Schematic of designing and regulating eutectic electrolytes to form a stable solid electrolyte interphase.

Professor Xu Youlong from Xi'an Jiaotong University (XJTU), along with his team, has made significant achievements in the field of lithium metal batteries, successfully designing a non-flammable polymer-based deep eutectic electrolyte (PDEE). This new electrolyte significantly enhances battery safety and cycle life, marking an important step toward improving the energy density and safety of lithium metal batteries.

This breakthrough provides an alternative to using organic solvent electrolytes in current lithium metal batteries, which are prone to fires and explosions caused by short circuits or overcharging. By designing the non-flammable PDEE electrolyte, the team effectively improved battery stability, especially in terms of achieving uniform lithium deposition and extending cycle life.

Specifically, the team encapsulated a non-flammable N-methylacetamide (NMA) based deep eutectic electrolyte in a polymer framework through in situ polymerization. The strong interaction between the polar groups in LiNO₃ and NMA significantly improved the solubility of LiNO₃. By adjusting the amount of LiNO₃, they controlled the lithium deposition's ionization kinetics, ensuring uniform deposition and a higher lithium-ion exchange rate, which greatly extended the battery's lifespan. In experiments, the electrolyte demonstrated excellent electrochemical performance, with a capacity retention of 80.4 percent after 1000 cycles, showcasing its promise in pushing forward battery technology.

This research was recently published in the renowned international materials journal Advanced Functional Materials under the title "Solvation Regulation of Non-Flammable Polymer Deep Eutectic Electrolytes with Reinforced Inorganic-Rich Interphase toward Long-Cycle Lithium Metal Batteries".

Dr Yang Pu from the School of Electronic and Information Engineering, XJTU, is the first author of the paper, while Xu is the sole corresponding author.