Experimental Characterization of Lithium-Ion Cell Strain Using Laser Sensors

Abstract

The characterization of thickness change during operation of LFP/Graphite prismatic batteries is presented in this work. In this regard, current rate dependence, hysteresis behaviour between charge and discharge and correlation with phase changes are deepened. Experimental tests are carried out with a battery testing equipment correlated with optical laser sensors to evaluate swelling. Furthermore, thickness change is computed analytically with a mathematical model based on lattice parameters of the crystal structures of active materials. The results of the model are validated with experimental data. Thickness change is able to capture variations of the internal structure of the battery, referred to as phase change, characteristic of a certain state of charge. Furthermore, phase change shift is a characteristic of battery ageing. Being able to capture these properties with sensors mounted on the external surface the cell is a key feature for improving state of charge and state of health estimation in battery management system.

Chemical lattice strain in nonstoichiometric oxides: an overview

“…The fact that chemical strain can lead to mechanical failure is particularly well known in the field of solid-state battery development, since many widely employed Li-ion conducting materials experience large chemical expansion—up to several percents—upon lithiation/delithiation. 47,49,60,265,267–269 This is also superimposed on the complex phase behavior of Li-conductors depending on lithium concentration, 60,265,267,268,270 formation of dendrites, 47,49,271 etc. Therefore, to minimize the unwanted chemical stress effects, the components and microstructure of solid-state batteries need to be optimized with respect to chemical expansion.…”

Quantifying Volume Change in Porous Electrodes via the Multi-Species, Multi-Reaction Model

“…Probing further into the graphite OCV behavior, 75,76 we propose the following alignment between the MSMR model galleries and the lithium stages as seen in Fig. 6.…”

Methods for Quantifying Expansion in Lithium-Ion Battery Cells Resulting from Cycling: A Review

“…Stage 2L only appears during delithiation (discharge) and stage 3 appears during lithiation (charge) and forms directly into stage 2 [25]. During deintercalation, the lithium ions are extracted randomly out of the structure, which forms a solid solution or a liquid, rather than a sorted phase [26]. The transition from stage 4 to stage 3 requires one out of six layers to be opened, the transition from stage 3 to stage 2 requires two out of six layers to be opened, and the transition from stage 2 to stage 1 requires three out of six layers to be opened.…”