Fourier analysis of an electrochemical phase formation model enables the rationalization of zinc-anode battery dynamics

The efficiency of safe, cheap and sustainable zinc-anode batteries is critically affected by the time-dependent formation of surface films that can impede the utilization of the active material. Knowledge regarding the nature and, in particular, the dynamics of these films is strongly wanting and both theoretical and experimental tools to rationalize the empirically observed behaviour are poorly developed. The present investigation concentrates on the electrode oscillating behaviour and presents an original experimental monitoring approach - based on the joint measurement of electrical and optical quantities together with its physico-chemical modelling. The mathematical model considered is the DIB model of electrochemical phase formation, in its spatially homogeneous version: that is an ODE system coupling the dynamics of morphology and chemistry. The DIB parameters correspond to specific working conditions of the anode. Firstly, we analyse a Parameter Identification Problem (PIP) based on Fourier regularization. Secondly, a specific PIP is proposed for relaxation oscillations, based on the analysis of the geometry of the limit cycle. The results of this work allow a notable step forward in the understanding on zinc-anode instabilities and open up the perspective of closed-loop control of anode activity state, in view of battery control, also exploiting the higher sensitivity enabled by jointly transducing electrical and optical quantities.