Evaluating Interfacial Stability in Solid-State Pouch Cells Via Ultrasonic Imaging

Abstract

Chemical/electrochemical stability at the interfaces greatly affects the performance of solid-state batteries (SSBs). However, the interfacial behavior in SSBs remains elusive due to the subsurface nature of interfaces and the lack of proper characterization methods. Herein, ultrasonic imaging technology is employed to non-destructively investigate the interfacial stability in solid-state pouch cells. Benefiting from the high sensitivity of ultrasound to the gas/vacuum, in-situ ultrasonic imaging can effectively probe the inner gas release and interfacial degradation in pouch cells during long-term cycling. The safety issue of SSBs is highlighted by the flammable gas release detected in ultrasonic images. And the increased interfacial resistance either from contact loss or passivation layer growth is well distinguished. The gradual oxidation and gassing at the cathode interface are tracked by ultrasonic imaging, which leads to the capacity fading of SSBs. The ultrasonic imaging technology is demonstrated to be a powerful tool to evaluate the interfacial stability in SSBs, which can guide the rational design of interfaces and enhance the performance of SSBs.

Recent Advances in Battery Safety and Recycling. A Virtual Issue

“…In this context, ultrasonic technologies provide a facile approach to examining and observing interfaces in batteries, changes in contact between components, and even gas evolution in large battery formats (Figure 2). 16 Protecting the surface of active battery materials is key to ensure fast ion transport, electron transfer, and long cycle lifetimes. In Li-ion cells, capacity fade originates from either the formation of Li filaments and "dead" Li or the degradation of the cathode's bulk and/or surface structure.…”