New Scientist: Two carbon-fiber wires, coated with standard black pen ink, are the heart of a supercapacitor created by researchers from Peking University in Beijing, China. Wrapped in a flexible plastic sheath that is then filled with an electrolytic fluid, the new device outperforms other carbon-fiber-based supercapacitors and can hold up to 10 times the charge. The researchers had previously discovered that the pen ink contains carbon nanoparticles, which makes it an excellent charge-storing material. And 1 g of the ink can cover a surface area of 27 m2. Supercapacitors are used for storing large amounts of electrical energy, and they can release that energy very quickly. The researchers believe that their flexible device will be useful for wearable electronics.