Researchers develop energy-dense sugar battery

Jan 21, 2014
Y.H. Percival Zhang (right), an associate professor of biological systems engineering at Virginia Tech, and Zhiguang Zhu show off their new sugar battery. Credit: Virginia Tech College of Agriculture and Life Sciences

A Virginia Tech research team has developed a battery that runs on sugar and has an unmatched energy density, a development that could replace conventional batteries with ones that are cheaper, refillable, and biodegradable.

The findings from Y.H. Percival Zhang, an associate professor of biological systems engineering in the College of Agriculture and Life Sciences and the College of Engineering, were published today in the journal Nature Communications.

While other sugar batteries have been developed, this one has an an order of magnitude higher than others, allowing it to run longer before needing to be refueled, Zhang said.

In as soon as three years, Zhang's new battery could be running some of the cell phones, tablets, video games, and the myriad other electronic gadgets that require power in our energy-hungry world, Zhang said.

"Sugar is a perfect compound in nature," Zhang said. "So it's only logical that we try to harness this natural power in an environmentally friendly way to produce a battery."

In America alone, billions of toxic batteries are thrown away every year, posing a threat to both the environment and human health, according to the Environmental Protection Agency. Zhang's development could help keep hundreds of thousands of tons of batteries from ending up in landfills.

This is one of Zhang's many successes in the last year that utilize a series of enzymes mixed together in combinations not found in nature. He has published articles on creating edible starch from non-food plants and developed a new way to extract hydrogen in an economical and environmentally friendly way that can be used to power vehicles.

In this newest development, Zhang and his colleagues constructed a non-natural synthetic enzymatic pathway that strip all charge potentials from the sugar to generate electricity in an enzymatic . Then, low-cost biocatalyst enzymes are used as catalyst instead of costly platinum, which is typically used in conventional batteries.

Like all fuel cells, the sugar battery combines fuel - in this case, maltodextrin, a polysaccharide made from partial hydrolysis of starch - with air to generate electricity and water as the main byproducts.

"We are releasing all electron charges stored in the sugar solution slowly step-by-step by using an enzyme cascade," Zhang said.

Different from hydrogen fuel cells and direct methanol fuel cells, the fuel sugar solution is neither explosive nor flammable and has a higher energy storage density. The enzymes and fuels used to build the device are biodegradable.

The battery is also refillable and can be added to it much like filling a printer cartridge with ink.

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Tony88
5 / 5 (1) Jan 21, 2014
IWBIWISI
Kedas
5 / 5 (3) Jan 21, 2014
No numbers.... but would be nice having a 'green' battery.
tekram
4.4 / 5 (7) Jan 21, 2014
This enzymatic fuel cell is based on non-immobilized enzymes that exhibit a maximum power output of 0.8 mW cm−2 and a maximum current density of 6 mA cm−2, which are far higher than the values for systems based on immobilized enzymes. Enzymatic fuel cells containing a 15% (wt/v) maltodextrin solution have an energy-storage density of 596 Ah kg−1, which is one order of magnitude higher than that of lithium-ion batteries. Sugar-powered biobatteries could serve as next-generation green power sources, particularly for portable electronics.
wellfeded
5 / 5 (6) Jan 21, 2014
SWEEEET!
DonGateley
5 / 5 (1) Jan 22, 2014
3 yrs away isn't bad as these things go. Revolutionary for held and worn electronics if the geometry needed to yield useful voltages is achieved. The numbers tekram gives imply a very low cell voltage on the order of 133 mV.
alfie_null
5 / 5 (2) Jan 22, 2014
Maybe a silly question, but would fuel cells like this be potentially subject to biological contamination? There are lots of critters that like to feed off sugar. Some sort of yeast or other fungus, for instance?
travisr
5 / 5 (2) Jan 22, 2014
We just need one that works off of glucose. Then we can mainline our phones and lose weight at the same time!

I've been talking all day, I need some donuts!!
Eikka
1 / 5 (2) Jan 22, 2014
have an energy-storage density of 596 Ah kg−1


That's not an energy storage density. That's charge storage density. Ampere-hours are basically Coulombs measured in a different way.

The numbers tekram gives imply a very low cell voltage on the order of 133 mV.


Adjusted for the 133 mV voltage, the implied energy density is just 79 Wh/kg which is three times worse than ordinary lithium batteries!

Of course the maximum current of the cell doesn't coincide with the maximum power, because the maximum current would be the cell's short-circuit current where the output voltage is zero, so the cell voltage cannot be directly calculated from the values given.
Eikka
1 / 5 (1) Jan 22, 2014
However, for an ideal battery, we know that the maximum power output occurs when the internal resistance is equivalent to the load resistance, and the open cell voltage of the battery is twice the load voltage at that point, and adding a load resistance equal to the internal resistance of the battery halves the output current from its maximum.

So for a single square centimeter cell, we got 0.8 mW going out at a load current of 3 mA which implies that the voltage at the load is just 0.27 mV and the open cell voltage, or maximum voltage of the cell would therefore be 0.53 mV

And with that sort of voltage, even if you do have 596 Ah of capacity per kg of solution, your energy density is just 0.317 Wh/kg or a thousand times worse than a regular lithium battery. It can push a whole lot of electrons around, but since it generates almost no voltage, it gives almost no net energy out.

Eikka
1 / 5 (1) Jan 22, 2014
15% (wt/v) maltodextrin solution


That is also incorrect, since the mass concentration is not a percentage but grams per volume. That's a common mistake.

But that aside, the energy contents of 15 grams of plain table sugar is about 236 kJ or 65 Wh. If that is dissolved in a kilogram of solution, the energy density would be 65 Wh/kg or four times worse than a regular lithium battery.

