Electrochemical Model-Based Investigation of Thick LiFePO4 Electrode Design Parameters

Abstract

The electrification of the powertrain requires enhanced performance of lithium-ion batteries, mainly in terms of energy and power density. They can be improved by optimising the positive electrode, i.e., by changing their size, composition or morphology. Thick electrodes increase the gravimetric energy density but generally have an inefficient performance. This work presents a 2D modelling approach for better understanding the design parameters of a thick LiFePO4 electrode based on the P2D model and discusses it with common literature values. With a superior macrostructure providing a vertical transport channel for lithium ions, a simple approach could be developed to find the best electrode structure in terms of macro- and microstructure for currents up to 4C. The thicker the electrode, the more important are the direct and valid transport paths within the entire porous electrode structure. On a smaller scale, particle size, binder content, porosity and tortuosity were identified as very impactful parameters, and they can all be attributed to the microstructure. Both in modelling and electrode optimisation of lithium-ion batteries, knowledge of the real microstructure is essential as the cross-validation of a cellular and lamellar freeze-casted electrode has shown. A procedure was presented that uses the parametric study when few model parameters are known.

Analysis of Electrochemical Impedance Spectroscopy on Zinc-Air Batteries Using the Distribution of Relaxation Times

“…Figures 6 and A4). The ambient temperature in general has a complex influence on the entire system, i.e., on all transport processes, on reaction kinetics, on reaction potentials and overpotentials and on the material properties [78]. The electrolyte contributes most to the decreasing potential as the temperature decreases [70], e.g., conductivity decreases approximately linearly with decreasing temperatures [79].…”

Are solid-state batteries safer than lithium-ion batteries?

“…The range of LE VF was chosen based on values from experimental work. 41,42 The volume of LE used in this study is only enough to fill the pores of the separator and electrodes. Experimental volumes of LE are typically much higher, potentially leading to greater heat release.…”

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“…The upper and lower bounds for the identifiable parameters were obtained from the literature. [39,42,43] Benchmarking these values is crucial to improve the accuracy of the identification process.…”