High Energy Density Supercapacitors: An Overview of Efficient Electrode Materials, Electrolytes, Design, and Fabrication

Abstract

Supercapacitors (SCs) are potentially trustworthy energy storage devices, therefore getting huge attention from researchers. However, due to limited capacitance and low energy density, there is still scope for improvement. The race to develop novel methods for enhancing their electrochemical characteristics is still going strong, where the goal of improving their energy density to match that of batteries by increasing their specific capacitance and raising their working voltage while maintaining high power capability and cutting the cost of production. In this light, this paper offers a succinct summary of current developments and fresh insights into the construction of SCs with high energy density which might help new researchers in the field of supercapacitor research. From electrolytes, electrodes, and device modification perspectives, novel applicable methodologies were emphasized and explored. When compared to conventional SCs, the special combination of electrode material/composites and electrolytes along with their fabrication design considerably enhances the electrochemical performance and energy density of the SCs. Emphasis is placed on the dynamic and mechanical variables connected to SCs′ energy storage process. To point the way toward a positive future for the design of high‐energy SCs, the potential and difficulties are finally highlighted. Further, we explore a few important topics for enhancing the energy densities of supercapacitors, as well as some links between major impacting factors. The review also covers the obstacles and prospects in this fascinating subject. This gives a fundamental understanding of supercapacitors as well as a crucial design principle for the next generation of improved supercapacitors being developed for commercial and consumer use.

Between the Electrodes of a Supercapacitor: An Update on Electrolytes

“…2.5 cP for PC results in better conducting electrolytes solutions and lower ESR values. Contrary to an erroneous claim in [28] the dielectric constant of AN (ε r = 36) is not larger than that of PC (ε r = 65), the donor number also relevant for solvation behavior is practically the same for both. Unfortunately AN is a health hazard, its use is limited or prohibited in some countries (e.g.…”

“…The remarkable differences between crystal, Stokes and hydrated radii of a wide selection of ions has been highlighted before [74] . A link between specific capacitance of activated carbon and ionic conductivity claimed in [28] is not at all supported by the quoted references; the problems related to proper data reporting and the insufficient separation of various factors contributing to specific capacitance and energy density addressed elsewhere in the present report [2,70] may have contributed to the erroneous claim. It may also simply be a confusion between correlation, perhaps just coincidental, and a causal relationship.…”

“…Although the focus of research activities related to supercapacitors in research reports, reviews and overviews appears to be focused on active electrode materials, to a lesser extent on auxiliary electrode components like binders, conducting additives and current collectors/electrode supports electrolytes have attracted less interest. Some partial overviews, selective reviews, and collections of such contributions on electrolytes are available [18,28,[54][55][56][57][58][59] . Reports claiming to provide considerations applicable to electrolyte selection are available [60,61] .…”

A Review on the Recent Advances in Battery Development and Energy Storage Technologies

“…EDLCs fnd applications across various sectors, including automotive regenerative braking systems, renewable energy such as smoothing out fuctuations in solar or wind power, consumer electronics like energy backup for smartphones, and industrial applications such as providing burst power for heavy machinery. While EDLCs ofer advantages such as high power density, fast charging/discharging, long cycle life, and reliability, they typically exhibit lower energy density compared to batteries [141]. As a result, they are often used alongside other energy storage technologies to complement their strengths in applications where rapid energy storage and release are critical.…”

Tuning of Ionic Liquid–Solvent Electrolytes for High-Voltage Electrochemical Double Layer Capacitors: A Review

“…Ionic liquids (ILs) are salt-like materials formed by ionic bonds between cations and anions. Due to their wide electrochemical potential windows, high thermal and chemical Typically, the energy density of an EDLC is determined by its electrodes and electrolytes [6]. Based on the equation of energy density (E = 1/2 CV 2 , where C is the capacitance of the electrodes and V represents the operating voltage window) [7], one strategy is to develop novel electrode materials to deliver higher capacitance.…”