Implementation and Preliminary Assessment of a Segmented Platform for Spatially Resolved Electrochemical Studies of Sulfurized Polyacrylonitrile Cathodes in Lithium-Sulfur Pouch Cells

Kurzfassung

Lithium-Sulfur (Li-S) batteries represent a promising next-generation energy storage technology, with recent advancements bringing commercial prototypes closer to deployment. However, as the technology is scaled, their widespread practical adoption remains hindered by intricate electrochemical processes and the development of spatial inhomogeneities across the sulfur cathode, among other persistent challenges. Understanding these localised phenomena in large-format cells is critical, as non-uniformities in reaction distribution, degradation, and species transport can significantly limit performance and lifespan. To date, capturing such operando measurements with high spatial resolution remains a general and significant challenge in battery diagnostics.

This study presents a Li-S pouch cell architecture incorporating a custom-designed segmented cathode current collector. Functioning as an integrated sensing interface, the addressable segment array enables spatially resolved measurements across the cathode surface under operando conditions. A continuous layer of Sulfurized Polyacrylonitrile (SPAN) cathode material was wet coated onto the segmented contact matrix, facilitating locally resolved current and impedance measurements at multiple discrete positions.

Multiple segmented Li-S pouch cells were fabricated and tested under galvanostatic cycling conditions to validate the integrated measurement platform. Periodically throughout cycling, potentiostatic impedance measurements were acquired across the current-collecting segments at open-circuit and charge/discharge cut-off states. Segmented measurements revealed persistent spatial heterogeneity in current distribution and impedance, despite homogeneous behaviour inferred from conventional full-cell measurements.

By enabling spatially resolved diagnostics, this approach offers new insights into degradation mechanisms in Li-S batteries, and establishes a powerful platform for validating strategies to enhance electrode uniformity and cell longevity.