Orbital-hybridization-driven electron transfer triggers the reductive susceptibility of solvated cyclic carbonates

Carbonate-based solvents are widely used in lithium-ion batteries due to their excellent solvation ability, high fluidity after blending, and the capability to form a solid electrolyte interphase (SEI) film through sacrificial reductive decomposition. However, as the core components of the electrolyte, the decomposition mechanism and microscopic influencing factors of cyclic carbonates remain unclear. To address this issue, this study employs multiple methods to comparatively investigate the properties and reduction behaviour of several cyclic carbonates. The results show that cyclic carbonates are more prone to reductive decomposition after forming solvation structures with lithium ions. Furthermore, influenced by molecular structure, the enhancement magnitude of the decomposition ability after solvation exhibits significant differences among different solvents. By analyzing the electronic structures and frontier orbitals, this paper reveals the microscopic mechanism: the leap in reduction ability in the solvated state essentially originates from the orbital hybridization effect between solvent molecules and the central lithium ion. This work clarifies how cyclic carbonates decompose via electron transfer, offering key theoretical insights to guide electrolyte optimization and electrode interface modification.