Quantifying Bulk Electrode Strain and Material Displacement within Lithium Batteries via High‐Speed Operando Tomography and Digital Volume Correlation

Abstract

Tracking the dynamic morphology of active materials during operation of lithium batteries is essential for identifying causes of performance loss. Digital volume correlation (DVC) is applied to high‐speed operando synchrotron X‐ray computed tomography of a commercial Li/MnO2 primary battery during discharge. Real‐time electrode material displacement is captured in 3D allowing degradation mechanisms such as delamination of the electrode from the current collector and electrode crack formation to be identified. Continuum DVC of consecutive images during discharge is used to quantify local displacements and strains in 3D throughout discharge, facilitating tracking of the progression of swelling due to lithiation within the electrode material in a commercial, spiral‐wound battery during normal operation. Displacement of the rigid current collector and cell materials contribute to severe electrode detachment and crack formation during discharge, which is monitored by a separate DVC approach. Use of time‐lapse X‐ray computed tomography coupled with DVC is thus demonstrated as an effective diagnostic technique to identify causes of performance loss within commercial lithium batteries; this novel approach is expected to guide the development of more effective commercial cell designs.

Digital Volume Correlation: Review of Progress and Challenges

“…However, surprisingly, very few published studies made use of DVC to translate microstructure changes into 4D displacement (or velocity) fields. One exception though is due to one team that studied lithium batteries in operando [178,65]. In these examples, DVC could inform on the strains, and hence ageing conditions under electrochemical changes, and finally provided a clear picture of the performance loss of such batteries.…”

Characterising the structural properties of polymer separators for lithium-ion batteries in 3D using phase contrast X-ray microscopy

“…The ceramic layers are shown to have little effect on the overall tortuosity of the membrane, but have been shown to improve the thermal and mechanical properties [52,53], as well as the wettability of polymer separators [54,55]. Hence, the combination of high tensile strength resulting from its isotropic structure, high tortuosity, and the presence of the ceramic layer [52,53] would help mitigate the risks associated overheating, dendrite growth and electrode displacement [56,57], making this separator favourable for safety critical applications.…”

4D imaging of lithium-batteries using correlative neutron and X-ray tomography with a virtual unrolling technique

“…The non-destructive nature of both X-ray and neutron CT provides opportunities for four-dimensional (4D) studies, that is, the ability to explore the evolution of three-dimensional (3D) structures with time [22][23][24] . The authors have previously used highspeed X-ray CT to produce consecutive datasets of batteries during discharge for quantitative displacement measurements via digital volume correlation (DVC) 25 . The DVC of consecutive tomograms was used to explore the evolution of electrode structures in Li primary cells, which are widely used across consumer electronics, backup-power and aerospace applications.…”