Monitoring Dendrite Formation in Aqueous Zinc Batteries with SH0 Guided Waves

Metal dendrites can form on the electrode surface when a battery is repeatedly charged and discharged, this often results in reduced electrochemical performance and occasionally even internal short-circuiting. Hence, intensive research to study the underlying growth kinetics of dendrites in batteries has been initiated. However, existing technologies such as scanning electron microscopy and x-ray computed tomography are prohibitively expensive for in-operando monitoring. Recently, ultrasound-based techniques have become a promising alternative method for monitoring the health and status of battery cells. However, most of the reported ultrasonic methods utilise bulk waves which propagate through a laminated structure of cathode, anode, and electrolyte. In this study we use miniature transducers to excite fundamental shear-horizontal mode (SH0*) guided ultrasonic waves that propagate along an individual cathode and anode of an aqueous zinc ion battery. Coupled with optical microscopy, the cyclical variations of wave velocity and attenuation can be associated with the zinc strip-ping/plating phenomena that occur at the electrode surface. This demonstrates the sensitivity of the SH0* mode guided wave to dendrite formation at the electrode-electrolyte interface. More importantly, the findings suggest that measurements of guided ultrasonic waves may be used to quantitatively track dendrite growth in batteries.