Safe and Stable Lithium Metal Batteries Enabled by an Amide-Based Electrolyte

Abstract

Highlights A novel amide-based nonflammable electrolyte is proposed. The formation mechanism and solvation chemistry are investigated by molecular dynamics simulations and density functional theory. An inorganic/organic-rich solid electrolyte interphase with an abundance of LiF, Li3N and Li–N–C is in situ formed, leading to spherical lithium deposition. The amide-based electrolyte can enable stable cycling performance at room temperature and 60 ℃. Abstract The formation of lithium dendrites and the safety hazards arising from flammable liquid electrolytes have seriously hindered the development of high-energy-density lithium metal batteries. Herein, an emerging amide-based electrolyte is proposed, containing LiTFSI and butyrolactam in different molar ratios. 1,1,2,2-Tetrafluoroethyl-2,2,3,3-tetrafluoropropylether and fluoroethylene carbonate are introduced into the amide-based electrolyte as counter solvent and additives. The well-designed amide-based electrolyte possesses nonflammability, high ionic conductivity, high thermal stability and electrochemical stability (> 4.7 V). Besides, an inorganic/organic-rich solid electrolyte interphase with an abundance of LiF, Li3N and Li–N–C is in situ formed, leading to spherical lithium deposition. The formation mechanism and solvation chemistry of amide-based electrolyte are further investigated by molecular dynamics simulations and density functional theory. When applied in Li metal batteries with LiFePO4 and LiMn2O4 cathode, the amide-based electrolyte can enable stable cycling performance at room temperature and 60 ℃. This study provides a new insight into the development of amide-based electrolytes for lithium metal batteries.

Applying Classical, Ab Initio, and Machine-Learning Molecular Dynamics Simulations to the Liquid Electrolyte for Rechargeable Batteries

“…Cations are small in size with high positive charge densities, and aprotic polar solvents commonly used in electrolytes possess strong nucleophilic sites (e.g., carbonyl oxygen). Therefore, solvents have the potential to compete with anions for the cation solvation, − forming solvation shells in electrolytes (Figure a). This phenomenon has been verified by many experimental characterizations. − MD simulations allow a concrete observation of the solvation structures of cations at the microscopic level (Figure b) .…”

A Competitive Solvation of Ternary Eutectic Electrolytes Tailoring the Electrode/Electrolyte Interphase for Lithium Metal Batteries

“…The formation mechanism of ternary eutectic electrolytes was investigated using FTIR and Raman spectroscopies. For binary eutectic electrolytes (Figures f,g and Figure S6a), the IR peak of LB at 3236 cm –1 (NH stretching vibration of BL) disappeared, indicating that no free BL solvent molecules were present in the electrolyte . For ternary eutectic electrolytes (Figure S6b), the bands at 1656 cm –1 (CO stretching vibration) and 1179 cm –1 (CF 3 stretching vibration) shifted to 1671 and 1187 cm –1 with the increasing SN content, indicating that SN may have an influence on the interaction between LiTFSI and BL.…”

Liquid-Free Ion-Conducting Elastomer with Environmental Stability for Soft Sensing and Thermoelectric Generating

“…Like the mechanical properties, there is almost no significant change in the FTIR-ATR spectra under the addition of a small amount of LiTFSI (from 0 to 0.01 mol L –1 ). With substantially increasing the content of LiTFSI, FTIR-ATR spectra present conspicuous variations, some new characteristic bonds appeared, and their intensities are growing, including S–N–S at 1055 cm –1 , C–SO 2 –N at 1135 and 1351 cm –1 , and C–F at 740, 1137, and 1185 cm –1 . , Moreover, the stretching vibrations of C–O–C at 1097 cm –1 and CO at 1715 cm –1 show arresting shifting tendency to lower wavenumbers with the addition of lithium salt, which can be attributed to the coordination between C–O–C and CO groups of WPU with Li + of LiTFSI . The XRD patterns of LiTFSI and representative LFICEs are shown in Figure b.…”