耐デンドライト性固体電解質の探求における光弾性の活用(Utilizing Photoelasticity in the Quest for Dendrite-Resistant Solid Electrolytes)

2023-11-15

2023-11-09 ジョージア工科大学

◆ジョージア工科大学、ブラウン大学、南洋工科大学、MITの研究者が、初めて固体電池の電解質周りで発生する応力を文書化しました。デンドライトと呼ばれる金属の微細な突起周りに応力が蓄積し、これが固体電解質電池をショートさせる原因とされてきましたが、その応力を正確に測定する手段がなかった。
◆研究者たちは、光弾性法を使用してデンドライト周りで生じる機械的な応力を初めて測定し、固体電池の効率向上に寄与する可能性があります。

＜関連情報＞

光弾性を用いたセラミック電解質中のデンドライト誘起応力のオペランド測定 Operando measurements of dendrite-induced stresses in ceramic electrolytes using photoelasticity

Christos E. Athanasiou, Cole D. Fincher, Colin Gilgenbach, Huajian Gao, W. Craig Carter, Yet-Ming Chiang, Brian W. Sheldon
Matter Published: November 7, 2023
DOI:https://doi.org/10.1016/j.matt.2023.10.014

Progress and potential

Chemo-mechanical phenomena impact the cyclability of solid-state batteries. While conventional Li-ion cells require constant ionic contact between active components, the rigid nature of solid-solid interfaces presents new challenges for maintaining mechanical contact. The loss of mechanical contact at interfaces leads to cell failure. Both cathodes and anodes undergo stress during cycling, potentially fracturing the solid electrolyte. In addition, dendrite growth induces stresses within the electrolyte, affecting degradation and cell lifespan. Despite their importance, no direct stress measurements inside solid electrolytes during cycling have been made due to experimental challenges. To overcome this, a photoelasticity-based platform was created, allowing stress analysis near chemo-mechanical events and aiding in studying battery material failures at varied scales.

Summary

Fundamental understanding of stress buildup in solid-state batteries is elusive due to the challenges in observing electro-chemo-mechanical phenomena inside solid electrolytes. In this work, we address this problem by developing a method to directly measure stresses within solid-state electrolytes. As a proof-of-concept, we provide the first direct measurements of the stress fields generated around the lithium metal dendrites in a model garnet electrolyte, Li_6.75La₃Zr_1.75Ta_0.25O₁₂, and show that these are consistent with the predictions for an internally loaded crack in an elastic solid. The measurements are based on employing the principle of photoelasticity to probe the stress fields during operando electrochemical cycling in a plan-view cell. This new experimental methodology provides a means to access chemo-mechanical events in solid-state batteries and has the potential to provide insight into a variety of chemo-mechanical failure modes.