Rapid anion transporting and mechanically robust cathode-electrolyte interphase for ultrafast and highly reversible dual-ion batteries within a wide temperature range

Abstract

High-voltage dual-ion batteries (DIBs) face significant challenges, including graphite cathode degradation, cathode-electrolyte interphase (CEI) instability, and the thermodynamic instability of conventional carbonate-based electrolytes, particularly at extreme temperatures. In this study, we develop a stable electrolyte incorporating lithium difluorophosphate (LiDFP) as an additive to enhance the electrochemical performance of DIBs over a wide temperature range. LiDFP preferentially decomposes to form a rapid anion-transporting, mechanically robust CEI layer on graphite, which provides better protection by suppressing graphite’s volume expansion, preventing electrolyte oxidative decomposition, and enhancing reaction kinetics. As a result, Li||graphite half cells using LiDFP electrolyte exhibit outstanding rate performance (90.8% capacity retention at 30 C) and excellent cycle stability (82.2% capacity retention after 5000 cycles) at room temperature. Moreover, graphite||graphite full cells with LiDFP electrolyte demonstrate stable discharge capacity across a temperature range of −20 to 40 °C, expanding the potential applications of LiDFP. This work establishes a novel strategy for optimizing the interphase through electrolyte design, paving the way for all-climate DIBs with improved performance and stability.