Everyone loves a good sandwich and in the near future, so might your cellphone… While you may enjoy turkey sandwiches, your cellphone may prefer silicon carbon nitride-wrapped molybdenum disulfide (MoS2) sheets.
Described as tiny “sandwiches,” these sheets show improved stability as a battery electrode with little capacity degradation over time.
MoS2 sheets store more than twice as much lithium than bulk molybdenum disulfide reported in previous studies.
Early findings using only MoS2 revealed that despite the sheet’s high lithium capacity, the material couldn’t hold the charge, dropping after just five charging cycles.
"This kind of behavior is similar to a lithium-sulfur type of battery, which uses sulfur as one of its electrodes," says Gurpreet Singh, assistant professor of mechanical and nuclear engineering with Kansas State University.
"Sulfur is notoriously famous for forming intermediate polysulfides that dissolve in the organic electrolyte of the battery, which leads to capacity fading. We believe that the capacity drop observed in molybdenum disulfide sheets is also due to loss of sulfur into the electrolyte."
To address this problem, Singh’s team wrapped the MoS2 sheets with layers of silicon carbon nitride (SiCN). This resulted in stable cycling of the lithium-ions, both on copper foil and self-supporting flexible paper used in bendable batteries.
SiCN was also found to protect against mechanical and chemical degradation with liquid organic electrolyte.
Singh and team are now hoping to discover how MoS2 will react in devices that undergo a large number of charging cycles, like cellphones.
The team’s findings first appeared in Nature’s Scientific Reports in the article “Polymer-Derived Ceramic Functionalized MoS2Composite Paper as a Stable Lithium-Ion Battery Electrode.”
The applications of this discovery go beyond just cellphones of course. Laptops, cameras and a list of portable electronic devices can benefit from the improved battery life SiCN-wrapped MoS2 sheets can offer. But what about vehicle engine batteries?