New Non-Flammable Solid Electrolyte Could Unlock Safer, Cheaper Grid-Scale Sodium Batteries

Researchers at the University of Queensland's Australian Institute for Bioengineering and Nanotechnology (AIBN) report a promising advance for large-scale battery storage: a fluorinated block copolymer solid electrolyte, P(Na3-EO7)-PFPE, that is non-flammable and suppresses dendrite growth — two major obstacles for sodium metal batteries (SMBs).

The material behaves like a plastic, providing mechanical stability while blocking the metal filaments (dendrites) that can penetrate electrolytes and cause short circuits. In laboratory tests, an SMB containing the polymer electrolyte ran continuously for more than 5,000 hours at 176°F (≈80°C) and retained over 91% of its capacity after 1,000 charge cycles.

Why this matters: SMBs use sodium, which is far more abundant and less expensive than lithium, making them an attractive option for grid-scale storage where cost and sustainability are paramount. However, safety risks from flammable liquid electrolytes and performance shortfalls at room temperature have limited adoption. A solid, non-flammable electrolyte that also inhibits dendrites could address both concerns.

"This kind of long-term performance is essential for grid-level energy storage," said AIBN Group Leader Dr. Cheng Zhang, emphasizing the importance of durability for utility-scale deployment.

AIBN PhD student Zhou Chen, who helped develop the polymer alongside Dr. Zhang, combined computational modeling with hands-on engineering experience to design and evaluate the material. The team notes that the next critical challenge is improving ionic conductivity and efficiency at normal operating (room) temperatures to make the technology commercially viable.

Other research groups are advancing complementary sodium solid-state approaches: teams at the University of Maryland have reported encouraging room-temperature results for a sodium-based solid-state cell, and researchers at the University of Chicago have developed a crystallized sodium hydridoborate solid electrolyte that performs reliably from room temperature down to sub-freezing conditions.

Implications and next steps

If the University of Queensland polymer can be optimized for higher conductivity at ambient temperatures and scaled economically, it could enable safer, lower-cost grid batteries that reduce dependence on lithium and mitigate environmental impacts associated with lithium extraction. Continued work will be needed to validate performance across larger cells, evaluate long-term stability under varied real-world conditions, and confirm manufacturing feasibility.

Bottom line: The P(Na3-EO7)-PFPE solid electrolyte is a significant materials advance for sodium metal batteries, showing strong safety and longevity indicators in lab tests. Improving room-temperature efficiency and scaling the material are the crucial next steps toward practical, grid-scale deployment.