Combined Stabilizing of the Solid-Electrolyte Interphase with Suppression of Graphite Exfoliation via Additive-Solvent Optimization in Li-Ion Batteries.

Abstract

Propylene carbonate (PC) is a promising solvent for extending the operating temperature range for lithium-ion batteries (LIBs) because of its high dielectric constant and wide temperature range stability. However, PC can cause graphite exfoliation through cointercalation, leading to electrolyte decomposition and subsequent irreversible capacity loss. This work reports the formulation of a ternary electrolyte with the introduction of an inorganic salt additive, potassium hexafluorophosphate (KPF6), to address the aforementioned concerns. We demonstrate the cumulative effect of solvent and additive on delivering multiple performance benefits and safety of the battery. The faster diffusion rate of K + solvation shell decreases the rate of PC decomposition, thereby reducing its cointercalation. Additionally, the optimum concentration of KPF6, i.e., 0.1 M constructs a robust and insoluble LiF-rich electrode/electrolyte interphase, further suppressing graphite exfoliation and Li dendrite formation. The stable cyclability is achieved by enhanced Li + transportation through the LiF-rich interphase, enabling an exfoliation-free and dendrite-free graphite anode in the ternary electrolyte.