Lithium-metal batteries (LMBs) are interesting due to their high energy storage capacity. The development of suitable electrolytes is crucial to improving the safety and electrochemical properties of LMBs. Polyethylene oxide (PEO)-based polymer electrolytes could be good candidates due to their excellent lithium-ion migration capabilities. However, PEO is flammable and shows high crystallinity at room temperature. One strategy for improving those drawbacks is to introduce functional additives.

Yu-Hang Zhang, Shenyang University of Technology, China, and colleagues have developed a PEO-based polymer electrolyte (pictured below) with low price and high flame-retardant efficiency. To achieve this, the team introduced triethyl phosphate (TEP) into PEO as a flame retardant, together with the film-forming additive fluoroethylene carbonate (FEC) and the crosslinking agent tetramethylene glycol dimethyl ether (TEGDME) using a simple UV curing method. Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) was used as the lithium source and 4-methyldibenzophenone (MBP) as a photoinitiator.

 

 

The resulting PEO-based electrolyte shows enhanced safety and excellent room-temperature properties. It can quickly self-extinguish after igniting due to the presence of TEP and the non-flammability of FEC. The team found that LiFePO₄||Li cells using the electrolyte show a high average discharge capacity and lifespan (over 500 cycles at 0.5 C).

---

• Self‐Extinguishing and Low‐Cost Quasi‐Solid Polymer Electrolyte for Room Temperature Lithium Metal Batteries,
  Xue-Tong Hu, Shuang Chen, Peng-Fei Wang, Yuhan Wu, Fa-Nian Shi, Yu-Hang Zhang,
  Batteries Supercaps 2024.
  https://doi.org/10.1002/batt.202400118