Hemp Carbon Makes Supercapacitors Superfast

tl;dr hemp can be heat dried/decayed in to a form of carbon nanowires.

Professor David Mitlin, developed a process for converting fibrous hemp waste into a unique graphene-like nanomaterial that outperforms graphene. What’s more, it can be manufactured for less than $500 per ton.

Hemp fiber waste was pressure-cooked (hydrothermal synthesis) at 180 °C for 24 hours. The resulting carbonized material was treated with potassium hydroxide and then heated to temperatures as high as 800 °C, resulting in the formation of uniquely structured nanosheets. Testing of this material revealed that it discharged 49 kW of power per kg of material—nearly triple what standard commercial electrodes supply, 17 kW/kg.

Moreover, adds Mitlin, the assembled supercapacitor device yielded a maximum energy density of 12 Wh kg-1—significantly higher than those for commercially available supercapacitors. By taking advantage of the complex multilayered structure of a hemp bast fiber precursor, these high-performing carbons were created by simple hydrothermal carbonization combined with activation.