Tackling application limitations of high-safety γ-butyrolactone electrolytes: Exploring mechanisms and proposing solutions

Developing wide-temperature and high-safety lithium-ion batteries (LIBs) presents significant challenges attributed to the absence of suitable solvents possessing broad liquid range and non-flammability properties. γ-Butyrolactone (GBL) has emerged as a promising solvent; however, its incompatibility with graphite anode has hindered its application. This limitation necessitates a comprehensive investigation into the underlying mechanisms and potential solutions. In this study, we achieve a molecular-level understanding of the perplexing interphase formation process by employing in-situ spectroelectrochemical techniques and density function calculations. Our findings reveal that, even at high salt concentrations, GBL consistently occupies the primary Li+ solvation sheath, leading to extensive GBL decomposition and the formation of a high-impedance and inorganic-poor solid-electrolyte interphase (SEI) layer. Contrary to manipulating solvation structures, our research demonstrates that the utilization of film-forming additives with higher reduction potential facilitates the pre-establishment of a robust SEI film on the graphite anode. This approach effectively inhibits GBL decomposition and significantly enhances the battery's lifespan. This study provides the first reported intrinsic understanding of the unique GBL-graphite incompatibility and offers valuable insights for the development of wide-temperature and high-safety LIBs.