Aging Mechanisms of Electrodes in LiFePO4/Graphite Batteries

In the last decade, lithium-ion batteries (LIBs) have become ubiquitous in many technological fields. However, their diagnostics and remaining lifetime estimation are far from being established. To this end, an important aspect is establishing a correlation between the physical changes occurring to the battery materials upon aging and the data obtained by non-destructive measurements. In this paper, we report a methodology for post-mortem analysis of LiFePO4/Graphite batteries involving a range of experimental techniques, including scanning electron microscopy, Raman spectroscopy, and electrochemical impedance spectroscopy, as well as some preliminary results on the correlation of observed microscopic changes and aging parameters. In particular, a larger cycle depth and higher average state-of-charge led to increased battery degradation manifested as morphological and composition changes in anode and cathode, respectively.