research interest as a power supply to complement or even replace batteries due to their low cost, fast charging/discharging rate, high safety, and good durability. 1,2 Electrical double-layer capacitors (EDLCs), which store energy by the electrostatic adsorption/ desorption of electrolyte ions into nanopores of porous carbon electrodes, are of particular interest. [3][4][5] The motivation to develop EDLCs with high energy/power density has spurred their practical applications.…”