A new electrolyte could make the sodium metal battery safer and longer-lasting, according to researchers at Chonnam National University in South Korea. The team, led by Professor Chan-Jin Park of the Department of Materials Science and Engineering, developed a non-flammable, leak-proof electrolyte that kept a pouch cell powering an LED even after it was folded and cut.
The study, titled “Noncovalent interaction-regulated polymerizable deep eutectic solvent electrolyte for sodium metal batteries,” was made available online on August 2, 2026, and published in Volume 90 of Energy Storage Materials.
Why the sodium metal battery needs a better electrolyte
Sodium-metal batteries are gaining attention as a next-generation energy storage technology because sodium is abundant and low-cost, making them a potential alternative to commercial lithium-ion batteries. But practical use is limited by safety and stability problems.
Sodium metal is highly reactive. It can grow dendrites, needle-like deposits that shorten battery life, and it can trigger unwanted side reactions. At scale, high operating temperatures can cause catastrophic failure. Conventional organic liquid electrolytes add to the risk because they are volatile, highly flammable and toxic.
How the new electrolyte is made
The Chonnam team built a polymerizable deep eutectic solvent (PDES) electrolyte from three ingredients, each with its own job:
- Sodium perchlorate (NaClO4): the source of sodium ions, chosen because the perchlorate anion binds weakly to sodium, which helps the salt dissociate.
- N-isopropylacrylamide (NIPAM): promotes sodium-ion dissociation through ion-dipole interactions and forms a robust polymer matrix.
- Succinonitrile (SN): adds plasticity and further helps sodium ions dissociate.
Mixed together, these form a deep eutectic solvent, a uniform liquid held together by hydrogen bonding and ion-dipole interactions. Such solvents are non-flammable and chemically and thermally stable, but as electrolytes they tend to leak. To solve that, the researchers polymerized the mixture in place inside the cell, turning it into a sturdier, leak-free solid matrix.
“Our electrolyte combines efficient Na ion transport with improved safety, leakage resistance and interfacial stability, making it a promising candidate for practical sodium-metal batteries,” Park said.
Sodium metal battery test results
The optimized electrolyte reached an ionic conductivity of 1.39 mS/cm at 30°C and a sodium-ion transference number of 0.58, with a wide electrochemical stability window. It also showed strong flame retardance on direct exposure to fire and resisted leakage.
In full cells, the electrolyte formed a robust interface on the cathode during cycling, suppressing side reactions and irregular sodium growth. The results included:
- An initial discharge capacity of 110.2 mAh/g at 0.1C, with nearly 99% coulombic efficiency
- 90.4% capacity retention after 1,000 cycles at a 2C rate
- A pouch cell that kept an LED lit even when folded and cut
Where this could be used
The researchers see applications in grid-level renewable energy storage, backup power systems and low-cost rechargeable batteries. “Our electrolyte design for SMBs can lead to safer, lower-cost and more sustainable rechargeable batteries,” Park said.
These are lab-scale results. The release does not give a timeline for commercial cells or report tests at large pack sizes.
As a writer, I think the folded-and-cut pouch cell demo is the detail that makes this work stand out, since fire risk is the first question anyone asks about a new battery chemistry. For more battery research, see our stories on a zinc battery electrolyte built on carnosine, Harvard’s 500 Wh/kg solar aircraft battery target and Rio Tinto’s Rondo heat battery.
FAQ
What is a sodium metal battery?
It is a rechargeable battery that uses sodium metal as the anode. Sodium is abundant and cheap, but the metal is highly reactive, which creates safety and stability challenges.
What makes the Chonnam electrolyte safer?
It is a polymerized deep eutectic solvent that is non-flammable and leak-proof, unlike the volatile, flammable organic liquids used in conventional electrolytes.
How long did the test cells last?
A full cell kept 90.4% of its capacity after 1,000 charge cycles at a 2C rate.