In-Operando X-ray Tomography Studies of Dendrite Formation in Zinc-Air Batteries

Rechargeable aqueous zinc-air systems are remarkably attractive power sources because of high specific energy, safety, environmental compatibility and low cost. However these systems are still under development and suffer from sufficiently short cycle life that prohibits their use for large electrical storage applications requiring several thousand cycles.  One of the key factors responsible is dendritic growth when the system is recharged. Dendrites can grow sufficiently wide to penetrate the separator between the anode and the cathode and cause an internal short-circuit. Despite the substantial work accomplished in studying of zinc dendrite formation there are only few reports available on real time imaging of dendrite growth.

Recent developments in X-ray micro/nano tomography have demonstrated the great advantage of the technique for non-destructive ex- and in-situ characterisation of materials and devices for electrochemical energy storage and generation. We used synchrotron x-ray tomography to investigate the mechanism and kinetics of dendrite formation during zinc-air system operation. The dendrite growth was analysed in-operando in radiography mode while three-dimensional image of dendrites covering the electrode surface was reconstructed from multiple tomographic projections ( Figure 1).