The Impedance Response of a Porous Electrode Composed of Intercalation Particles

Abstract

A mathematical model is developed to describe the impedance response of a porous electrode composed of spherical intercalation particles. The model considers a porous electrode without solution-phase diffusion limitations. The model is developed by first deriving the impedance response of a single intercalation particle, obtained by solving a set of governing equations which describe charge-transfer and double-layer charging at the surface, solid-phase diffusion inside the particle, and an open-circuit potential which varies as a function of intercalant concentration. The model also considers the effect of an insulating film surrounding the particle. The governing equations are linearized to take advantage of the small amplitude of the perturbing current in impedance analysis. Once the impedance of a single particle is determined, this result is incorporated into a model which describes a porous electrode limited by ohmic drop in the solution and solid phases, and by the impedance of the particles of which the porous electrode is composed. The model can be used to examine the effect of physical properties and particle-size distributions in the porous electrode, and the usefulness of impedance analysis to measure solid-phase diffusion coefficients is scrutinized.

Advanced nanostructured carbon materials for electrical double layer capacitors

“…Average pore wall thickness δ w for different nanostructured carbon materials studied. For the detailed analysis of adsorption processes (charge accumulation, mass transfer) of ions at nanoporous carbon electrodes the various model approximations have been tested including classical Frumkin-Melik-Gaikazyan [28], Randles [29], Paasch et al [30] and Meyer et al [31] models.…”

“…The obtained value of resistivity of the electrode material per unit length ρ 1 is independent of the electrolyte concentration studied [6]. It should be noted that the simplified Meyer et al model [31] where the intercalation of ions into the nanoporous carbon material has not been taken into account can be used for the fitting of the impedance data for nanoporous carbon | non-aqueous electrolyte systems with very good fitting parameters. …”

Germanium coating boosts lithium uptake in Si nanotube battery anodes

“…Diffusion of ions gives rise to distinctive impedance patterns characterized by Warburglike responses as ). Previous models based on spatially-restricted ion diffusion were proposed relying on a distribution of diffusion lengths [21], or electronic transport limitations [22]. However, Si NT and Si/Ge DLNT electrodes function by alloying reactions yielding a complete chemical and structural electrode material rearrangement.…”

“…Among various alloying-type anode materials for lithium ion batteries (LIB), Si has received considerable attention due to its highest theoretical capacity, 4200 mAh/g at the fully lithiated state Li 22 Si 5 , being the most promising alternative for carbon anodes [1,2]. Although the fast capacity fading of Si electrode (resulting from large volume change associated with lithium ion) has been considered as a main obstacle for its practical use, significant improvement in the cycle performance has been achieved by engineering the geometry and dimension of Si anode materials [3,4].…”

Influence of Microstructure on Impedance Response in Intercalation Electrodes

“…[10][11][12][13][14][15][16][17] By investigating the impedance response, the charge transport resistance, including electron transport in the solid phase, ionic transport in the electrolyte, solid-state diffusion in the active material, and the intercalation process, can be quantified.…”