(312a) Progress in Electro Acoustic Signal Analysis

We have recently determined a correlation between the acoustic time of flight and intensity and the structure, state of charge, and state of health of closed system electrochemical energy storage. We have shown that regardless of chemistry and geometry, an acoustic time of flight signal can be related to these properties of the cell.

Because a closed cell is effectively a mass redistribution reactor, and in a standard cell the volume is effectively fixed, the distribution of density within a battery must change as a function of state of charge and, along with density, the bulk moduli of the anode and cathode changes as well. The shifts in density and modulus also change the acoustic attenuation in a battery

In this presentation we will review the physical basis of our hypothesis and present progress in 1) correlating structural evolution and failure analysis with acoustic signal evolution, 2) present preliminary inverse models which describe the changes we see in the acoustic/state of charge response and 3) present â??physics freeâ? machine learning results to examine the uniqueness of an acoustic signal for a given battery in a given state of charge and health.