Phase Transformation and Microstructural Evolution of CuS Electrodes in Solid‐State Batteries Probed by In Situ 3D X‐Ray Tomography. Issue 2 (28th November 2022)

• Record Type: Journal Article
• Authors: Zhang, Zhenggang; Dong, Kang; Mazzio, Katherine A.; Hilger, André; Markötter, Henning; Wilde, Fabian; Heinemann, Tobias; Manke, Ingo; Adelhelm, Philipp
• Is Part Of: Advanced energy materials. Volume 13:Issue 2(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-11-28
• Subjects: copper sulfide -- crack evolution -- digital volume correlation -- phase transformation -- solid‐state batteries -- stack pressure evolution -- X‐ray tomography; Energy harvesting -- Materials -- Periodicals; Energy conversion -- Materials -- Periodicals; Energy storage -- Materials -- Periodicals; Photovoltaics -- Periodicals; Fuel cells -- Periodicals; Thermoelectric materials -- Periodicals; 621.31
• DOI: 10.1002/aenm.202203143
• Languages: English
• ISSNs: 1614-6832

Abstract

Abstract: Copper sulfide shows some unique physico‐chemical properties that make it appealing as a cathode active material (CAM) for solid‐state batteries (SSBs). The most peculiar feature of the electrode reaction is the reversible formation of µm‐sized Cu crystals during cycling, despite its large theoretical volume change (75%). Here, the dynamic microstructural evolution of CuS cathodes in SSBs is studied using in situ synchrotron X‐ray tomography. The formation of µm‐sized Cu within the CAM particles can be clearly followed. This process is accompanied by crack formation that can be prevented by increasing the stack pressure from 26 to 40 MPa. Both the Cu inclusions and cracks show a preferential orientation perpendicular to the cell stack pressure, which can be a result of a z‐oriented expansion of the CAM particles during lithiation. In addition, cycling leads to a z‐oriented reversible displacement of the cathode pellet, which is linked to the plating/stripping of the Li counter electrode. The pronounced structural changes cause pressure changes of up to 6 MPa within the cell, as determined by operando stack pressure measurements. Reasons for the reversibility of the electrode reaction are discussed and are attributed to the favorable combination of soft materials. Abstract : Using in situ X‐ray tomography, the phase transformation and microstructural evolution of a copper sulfide cathode in solid‐state batteries is 3D visualized and characterized. Copper inclusions generate after phase transformation and the electrode cracks have a strong preferential orientation within the x‐y plane of the cell. The particle expansion‐induced electrode displacement is more pronounced along z ‐axis perpendicular to the cathode pellet.