Australian researchers develop safer electrolyte for sodium batteries

Researchers from Deakin University in Victoria and the University of Queensland say they have developed a new and non-flammable electrolyte material for use in sodium batteries that could make the technology safer and cheaper than lithium-ion batteries.

The breakthrough development, reported this month in the journal Nature Materials, is the creation of a solid polymer electrolyte material which replaces the flammable liquid solvents traditionally used in sodium batteries.

“Most industries that develop sodium batteries generally use carbon-based electrode and liquid electrolyte, which has low capacity and also can fuel a fire if the battery overheats,” said Dr Xiaoen Wang, who led the research alongside Professor Maria Forsyth, also from Deakin University’s Institute for Frontier Materials.

“We are taking a different approach, using reactive sodium metal as an anode to increase battery capacity and in the process are developing safer electrolytes to ensure the safety of sodium batteries.”

However, it was a key component – a fluorine-containing polymer – developed by Dr Cheng Zhang and Professor Andrew K. Whittaker based at the University of Queensland’s Australian Institute for Bioengineering and Nanotechnology that provided an important breakthrough.

Originally used for biological applications, this is the first time that a fluorine-containing class of polymer will be used in solid state sodium batteries.

Battery development has raced along over the last decade and continues to accelerate as researchers and scientists around the globe search for alternatives to traditional lithium-ion batteries due to the diminishing resources required in manufacturing.

“As lithium could become a rare commodity, the price of lithium batteries is high, while on the other hand, sodium resources are more abundant,” said Dr Wang.

“Our polymer will support the use of sodium batteries, which are low cost when compared to lithium batteries.”

Previously, though, sodium batteries did not last as long as lithium-ion batteries, nor did they have as high an energy density, meaning that the only upside existed in the manufacturing and supply.

By pairing sodium batteries with the new polymer electrolytes, though, the researchers believe that sodium batteries could offer close to 1,000 cycles – comparable to current lithium-ion batteries.

The researchers also believe that further study could open the door for their new sodium batteries to be used in stationary energy storage or even in electric vehicles. Small-scale testing of the batteries has already been successful, and the researchers are looking to upscale testing, before moving towards prototyping.