Developments in X-ray tomography characterization for electrochemical devices

Abstract

Over the last century, X-ray imaging instruments and their accompanying tomographic reconstruction algorithms have developed considerably. With improved tomogram quality and resolution, voxel sizes down to tens of nanometres can now be achieved. Moreover, recent advancements in readily accessible lab-based X-ray computed tomography (X-ray CT) instruments have produced spatial resolutions comparable to specialist synchrotron facilities. Electrochemical energy conversion devices, such as fuel cells and batteries, have inherently complex electrode microstructures to achieve competitive power delivery for consideration as replacements for conventional sources. With resolution capabilities spanning tens of microns to tens of nanometres, X-ray CT has become widely employed in the three-dimensional (3D) characterisation of electrochemical materials. The ability to perform multiscale imaging has enabled characterisation from system-down to particle-level, with the ability to resolve critical features within device microstructures. X-ray characterisation presents a favourable alternative to other 3D methods such as focused ion beam scanning electron microscopy, due to its non-destructive nature, which allows four-dimensional (4D) studies, three spatial dimensions plus time, linking structural dynamics to device performance and lifetime. X-ray CT has accelerated research from fundamental understanding of the links between cell structure and performance, to the improvement in manufacturing and scale-up of full electrochemical cells. Furthermore, this has aided in the mitigation of degradation and celllevel failures such as thermal runaway. This review presents recent developments in the use of X-ray CT as a characterisation method and its role in the advancement of electrochemical materials engineering.

Real-time multi-length scale chemical tomography of fixed bed reactors during the oxidative coupling of methane reaction

“…Over the past decade, the numerous developments of in situ and operando characterisation techniques have provided the scientific community new tools that can be employed to advance our understanding of the complex structure-activity relationships in real working catalysts and functional materials [35][36][37][38][39][40][41][42][43][44][45] . More importantly, the spatially-resolved spectroscopic/scattering signals collected with the tomographic approach allow us to investigate the interior of an intact device, reactor or catalyst in its industrial form and under relevant operating conditions .…”

Use of X-ray computed tomography for understanding localised, along-the-channel degradation of polymer electrolyte fuel cells

“…To better understand the internal workings and structural changes occurring during degradation testing, an increasing body of work is being reported on the design and operation of miniaturised PEFCs for use in in-situ and operando studies using X-ray computed tomography (X-ray CT), as discussed in the reviews of Meyer et al [14] and Heenan et al [15]. Such studies are carried out either on synchrotron beamlines at national facilities [16][17][18] or in laboratory-based X-ray CT instruments [19].…”

Machine-learning-revealed statistics of the particle-carbon/binder detachment in lithium-ion battery cathodes

“…Microstructural characterization of the composite electrode with desired representativeness, precision, reliability, and efficiency, however, is nontrivial. X-ray tomography 3,4 has been widely adopted to conduct threedimension (3D) tomographic imaging of the composite electrode in a number of different experimental modalities. For example, Xray micro-and nano-tomography has been utilized to follow the dynamic evolution of the electrode materials under operating conditions at the electrode level [5][6][7][8][9] and at the particle scale [10][11][12][13] .…”