A simple method of electrochemical lithium intercalation within graphite from a propylene carbonate-based solution

Abstract

Electrochemical lithium intercalation within graphite from 1moldm−3 solution of LiClO4 in propylene carbonate (PC) was investigated at 25 and −15°C. Lithium ions were intercalated into and de-intercalated from graphite reversibly at −15°C despite the use of pure PC as the solvent. However, ceaseless solvent decomposition and intense exfoliation of graphene layers occurred at 25°C. The results of the Raman spectroscopic analysis indicated that the interaction between PC molecules and lithium ions became weaker at −15°C by chemical exchange effects, which suggested that the thermodynamic stability of the solvated lithium ions was an important factor that determined the formation of a solid electrolyte interface (SEI) in PC-based solutions. Charge–discharge analysis revealed that the nature of the SEI formed at −15°C in 1moldm−3 of LiClO4 in PC was significantly different from that formed at 25°C in 1moldm−3 of LiClO4 in PC containing vinylene carbonate, 3.27molkg−1 of LiClO4 in PC, and 1moldm−3 of LiClO4 in ethylene carbonate.