FWIU, Heat-treated hemp bast fiber is comparable to graphene electrodes, and at least was far less costly because bast fiber is otherwise a waste output (and graphene at least was hazardous to produce and doesn't have a natural dendritic branch structure).
> 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.
>> Here's a discussion about the lower costs of hemp supercapacitors as compared with graphene super capacitors: https://news.ycombinator.com/item?id=16814022
FWIU, Heat-treated hemp bast fiber is comparable to graphene electrodes, and at least was far less costly because bast fiber is otherwise a waste output (and graphene at least was hazardous to produce and doesn't have a natural dendritic branch structure).
"Hemp Carbon Makes Supercapacitors Superfast" (2013) https://www.asme.org/engineering-topics/articles/energy/hemp... :
> 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.