We tend to think of batteries as being inanimate objects, even though they expand, contract and flex their electric muscles within their cylindrical or pouch forms as they charge and discharge. This type of internal wiggling helps reduce and finally destroy the battery’s ability to make our remotes change channels or keep our airplanes flying. Researchers at the Beijing Institute of Technology have found a way to use the product of much internal and external wiggling, natural silk that is “biomass-derived” and processed to form carbon-based nanosheets that might be used in lithium-ion batteries and other energy storage devices. The American Chemical Society reports that Chuanbao Cao and his researchers worked with the idea that carbon is a key component in commercial Li-ion energy storage devices including batteries and supercapacitors. They wanted to find a natural and sustainable alternative to graphite, which has limited specific energy and eventually granulates into a fine powder, causing the battery to fail. Cao and …
Lithium-Sulfur Cells Wrapped in Graphene
Graphene is science fiction made real – a one-atom thick layer of hexagonal arrays of carbon which weigh next to nothing and are stronger than any other material on earth. Wrap a layer of this stuff around “a novel multifunctional sulfur electrode that combines an energy storage unit and electron/ion transfer networks,” and you get “an extremely promising electrode structure design for rechargeable lithium-sulfur batteries.” Lithium-sulfur batteries have the promise of reaching a theoretical specific energy density “approaching 2,600 Watt-hours per kilogram (Wh kg-1),” compared to currently available specific energy densities for lithium-ion cells of 130-220 Wh kg-1. Researchers led by Dr. Vasant Kumar at the University of Cambridge and Professor Renjie Chen at the Beijing Institute of Technology worked to overcome the shortcomings of lithium-sulfur batteries now under development – a “fading” of the sulfur through a series of reactions with the anode, electrolyte, and lithium cathode, a kind of “shuttling” between these battery components, and the small number …