Demonstrating the Generality of Kerr-Gated Raman Spectroscopy Measurements of High Charge States in Graphitic Electrodes for Li-Ion Batteries

Abstract

Herein, the systematic application of the Kerr-gated Raman spectroscopy technique to track lithium intercalation into Li-ion graphite electrodes is reported under different operando, in situ, and ex situ experimental conditions with different graphitic electrode materials and electrolyte material formulations, through multiple cycles. The results revealed a broad generality of (i) the capability of the technique to resolve the characteristic G-band of graphite electrodes even at high charge states (high states of lithiation) and (ii) the sensitivity of the shift in the observed G-band to the state of electrochemical lithiation at high charge states during the transition from stage 2 to stage 1 (0.5 ≤ x ≤1 for LixC6). The shifted G-band was observed in highly lithiated electrodes comprising different graphite sources and conventional Li-ion-type electrolyte formulations and was further replicated using a noncommercial ionic liquid-based electrolyte formulation. Additionally, the persistence of the G-band (and the related shift as a function of charge) was replicated in many ex situ samples across 10 cycles, further evidencing the potential of this technique as a diagnostic tool to track high states of charge in cycled graphite-based negative electrodes for Li-ion batteries.