Gurpreet Singh, an assistant professor of mechanical and nuclear engineering at Kansas State University in the US, has made a breakthrough in developing cheaper sodium ion batteries in the future.
Singh and his team have demonstrated that a composite paper - made of molybdenum disulfide and graphene nanosheets - can work both as an active material to efficiently store sodium atoms and a flexible current collector.
The composite paper can be used as a negative electrode in sodium-ion batteries - a boon for flexible batteries and supercapacitors.
In contrast to lithium, sodium supplies are essentially unlimited and the batteries are expected to be a lot cheaper.
Most negative electrodes for sodium-ion batteries use materials that undergo an 'alloying' reaction with sodium.
"These materials can swell as much as 400 to 500 percent as the battery is charged and discharged, which may result in mechanical damage and loss of electrical contact with the current collector," explained Singh.
"Molybdenum disulfide offers a new kind of chemistry with sodium ions," he added.
"The paper electrode offers stable charge capacity with respect to total electrode weight. Further, the interleaved and porous structure of the paper electrode offers smooth channels for sodium to diffuse in and out as the cell is charged and discharged quickly.
"This design also eliminates the polymeric binders and copper current collector foil used in a traditional battery electrode," he added.
The research marks the first time that such a flexible paper electrode was used in a sodium-ion battery as an anode that operates at room temperature.
Most commercial sodium-sulfur batteries operate close to 300 degrees celsius, Singh said.
The researchers are now working to commercialise the technology.
