Understanding the Electric Double-Layer Structure, Capacitance, and Charging Dynamics

Abstract

Significant progress has been made in recent years in theoretical modeling of the electric double layer (EDL), a key concept in electrochemistry important for energy storage, electrocatalysis, and multitudes of other technological applications. However, major challenges remain in understanding the microscopic details of the electrochemical interface and charging mechanisms under realistic conditions. This review delves into theoretical methods to describe the equilibrium and dynamic responses of the EDL structure and capacitance for electrochemical systems commonly deployed for capacitive energy storage. Special emphasis is given to recent advances that intend to capture the nonclassical EDL behavior such as oscillatory ion distributions, polarization of nonmetallic electrodes, charge transfer, and various forms of phase transitions in the micropores of electrodes interfacing with an organic electrolyte or ionic liquid. This comprehensive analysis highlights theoretical insights into predictable relationships between materials characteristics and electrochemical performance and offers a perspective on opportunities for further development toward rational design and optimization of electrochemical systems.

Scalable two-tier protruding micro-/nano-optoelectrode arrays with hybrid optical-electrical modalities by hierarchical modular design

“…Compared to the planar electrode with β = 0.97, resembling the ideal capacitor, the micro-/nano-optoelectrode with β = 0.81 shows a nonideal capacitance behavior due to its micro-/nanostructured surface inhomogeneities within the inner Helmholtz plane, where the distribution and dipole moment orientation for water molecules, and surface adsorbed anions/cations can vary significantly at different locations. 47 Lastly, R e for micro-/nano-optoelectrode ( R e ≈ 200 Ω, dev ≈ 0.3 Ω) is larger than the planar electrode ( R e ≈ 90 Ω, dev ≈ 0.4 Ω), which may be associated with the different distances between their working and counter electrodes in the EC-cell.…”

Recent Progresses in Adsorption Mechanism, Architectures, Electrode Materials and Applications for Advanced Electrosorption System: A Review

“…Due to inapplicable conditions of high ion concentration and hydrated ions, some developments to the Gouy–Chapman–Stern double layer model have been made by researchers. In 1947, the Grahame model further refined the Stern layer into the inner Helmholtz plane (IHP) and outer Helmholtz plane (OHP) based on hydration and unhydration of adsorbed ions [ 27 ]. According to the classical double layer theory and the characteristics of ionic liquids, established mean-field theory (MFT) by Kornyshev and co-workers can be used to explain the differential capacitance and double layer structure of the electrolyte/electrode interface.…”

Structural features and electrostatic energy storage of electric double layers in confined polyelectrolyte solutions under low-salt conditions

“…When in contact with an electrolyte solution, a solid wall generally acquires surface charges, which can attract oppositely charged ions (termed counterions) and repel identically charged ions (termed co-ions) in the solution to form a region known as the electric double layer (EDL). [1][2][3][4] The EDL plays a core role in various fields of science and engineering, such as colloid and interface science, 5 electrowetting, 6 electrokinetics, [6][7][8][9][10][11][12] energy conversion and storage, [13][14][15][16][17][18][19][20][21][22] and desalination. 23,24 Therefore, an accurate and reliable description of the EDL is of importance and attracts considerable attention.…”

“…16 Correspondingly, the performances of EDL energy storage in a variety of electrolyte materials (including aqueous electrolytes, organic electrolytes, ionic liquids and solid-state electrolytes) have been extensively investigated for decades. 16,21,63 However, studies on the electrostatic energy storage of the polyelectrolyte EDLs confined by two charged surfaces are still rare, although several pioneering works have shown its promising performance in the field of energy conversion and storage. 37,64 Hence, uncovering the dependence of the electrostatic energy performance of the polyelectrolyte EDLs on various influencing factors is of great importance and in need of further study so as to provide a guide to improving the electrostatic energy storage performance of the polyelectrolyte EDLs.…”