Transmission Line Model Impedance Analysis of Lithium Sulfur Batteries: Influence of Lithium Sulfide Deposit Formed During Discharge and Self-Discharge

Abstract The effect of Li2S deposition on the impedance response of Li-S battery cells is investigated using a simplified cell design, systematic impedance spectroscopy measurements combined with transmission line modeling, and a complementary microscopy analysis. Glassy carbon cathodes are employed to build and validate the proposed transmission line model, which is later on employed to investigate the effect of various parameters of Li2S deposit (coverage, thickness, porosity) on cell’s impedance. Among others, the model is applied to study the effect of discharge and self-discharge. Finally, the simplified planar cathode is exchanged with a more conventional mesoporous carbon cathode to determine the effect of Li2S deposition on the impedance of a commercially viable cell design. We have found that Li2S deposit has little effect on the impedance response, owing to its porous structure. The most noticeable change stemming from the process of Li2S deposition is due to the depletion of polysulfide species concentration in the electrolyte, which decreases the chemical capacitance and increases the tail height in the low frequency region of the impedance spectra.

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Impedance analysis on electric double layer capacitor with transmission line model

Journal of Power Sources ◽

10.1016/j.jpowsour.2006.09.077 ◽

2007 ◽

Vol 164 (1) ◽

pp. 415-424 ◽

Cited By ~ 90

Author(s):

Masayuki Itagaki ◽

Satoshi Suzuki ◽

Isao Shitanda ◽

Kunihiro Watanabe ◽

Hiroshi Nakazawa

Keyword(s):

Transmission Line ◽

Double Layer ◽

Electric Double Layer ◽

Impedance Analysis ◽

Electric Double Layer Capacitor ◽

Transmission Line Model ◽

Line Model ◽

Double Layer Capacitor

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H 2-Optimal Low Order Transmission Line Models

ASME/BATH 2019 Symposium on Fluid Power and Motion Control ◽

10.1115/fpmc2019-1688 ◽

2019 ◽

Cited By ~ 1

Author(s):

Bernhard Manhartsgruber

Keyword(s):

Power Systems ◽

Transmission Line ◽

Code Generation ◽

Transfer Functions ◽

Linear Time ◽

State Space Model ◽

Low Frequency ◽

Transmission Line Model ◽

Line Model ◽

Low Order

Abstract Transmission line modeling has played a crucial role in understanding the dynamics of fluid power systems. A vast body of literature exists from simple lumped parameter approaches to fully coupled three-dimensional fluid structure interaction models. When it comes to computationally efficient, yet physically sound low order models needed for fast computations iteratively called by optimization codes or for the purpose of model based control design, there is still room for improvement. Modal approximations of the input-output behaviour of liquid transmission lines have been around for decades. The basic idea of tuning the parameters of a canonical linear time invariant state space model to fit the transfer functions of a transmission line model in the H2-optimal sense under passivity constraints has been published by the author of the present paper in the past. However, the method so far was barely usable due to numerical difficulties in the underlying optimization process. A new implementation of the method employing quadruple-precision floating point numbers has recently been found to resolve the convergence problems and is reported in the present paper. The new version of the method is based on analytic computation of the cost and constraint functions as well as their gradients in the computer algebra package Maple and automatic code generation for compilation in FORTRAN. Results are very promising because both the entire low frequency behaviour and the first three eigenmodes of a transmission line model can be accurately covered by a model of order eight only.

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