Spectral X-ray micro-CT Imaging of Rechargeable Alkaline Batteries

Rechargeable alkaline batteries (RABs) represent a promising post-lithium energy storage technology owing to their intrinsic safety, use of sustainable materials, and compatibility with existing battery manufacturing infrastructure. However, their commercial deployment remains limited by insufficient understanding of ageing and degradation mechanisms. In this work, spectral X-ray micro-computed tomography (S-XµCT) is employed to non-destructively investigate pristine and aged Mn–Bi-based RABs, with the aim of resolving ageing-induced changes. A spectral photon-counting detector was used to acquire multi-energy datasets, which were then processed and decomposed into material-specific volumes corresponding to carbon, manganese, and bismuth. Stability and reproducibility testing confirmed the robustness of the S-XµCT acquisition and decomposition process. Quantitative image analysis revealed a pronounced increase in the number of clustered features in aged samples, strongly localized near the anode interface, with the bismuth specific volume providing improved discrimination compared to the traditional attenuation volume. These results highlight the added value of S-XµCT for material-specific, volumetric assessment of degradation phenomena in rechargeable alkaline batteries and suggests its potential as a non-destructive diagnostic tool for battery ageing studies.