(Invited) Interfaces and Bulk: The Challenge of Heterogeneities in Solid Electrolytes

Solid electrolyte failure, its onset, and growth is largely discussed in terms of interfacial challenges. Heterogeneities at the interface lead to cascading issues that accelerate failure in solid electrolytes. However, similar observations are fewer and harder to obtain for the bulk of solid electrolyte materials. Herein, we discuss heterogeneities as they play a role at multiple length-scales : from the nanoscale local contacts of electrode | electrolyte, to more microscale roughness of the physical entities involved and at the bulk scale. We use atomic force microscopy, a custom built spatial electrochemical setup, and advanced characterization tools (synchrotron X-ray based) to investigate these heterogeneities. We will showcase that heterogeneities are indeed crucial in dictating the electrochemical performances of the solid electrolytes for a range of different material systems. We will conclude with a discussion of pathways that can help ameliorate these heterogenieties for high performance solid-state battery systems. References: Dixit, M. B., Vishugopi, B. S., Zaman, W., Kenesei, P., Park, J. S., Almer, J., Mukherjee, P. P., & Hatzell, K. B. (2022). Polymorphism of garnet solid electrolytes and its implications for grain-level chemo-mechanics. Nature Materials.(2022) 21 , 1298–1305 Dixit, M., Beamer, C., Amin, R., Shipley, J., Eklund, R., Muralidharan, N., Lindqvist, L., Fritz, A., Essehli, R., Balasubramanian, M., & Belharouak, I. (2022). The Role of Isostatic Pressing in Large-Scale Production of Solid-State Batteries. ACS Energy Letters, 2022,11, 3936–3946. Dixit, M., Muralidharan, N., Parejiya, A., Jafta, C., Du, Z., Neumayer, S., Essehli, R., Amin, R., Balasubramanian, M., & Belharouak, I. (2022). ACS Appl. Mater. Interfaces 2022, 14, 39, 44292–44302 Figure 1