January 28, 2013 | 5
A new world record is in the books for battery technology. Thanks to a tiny particle resembling an egg yolk and shell, scientists have been able to dramatically increase lithium-ion battery storage capacity.
According to their paper in Nature Communications (published January 8*), researchers from Stanford University and the SLAC National Accelerator Laboratory a new material described as a “sulfur-TiO2 yolk-shell nanoarchitecture with internal void space for long-cycle lithium-sulphur batteries.” This material can be used in the cathode of lithium-ion batteries to overcome a key obstacle that has stumped scientists for the past two decades.
This result – a fivefold increase in the amount of energy that can be stored in the battery (per unit of sulfur) plus a long life material that could revolutionize the rechargeable battery market.
According to Stanford’s Yi Cui, a researcher on the project that developed this material:
“After 1,000 charge/discharge cycles, our yolk-shell sulfur cathode had retained about 70 percent of its energy-storage capacity. This is the highest performing sulfur cathode in the world, as far as we know…Even without optimizing the design, this cathode cycle life is already on par with commercial performance. This is a very important achievement for the future of rechargeable batteries.”
Battery researchers have long known that sulfur could help to increase the storage capabilities of lithium-ion batteries. But, the combination of sulfur and lithium ions was problematic. In particular, how to allow the cathode to operate without the material simply dissolving with each charge.
This new nanoparticle’s structure prevents this problem by providing space between the sulfur (the egg-yolk) and its hard shell (a porous titanium oxide). This allows the combined sulfur-lithium compound to expand without cracking or dissolving. This structure is shown in the pictures below:
*Note: Scientific American is part of Nature Publishing Group
H/T to IEEE Spectrum’s Dexter Johnson.