Robert Murray-Smith makes lots of different batteries so if you are interested in batteries, exploring his videos is enlightening.
In this one, he makes a supercapacitor. It is hard to follow the audio as the sound is low, but hang in there. It starts with “chalk talk” then moves to the lab. He starts with using a zeolite as a super electrolyte, (clay paste) then moves to seaweed (think sushi nori from the Asian grocer), then ends with a home made emulsion of sugar, salt, water in oil with a drop of emulsifying agent. Dish soap in this case. But I can’t help thinking that sounds a lot like cake frosting…. mostly fat with some salty sugar water emulsified into it. Vanilla anyone? Or a bit of egg yolk as emulsifier.
This is spread thinly on electrodes. First aluminum foil for the seaweed, then a stainless steel mesh for the “frosting”. Starting near pf theoretical ranges, he ends at about 0.3 Farads at about 1 Volt.
I find myself wondering if a bit of tissue paper would standardize the thickness? He has videos about a “hemp battery” that looks rather like a hemp carbon mat supercapacitor, and searching on hemp battery finds a lot of hemp supercapacitor pages. He also has one where he wraps one plate of a lead acid cell in carbon mat and dramatically extends battery life cycles (from about 500 to near 15,000). For hemp, the bast layer under the bark, roasted for hours in a 350 F oven, makes a material about the same as graphene, or better, for making supercapacitor devices.
So perhaps a very thin hemp carbon layer smeared with emulsion between two plates?
This also has implications for biology, as our cells are oil and sugar/salt water devices. Makes a fella go Hmmmm.
He also made a kind of graphene ink (if I heard correctly) that may have been where he started. Here he shows the effect of coating an electrode with it. A 128,000 time improvement over a simple capacitor.
This is revisiting the strange capacitive behaviour of graphene ink as a possible solid state storage device – here we use PET and concentrate on the plate material that doesn’t exclude the exotic dielectric materials to get further performance increases from this device.
Are hemp batteries about to change the world?
According to Phys.org, fibres from hemp may have just as much energy storage capacity as graphene, an atom-thick material that can be made into electrodes. Graphene has been the favourite choice for use in supercapacitors.
Supercapacitors have the ability to charge up in a matter of seconds, unlike traditional rechargeable batteries that can take hours. They also have a large capacity for energy storeage than traditional batteries.
By heating the hemp fibres for 24 hours at 350 degrees Fahrenheit, scientists were able to produce carbon nanosheets, which was then used to build supercapacitors.
Fully assembled, the devices performed far better than commercial supercapacitors in both energy density and the range of temperatures over which they can work. The hemp-based devices yielded energy densities as high as 12 Watt-hours per kilogram, two to three times higher than commercial counterparts. They also operate over an impressive temperature range, from freezing to more than 200 degrees Fahrenheit.
Small-scale manufacturing of the hemp-based supercapacitors is due to begin soon.
Which points to a phys.org article.
His team found that if they heated the fibers for 24 hours at a little over 350 degrees Fahrenheit, and then blasted the resulting material with more intense heat, it would exfoliate into carbon nanosheets.
Mitlin’s team built their supercapacitors using the hemp-derived carbons as electrodes and an ionic liquid as the electrolyte. Fully assembled, the devices performed far better than commercial supercapacitors in both energy density and the range of temperatures over which they can work. The hemp-based devices yielded energy densities as high as 12 Watt-hours per kilogram, two to three times higher than commercial counterparts. They also operate over an impressive temperature range, from freezing to more than 200 degrees Fahrenheit.
“We’re past the proof-of-principle stage for the fully functional supercapacitor,” he says. “Now we’re gearing up for small-scale manufacturing.”
Though I’m sure there is a “some assembly required” issue…
Here’s the one where he shows how to upgrade a simple lead acid battery (and with much better sound):
An Ultrabattery is an Australian invention that is a mix of battery and supercapacitor designed to improve the qualities of lead acid batteries. They are stunningly easy to make and in this video I show you how. You can buy materials for your own experimenting from our webshop at www.workingink.co.uk.
I like his attitude about risks ;-)
So as someone thinking about DIY power storage, I find these advances very interesting. From a simple lead-acid upgrade for very extended cycle life, to ultracapacitors made from farm waste and “frosting”, it looks like the science is still not quite settled ;-)
Then the notion that plant black carbon ink can make supercapacitors is rather shocking, as we’ve had carbon black ink and metals for thousands of years. One wonders if the archeologists looking at the Bagdad Battery looked for a carbon black layer?