Temperature-Responsive Solvation of Deep Eutectic Electrolyte Enabling Mesocarbon Microbead Anode for High-Temperature Li-Ion Batteries

Abstract

Deep eutectic electrolytes (DEEs) provide a safe solution for high-temperature batteries. While promising, the DEEs/electrode interphase chemistry and the underlying temperature mechanism remain unclear. Herein, the DEE is formulated with succinonitrile (SCL) and lithium bis­(fluorosulfonyl) imide (LiFSI) to promote the mesocarbon microbead (MCMB) anode in high-temperature Li-ion batteries. The temperature-sensitive mechanism of solid electrolyte interphase (SEI) evolution on the MCMB is deciphered, the core of which is temperature-regulated solvation chemistry. Specifically, high temperature can result in the enhanced interaction between Li+ and FSI– anions in the solvation structure, thus elevating the LiF content in the SEI. Due to the synergy of DEE (featuring rapid ion conduction and thermal stability) and high-temperature optimized interphase, MCMB/Li and LiFePO4/MCMB cells exhibit improved cycling stability at high temperature. This work promotes a fundamental understanding of the intrinsic relationship between the temperature factor and SEI evolution, illuminating the future of DEEs in high-temperature batteries.

Electrolyte Engineering with Tamed Electrode Interphases for High‐Voltage Sodium‐Ion Batteries

“…Further, the deconvolution of C≡N bands in the electrolyte solutions of SN-FEC and DEC-SN-FEC shows an additional peak at 2264 cm −1 (green peak), indicating the participation of SN in Na + solvation by C≡N•••Na + coordination. [27,28] The observation is further supported by 23 Na NMR spectroscopy (Figure 1i). The downfield shift (more positive) of the 23 Na chemical shift in SN-FEC compared to the EC-PC electrolyte implies weaker solvation for Na + by SN molecules.…”

Eutectic Electrolytes Convoying Low-Temperature Metal-Ion Batteries

“…Figure comprehensively illustrates the “arched-window” structured design for constructing novel eutectic electrolytes, where extensive attention is paid to the relationship among anion categories and Lewis base choice, eutectic thermodynamic and model construction, eutectic electrolyte–interphase chemistry, and liquid preservation ability at low temperatures. This figure provides a favorable prospect for the grid-scale implementation of metal-ion storage devices. , The change of solvation structure and SEI under sub-zero temperature is beneficial to deepen the understanding of the eutectic interactions and illuminate the eutectics’ future . Moreover, the electrolyte must simultaneously cooperate with all other battery components (cathode, anode, current collector, and separator).…”

Unraveling the temperature-responsive solvation structure and interfacial chemistry for graphite anodes

“…25–28 Moreover, the variation of the temperatures can induce the corresponding changes in the coordination interaction of Li + with solvents and anions, leading to the transformation of the primary solvation structure of Li + . 29–32 The interaction between the electrolyte and the SEI becomes even more complex because the SEI formation process is closely linked to the reduction stability of the solvated components, especially when thermal reduction interferes at elevated temperature. 13,33 This highlights the significant effect of temperature on the solvation sheath and SEI film.…”