Impact of Low Temperatures on the Lithiation and Delithiation Properties of Si-Based Electrodes in Ionic Liquid Electrolytes

Abstract

Lithium-ion batteries are used in various extreme environments, such as cold regions and outer space; thus, improvements in energy density, safety, and cycle life in these environments are urgently required. We investigated changes in the charge and discharge properties of Si-based electrodes in ionic liquid electrolytes with decreasing temperature and the cycle life at low temperature. The reversible capacity at low temperature was determined by the properties of the surface film on the electrodes and/or the ionic conductivity of the electrolytes. The electrode coated with a surface film formed at a low temperature exhibited insufficient capacity. In contrast, a Si-only electrode precoated with the surface film at room temperature exhibited a cycle life at low temperatures in ionic liquid electrolytes longer than that in conventional organic liquid electrolytes. Doping phosphorus into Si led to improved cycling performance, and its impact was more noticeable at lower temperatures.

Recent Advances in Electrolytes for Enabling Lithium-Ion Batteries across a Wide Temperature Range

“…). 44 The 1 M LiFSA/ [Py13][FSA] ionic liquid electrolyte demonstrated ionic conductivities of 6.4, 1.9, and 0.5 mS cm −1 at 30, 0, and −20 °C, respectively, while 1 M LiFSA/[EMI][FSA] demonstrated 13.6, 4.6, and 1.4 mS cm −1 at the same temperatures (Figure 3c). For comparison, the organic liquid electrolyte 1 M LiPF 6 in EC:DEC ( ) as an additive in the organic liquid electrolyte 1 M LiPF 6 in EC/EMC (1:2, wt %) to improve the low-temperature cycling performance of NMC532||graphite batteries.…”

“…(d) Discharge capacity of Li||Si cells cycled at various temperatures at 1C in various electrolytes with a charge capacity limitation of 1000 mAh g –1 . Reprinted with permission from ref . Copyright 2022 American Chemical Society.…”

“…(c) Conductivity of the selected electrolytes. Reprinted with permission from ref . Copyright 2022 American Chemical Society.…”

Advances in Low‐Temperature Dual‐Ion Batteries

“…IL‐based electrolytes have attracted great attentions for rechargeable batteries due to their wide electrochemical stability windows, negligible volatility, low flammability, and exclusion of solvent co‐intercalation [63–66] . Specially, the [EMIm]Cl–AlCl 3 ILs with different molar ratios had been employed in all‐climate AIBs based on graphitic carbon cathodes [54–56] .…”

“…IL-based electrolytes have attracted great attentions for rechargeable batteries due to their wide electrochemical stability windows, negligible volatility, low flammability, and exclusion of solvent co-intercalation. [63][64][65][66] Specially, the [EMIm]Cl-AlCl 3 ILs with different molar ratios had been employed in all-climate AIBs based on graphitic carbon cathodes. [54][55][56] However, higher freezing point and viscosity of solvent-free IL electrolytes than conventional organic solvents made them much less suitable for ultra-low temperature operation.…”