Toward Low‐Temperature Lithium Batteries: Advances and Prospects of Unconventional Electrolytes

Abstract

Lithium batteries have been widely used in various fields such as portable electronic devices, electric vehicles, and grid storages devices. However, the low temperature‐tolerant performances (−70 to 0 °C) of lithium batteries are still mainly hampered by low ionic conductivity of bulk electrolyte and interfacial issues. In general, there are four threats in developing low‐temperature lithium batteries when using traditional carbonate‐based electrolytes: 1) low ionic conductivity of bulk electrolyte, 2) increased resistance of solid electrolyte interphase (SEI), 3) sluggish kinetics of charge transfer, 4) slow Li diffusion throughout bulk electrodes. Meanwhile, conventional electrolytes have been close to the upper limit of optimum low‐temperature performance owing to their intrinsic molecular structural properties. As a result, it is urgent to design unconventional electrolytes with lower melting point and higher ionic conductivity. Herein, the recent key advances in regard to unconventional electrolytes including fluorinated ester, ethyl acetate, gamma‐butyrolactone, liquefied gas, ether, plastic crystal, and aqueous electrolytes are overviewed. Solvation structure modification and SEI optimization of unconventional electrolytes for low‐temperature lithium batteries are focused. Finally, aiming at the deficiencies in current understanding, the inherent limitations and envision the future prospects of low‐temperature lithium batteries are explored.

Electrolyte design implications of ion-pairing in low-temperature Li metal batteries

“…Though our previous results have indicated exceptional ionic conductivity is not necessarily a prerequisite for reversible low temperature Li metal performance, 23 the freezing of electrolytes and exponential increases in their viscosity is known to overwhelm electrochemical performance. 11,21 As shown in Fig. 2a, it was confirmed that all systems of interest remained in a liquid state down to À60 1C.…”

“…Historically, improving the bulk ionic conductivity, solid-electrolyte interphase (SEI) composition, and Li + charge-transfer penalty have been the foremost goals of low temperature electrolyte design. 3,4,[9][10][11][19][20][21] Among these factors, it has been suggested that the charge-transfer penalty is the dominant limitation among systems with sufficient bulk transport. 2,22,23 However, the heterogenous charge-transfer process in electrochemical systems is invariably complicated, particularly given that there is no mechanistic consensus regarding Li + dynamics at the electrode interphase in the presence of a SEI.…”

Low-temperature lithium-ion batteries: challenges and progress of surface/interface modifications for advanced performance

“…Some researchers have summarized the current developments in low-temperature LIBs from different perspectives, such as the development of electrode materials, the design of electrolytes and the exploration of novel battery systems. 10,12,[23][24][25] Besides electrodes and electrolytes, more attention should be paid to the electrode/electrolyte interface, [26][27][28][29] considering that interfacial charge transfer resistance accounts for the majority of cell resistance at subzero temperatures. Since the charge transfer process occurs at the electrode/electrolyte interface, the surface/interface properties greatly influence the charge transfer kinetics, as well as the corresponding low-temperature performance of LIBs.…”

Tailoring Electrolytes to Enable Low-Temperature Cycling of Ni-Rich NCM Cathode Materials for Li-Ion Batteries

“…The research and development of high-performance low-temperature batteries can not only break through the application limitations of lithium-ion batteries in extremely cold environments (high latitudes and aerospace applications) but also greatly promote the development of electric vehicles. The reasons for the low-temperature performance degradation of lithium-ion batteries are as follows: , first, the diffusion rate of Li + in the positive and negative electrodes is limited at low temperatures. Second, the viscosity of the lithium-ion battery electrolyte increases at low temperature due to the high melting point (e.g., 36–38 °C) of the main solvent in the electrolyte .…”