Optimize Lithium Deposition at Low Temperature by Weakly Solvating Power Solvent

Abstract

For lithium (Li) metal batteries, the decrease in operating temperature brings severe safety issues by more disordered Li deposition. Here, we demonstrate that the solvating power of solvent is closely related to the reversibility of the Li deposition/stripping process under low-temperature conditions. The electrolyte with weakly solvating power solvent shows lower desolvation energy, allowing for a uniform Li deposition morphology, as well as a high deposition/stripping efficiency (97.87 % at À 40 °C). Based on a weakly solvating electrolyte, we further built a full cell by coupling the Li metal anode with a sulfurized polyacrylonitrile electrode at a low anode-to-cathode capacity ratio for steady cycling at À 40 °C. Our results clarified the relationship between solvating power of solvent and Li deposition behavior at low temperatures.

Molecular/Ionic Designs in the Electrolyte and Interphases for Lithium Metal Anode

“…The principle of decreasing the binding energy between Li + and solvent to facilitate the de-solvation process is also mirrored in low-temperature LMBs based on ether solvents. [25,84] The Liu group discovered that although diethyl ether (DEE) electrolyte has a lower ionic conductivity than DOL/DME electrolyte, DEE electrolyte exhibited a higher CE and superior cycle capacity and lifetime at low temperatures. [25] It demonstrates that the de-solvation process may be more significant than conductivity in determining battery performance at low temperatures.…”

“…Similarly, the Tao group developed a novel low-temperature electrolyte based on dimethoxymethane (DMM) for LMBs. [84] The results of density functional theory (DFT) calculations indicate that DMM solvent molecules have low de-solvation energy and a tendency to generate an inorganic-rich SEI on the Li metal anode. The experimental results demonstrate that more uniform and dense Li metal deposition can be detected in the DMM electrolyte and Li j j Cu cells at temperatures ranging from room temperature to À 40 °C exhibit high levels of reversible Li plating/ stripping behavior.…”

Low‐Temperature and High‐Areal‐Capacity Rechargeable Lithium Batteries enabled by π‐Conjugated Systems

“…[5][6][7][8] At low temperature, the ionic diffusion is largely restrained due to an insufficient dynamics, leading to a rapid decrease in capacity, rate capability and cyclic stability. [9][10][11] Recently, many works have been devoted to enhance the ionic diffusion rate within the bulk electrode at low temperature through electrodestructure design, but it inevitably sacrifices the mass loading of active materials and thus a decreased energy density. [12][13][14] Hence, it is a challenge to develop high-areal-capacity rechargeable LIBs at low temperature.…”

“…However, owing to the significant decrease in the ionic and electronic conduction of the thick electrode, high mass loading electrodes usually undergo sluggish kinetics and low utilization of active materials, which will be deteriorated when the operating temperature drops below 0 °C [5–8] . At low temperature, the ionic diffusion is largely restrained due to an insufficient dynamics, leading to a rapid decrease in capacity, rate capability and cyclic stability [9–11] . Recently, many works have been devoted to enhance the ionic diffusion rate within the bulk electrode at low temperature through electrode‐structure design, but it inevitably sacrifices the mass loading of active materials and thus a decreased energy density [12–14] .…”

An Ultrafast and Stable Li‐Metal Battery Cycled at −40 °C

“…[10][11][12][13] Moreover, the reduced sizes of Li nuclei at low temperatures (LT) will make the exposure Li anode to the electrolyte more possible, inducing parasitic reactions, which is also unfavorable for stable operation of LMBs at LT. [2,11,[14][15][16][17] Many efforts have been devoted to stabilize Li metal anode at LT, including constructing artificial SEI film, [18] engineering current collectors, [19] modifying separator, [20] optimizing solvent component, [21][22][23] and introducing additives. [24][25][26][27][28] Although some strategies are efficient for stabilizing LMBs, [29][30][31][32] simultaneously achieving high-rate performance and stable cycling in LMBs at LT still remains a great challenge.…”