Researchers at Kansas State University have developed a new composite paper electrode for use in sodium-ion batteries, potentially revolutionizing the design of sodium-ion batteries and getting them one step closer to the market.
All batteries are composed of three primary components – a cathode, an anode and an electrolyte – which must be tailored to accommodate the specific chemical reactions that will make the battery perform at its highest capacity. While lithium-ion battery technology has been well developed and tasted wide commercial success over the years, sodium-ion technology has lagged behind due to the difficulty of making a suitable anode.
According to Dr. Gurpreet Singh, an assistant professor at Kansas State University, most anodes used for sodium-ion batteries can swell by “as much as 400% to 500% as the battery is charged and discharged” due to the unique chemistry in sodium-ion batteries. This resulting stress can lead to electrical failure and cause mechanical damage to the battery in only a few charge-discharge cycles, making them unattractive for practical applications.
Singh has adopted a new anode design, using interleaved layers of molybdenum disulfide and graphene nanosheets to create a paper-like composite material that is not only swell-free and flexible but also has high mechanical durability. This work, published in the ACS Nano (a scientific journal), represents the first time the composite nano-material has been fabricated as well as the first time it has been applied to sodium-ion batteries. The researchers are hoping to further explore the use of these and other nanomaterials for lithium and sodium-based battery storage.
Sodium-ion batteries offer an attractive alternative to other similar technologies that utilize sodium-based chemistries (such as sodium-sulphur batteries) as they can operate at room-temperature, much like lithium-ion batteries (sodium-sulphur batteries, for example, operate only at high temperatures).
However, compared to their lithium-ion counterparts, sodium-ion batteries actually have lower energy densities. This makes them less attractive for the electric car market (larger batteries would be needed for the same power output), however, the additional weight may not be an issue for stationary applications such as grid/electricity storage.
But more importantly, sodium is cheaper than lithium, potentially making sodium-ion batteries less expensive than their lithium counterparts. Being far more naturally abundant than lithium, sodium is also less susceptible to extreme price fluctuations as the battery market expands.
As another sodium battery researcher from Argonne National Laboratory, Christopher Johnson explains, “The big concerns for stationary energy storage are cost, performance and safety, and sodium-ion batteries would theoretically perform well on all of those measures.”
Will sodium-ion batteries be worth their salt in the emerging battery storage competition? With plans to further improve on and commercialise the new anode technology, Dr. Singh certainly hopes so.
Top Image Credit: Gurpreet Singh via IEEE Spectrum
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