So the energy density of the battery cannot be ten times higher than lithium batteries because that would imply that maltodextrin is some sort of super-sugar that contains 40 times the energy of regular sugar, which it isn't.

So all these numbers given don't make sense. Either the numbers are wrong, or the great invention of the article is really just a hoax and exaggeration.
jalmy
1 / 5 (1) Jan 22, 2014
Why are you fools comparing this to Li-ion??????v I don't see where the article says these have higher energy density than li-ion. What it says is that it has an order of magnitude energy density greater than previous sugar batteries. The benefit in this battery has nothing to do with energy density. It is in the fact that you can recharge it by injecting some f'ing sugar water. You people are stupid. READING COMPREHENSION IS HARD.
Eikka
not rated yet Jan 22, 2014
Why are you fools comparing this to Li-ion??????v I don't see where the article says these have higher energy density than li-ion.


I'm pretty sure it did. They seem to have edited it discreetly.

It also says:

Different from hydrogen fuel cells and direct methanol fuel cells, the fuel sugar solution is neither explosive nor flammable and has a higher energy storage density.


If the numbers given here are correct, it simpy doesn't.
DonGateley
not rated yet Jan 22, 2014
They need to get _much_ more specific with their claims. Smoke is appearing in my mirror.
Nestle
5 / 5 (1) Jan 22, 2014
the energy density would be 65 Wh/kg or four times worse than a regular lithium battery.
Fats and ethanol have energy density 37 and 29 kJ/g (8.8 and 6.9 kcal/g), respectively. Proteins and most carbohydrates have about 17 kJ/g (4.1 kcal/g). Polyols (including sugar alcohols) and organic acids contribute 10 kJ/g (2.4 kcal/g) and 13 kJ/g (3.1 kcal/g) respectively. The lithium ion batteries (0.36 – 0.875 kJ/g) are expensive, sensitive to air and humidity, they've tendency for self-ignition. The lithium element is expensive and difficult to recycle. Recently another important progress has been made in utilization of sugars has been made with using of valerolactone for non-ezymatic production of sugar from biomass. If we would succeed with non-enzymatic sugar batteries, it would be great, because enzymatic batteries work at narrow range of temperatures only.
DonGateley
not rated yet Jan 22, 2014
@Nestle: If I read you correctly, Polyols (which I am guessing is the basis for this announcement) have a specific energy advantage of 11.4 - 27.8 over Lithium. Is that correct?
Nestle
5 / 5 (1) Jan 22, 2014
Yes. But for example non-rechargable lithium battery have an energy density 1.8 kJ/g and pure lithium-air battery (which aren't produced yet at commercial basis) could have theoretical energy density 18.7 kJ/g - so there is still lotta space for improvement.
DonGateley
not rated yet Jan 22, 2014
@Nestle again:

So to which type, enzymatic or non-enzymatic, does this announcement pertain? There was non-something mentioned in it but I don't know what that meant. If narrow temperature regulation is required that surely dampens my enthusiasm.
Whydening Gyre
not rated yet Jan 22, 2014
@Nestle again:

So to which type, enzymatic or non-enzymatic, does this announcement pertain? There was non-something mentioned in it but I don't know what that meant. If narrow temperature regulation is required that surely dampens my enthusiasm.

Don,
They do make reference to enzymatic."We are releasing all electron charges stored in the sugar solution slowly step-by-step by using an enzyme cascade," Zhang said.
Yes it's workable, but limited by the afore-mentioned temp. boundary (not mentioned).

Non-enzymatic is definitely a preferred way to go. However, as in all progress, time and more work will be required. No worries, tho - stay enthused!
Eikka
not rated yet Jan 23, 2014
@Nestle: If I read you correctly, Polyols (which I am guessing is the basis for this announcement) have a specific energy advantage of 11.4 - 27.8 over Lithium. Is that correct?


In their raw form perhaps, but you have to mind that you need to put them into solution before they can actually be used in a fuel cell.

Raw maltodextrin for example is rather dry stuff, resembling corn starch, and in very strong solutions it actually becomes a glue that was used in times past to hang up wallpaper, or assemble scrapbooks, or to make plywood etc. You can only mix so much into water before it becomes impossible to pump or flow within small cavities, which limits the practical energy density.

Urgelt
not rated yet Jan 27, 2014
It's not a battery - since it can't be charged electrically. It's a fuel cell. The article confuses the two terms rather badly.

The article is also terribly vague as to its assertion that the sugar-based fuel cell has a higher energy density. Higher than what, exactly, and by how much?
jalmy
1 / 5 (3) Feb 11, 2014
It's not a battery - since it can't be charged electrically. It's a fuel cell. The article confuses the two terms rather badly.

The article is also terribly vague as to its assertion that the sugar-based fuel cell has a higher energy density. Higher than what, exactly, and by how much?


Again you people cannot read. First of all there is nothing in the definition of the word "battery" that says it has to be charged electrically. It is in fact a battery. It gets recharged by sugar water. It has higher energy density than previous sugar water batteries by a great amount. This is all you need to know. Now f-off try reading dick and jane books, they maybe your reading comprehension level.
Urgelt
5 / 5 (2) Feb 11, 2014
"Try reading dick and jane books, they maybe your reading comprehension level."

Doesn't seem to be working for you, jalmy. Goodness, but that's a clumsy sentence.

I stand by my posted comment. The device described in the article is a fuel cell. Fuel cells really are different from electrical batteries - though some of the same physics are involved, the key point is that they are charged - and recharged - by adding fuel.
Thnder
not rated yet Feb 20, 2014
"A Virginia Tech research team has developed a battery that runs on sugar and has an unmatched energy density, a development that could replace conventional batteries with ones that are cheaper, refillable, and biodegradable."

Perhaps jalmy should practice what they preach, starting with the opening sentence of the article.

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