Bright Future for Energy Devices
https://www.mtu.edu/news/stories/2016/december/bright-future-for-energy-devices.html[font face=Serif][font size=5]Bright Future for Energy Devices[/font]
By Allison Mills | Published December 20, 2016
[font size=4]Scientists at Michigan Technological University invented a method to take a material out of theory and make it into a real electrode.[/font]
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High electrical conductivity and large accessible surface area, which are required for ideal electrode materials in energy devices, are opposed to each other in current materials. Amorphous carbon has low conductivity but large surface area. Graphite, on the other hand, has high conductivity but low surface area. Three-dimensional graphene has the best of both propertiesand the sodium-embedded carbon invented by Hu at Michigan Tech is even better.
In the dye-sensitized solar cell world, every tenth of a percent counts in making devices more efficient and commercially viable. In the study, the platinum-based solar cell reached a power conversion efficiency of 7.89 percent, which is considered standard. In comparison, the solar cell using Hu's sodium-embedded carbon reached efficiencies of 11.03 percent.
Supercapacitors can accept and deliver charges much faster than rechargeable batteries and are ideal for cars, trains, elevators and other heavy-duty equipment. The power of their electrical punch is measured in farads (F); the material's density, in grams (g), also matters.
Activated carbon is commonly used for supercapacitors; it packs a 71 F g-1 punch. Three-dimensional graphene has more power with a 112 F g-1 measurement. Sodium-embedded carbon knocks them both out of the ring with a 145 F g-1 measurement. Plus, after 5,000 charge/discharge cycles, the material retains a 96.4 percent capacity, which indicates electrode stability.
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http://pubs.acs.org/doi/abs/10.1021/acs.nanolett.6b04742