An ambiguity of laser‐induced degradation in LiFePO4 and advantages of single‐particle approach to Raman spectroscopy

Laser‐induced degradation is a common issue for the Raman spectroscopy study of lithium battery materials. In this work, the combination of single‐particle Raman measurements with scanning electron microscope imaging helped us reveal the variation of the decomposition pathways and products. For the first time, we observed possible laser‐induced melting of the LiFePO4 particles and an unidentified decomposition product, an alternative to previously reported α‐Fe2O3 and γ‐Li3Fe2(PO4)3. These results and analysis of the time series of Raman measurements raise doubts about laser‐induced heating. We suppose non‐thermal amorphization and melting processes due to electronic system excitation by intraband transitions with the following covalent bond destabilization. The role of defects in laser‐induced decomposition is discussed. We hope that this article could help develop a non‐destructive tool for quality control and the study of the electrochemical or thermal degradation of LiFePO4. The combination of single‐particle Raman measurements with SEM imaging revealed the variation of the decomposition pathways and products of LiFePO4. For the first time, we observed possible laser‐induced melting of studied particles and an unidentified decomposition product. The obtained results and analysis of the time series of Raman measurements let us suppose non‐thermal amorphization and melting processes due to electronic system excitation with the following covalent bond destabilization.