Single-oxygen linear ether (SOLE) based electrolytes for fast-charging and low-temperature Li-ion batteries

Abstract

With the proliferation of electric vehicles, next-generation lithium-ion batteries (LIBs) need to satisfy the requirements of both fast charging and low-temperature operation. As a key component in LIBs, the electrolyte dictates the electrode–electrolyte interfacial properties and the bulk transport properties, thereby crucially governing LIBs' performance. Due to their reasonable polarity, low viscosity and good cathodic stability, ether solvents are widely used in Li metal batteries (Li/S, Li/air, etc.). However, due to their co-intercalation problem, ether solvents are seldom used in LIBs. In this work, we report a series of electrolytes based on single-oxygen linear ether (SOLE), which show great compatibility with the graphite anode at the normal salt concentration (1 m and ∼0.7 M) and better fast-charging and low-temperature performances than commercial electrolytes. Such superior fast-charging and low-temperature performance is attributed to the low interfacial resistance and low viscosity. Graphite (Gr) | LiFePO₄ (LFP) full cells with example SOLE electrolytes show very good cycling stability with a capacity retention of 77.3% after 1000 cycles. The Raman spectroscopy results show that due to the low polarity of SOLEs, SOLE electrolytes contain a significant amount of contact ion pairs (CIPs) and aggregates (AGGs) similar to high concentration electrolyte (HCE) and localized high concentration electrolyte (LHCE). The X-ray photoelectron spectroscopy results show these electrolytes form LiF-rich solid electrolyte interphase (SEI). This work opens a new avenue to design LIBs electrolytes for extremely fast charging and low-temperature performance without sacrificing cycling stability.