Traditional lithium-ion batteries are prone to problems such as increased electrolyte viscosity, decreased ion conductivity, and sharp increase in interface charge transfer impedance in environments below -20°C, resulting in rapid battery performance degradation or even failure. Therefore, the simultaneous realization of efficient bulk ion transport and stable interface dynamics under extremely low temperature conditions has become a core problem that needs to be overcome in the field of low-temperature energy storage devices.
Recently, Ma Yanwei's team from the Institute of Electrical Engineering of the Chinese Academy of Sciences successfully developed a lithium-ion capacitor that can operate in an extremely low temperature environment of -100°C, breaking the low-temperature operation record of this type of device. The relevant results were published in "German Applied Chemistry".
Starting from the molecular structure design of the electrolyte solvent and the regulation of weak dipole interactions, the research team proposed a new low-temperature electrolyte design strategy.
By introducing a fluorinated group (-CF3) with a strong electron-withdrawing effect into the solvent molecules, the rigid solvation shell in the traditional electrolyte is broken, and a unique solvent-anion co-coordination weak aggregation structure (AGG-w) low-temperature electrolyte is constructed.
This weakly aggregated electrolyte not only maintains excellent bulk properties such as high ionic conductivity, low viscosity, and wide liquid range at low temperatures, but also achieves stable interfacial dynamics characteristics of low impedance and rapid transfer.
The 1100 F lithium ion capacitor prepared based on this new low-temperature electrolyte has successfully achieved stable discharge in an extremely low temperature environment of -100°C.
This research not only breaks through the application bottleneck of lithium-ion capacitors in extremely cold environments, but also lays a theoretical foundation for the development of high-performance electrochemical systems for extreme environments.It is of great significance to the implementation of my country's deep space exploration and polar strategy.
