Rechargeable Battery Electrolytes Capable of Operating over Wide Temperature Windows and Delivering High Safety

Abstract

self-discharge rates. [1-3] LIBs permeate nearly every aspect of human life. They are widely used in portable electronics (e.g., smartphones, smart-watches, and laptops), transportation (e.g., electric and hybrid vehicles), and biomedical applications (e.g., cardiac pacemakers and cochlear implants). In light of these achievements, J.B. Goodenough, M.S. Whittingham, and A. Yoshino won the 2019 Nobel prize in chemistry. [4] Despite the considerable success of conventional LIBs, their operational regime is typically around room temperature (RT). Operating at low (<0 °C) or high (>60 °C) temperatures usually deteriorate the performance and leads to safety risks. [5] We should also note that commercial LIBs are highly hazardous as they can ignite and explode in case of an accident, overheating, and overcharging, requiring more stringent safety standards, e.g., wide temperature operability and nonflammability. For example, electric vehicles require battery systems that can deliver a stable performance while maintaining a high energy density even in extreme climates, such as cold mountainous areas, where the temperatures can be as low as −40 °C, and hot deserts, where equipment exposed to sunlight can reach temperatures exceeding 70 °C. [6] Moreover, task-specific applications call for reliable energy storage solutions at extreme temperatures, including subsurface exploration (such as for mineral, oil, and gas), aerospace engineering, safety and rescue, and sterilizable medical devices. [2] Conventional LIBs are composed of a positive electrode or cathode (e.g., LiFePO 4 (LFP), LiNi x Mn y Co z O 2 (x + y + z = 1, NMC) and LiCoO 2 (LCO)), an electrolyte (including solvents, Li salts, and additives), a separator (typically a polyolefin membrane), and a negative electrode or anode (e.g., graphite and Li 4 Ti 5 O 12 (LTO)). Generally, the electrode materials are nonflammable and thermal stable (>300 °C). While the polyolefin membrane will melt/shrink over 120 °C, the commercial separators composited with ceramic nanoparticle (e.g., SiO 2 and Al 2 O 3) have been developed to reduce thermal shrinkage when exposed to overheating. [7,8] Therefore, the major challenge of commercial LIBs at extreme operating temperatures comes to the electrolyte. Carbonates are commonly used as solvents for conventional LIB electrolytes. However, these compounds are Li-ion batteries (LIBs) are the energy storage systems of choice for portable electronics and electric vehicles. Due to the growing deployment of energy storage solutions, LIBs are increasingly required to function safely and steadily over a broad range of operational conditions. However, the conventional electrolytes used in LIBs will malfunction when the temperatures fall below zero or elevate above 60 °C. Further, conventional electrolytes are toxic and flammable, leading to severe safety risks, especially in the case of an accident or overheating. Therefore, an ever-growing body of research has been dedicated to the development of electrolytes characterized by high ionic conduct...

Ultrathin and Non‐Flammable Dual‐Salt Polymer Electrolyte for High‐Energy‐Density Lithium‐Metal Battery

“…[16][17][18] In pursuit of LMBs with higher stability and safety, (quasi)solid-state electrolytes (SSEs) have been proposed as promising liquid electrolyte candidates. [19,20] Inorganic-based electrolytes (IBEs) generally have high ionic conductivity (up to 10 -2 S cm -1 ) at room temperature (RT), but the large interfacial impedance and poor processability hinder their practical applications. [21] Besides, the typical areal density (>100 mg cm -2 ) and thickness (>200 µm) of IBEs are both too high for high-energy-density LMBs.…”

Interface Aspects in All‐Solid‐State Li‐Based Batteries Reviewed

“…Essentially, these studies show that also ASSB are not intrinsically safe from a thermal point of view and therefore this topic deserves more attention. In various recent review papers, [ 174–176 ] the thermal performance of SE is discussed, indeed indicating that inorganic SE exhibit the highest safety level of which oxides‐based SE show the best thermal stability. It also should be noted that, in general, the onset temperature of individual components lies higher in comparison to the mixed components, such as SE with electrode material.…”

Thermally Stable and Nonflammable Electrolytes for Lithium Metal Batteries: Progress and Perspectives

“…Solid-state electrolytes are developed to avoid the battery failure induced by internal short circuits or leak. [97][98][99][100][101][102][103][104][105] Solid-state electrolytes include quasi and all-solid-state electrolytes. Although all-solid-state electrolytes theoretically achieve supreme b-d) Reproduced with permission.…”