《High-Safety and High-Voltage Lithium Metal Batteries Enable by Nonflammable Diluted Highly Concentrated Electrolyte》

High-voltage lithium-metal batteries are expected to achieve energy densities of more than 400 Wh kg-1. However, the use of highly flammable organic electrolytes is a long-standing problem that can easily lead to safety hazards and greatly hinder the commercial application of lithium metal batteries. Therefore, we have developed a non-flammable dilution of high-concentration electrolyte (DHCE) with ethoxy (pentafluoro) cyclotriphosphine nitrogen (PFPN) as a diluent, while achieving high safety and cycling stability of high-voltage LMB. The electrolyte not only ensures the reversible deposition/dissolution behavior of the lithium metal anode (LMA) but also has an average coulombic efficiency (CE) of more than 99.1%. It also suppresses side reactions and stress cracks of lithium cobalt oxide (LCO) at high cut-off voltages. The developed DHCE has high thermal stability, shows complete non-flammability, and reduces the heat generation between the electrolyte and the circulating LCO and LMA. This work provides a rationale for the rational design of non-flammable electrolytes for high-voltage and high-safety LMBs.

http://https://doi.org/10.1016/j.nanoen.2023.1087