Powering Phones, PCs Using Sugar

Nerval's Lobster writes "A team of researchers at Virginia Tech University have developed a battery with energy density an order of magnitude higher than lithium-ion batteries, while being almost endlessly rechargeable and biodegradable as well – because it's made of sugar. The battery is an enzymatic biofuel fuel cell – a type of fuel cell that uses a catalyst to strip molecules from molecules of a fuel material. Instead of using platinum or nickel for catalysts, however, biofuel cells use the catalysts made from enzymes similar to those used to break down and digest food in the body. Sugar is a good fuel material because it is energy dense, easy to obtain and transport, and so simple to biodegrade that almost anything biological can eat it. Sugar-based fuel cells aren't new, but existing designs use only a small number of enzymes that don't oxidize the sugar completely, meaning the resulting battery can hold only small amounts of energy that it releases slowly. A new design that uses 13 enzymes that can circulate freely to get better access to sugar molecules, however, is able to store energy at a density of 596 amp-hours per kilogram – an order of magnitude higher than lithium-ion batteries, according to Y.H. Percival Zhang, who studies biological systems engineering at the College of Agriculture and Life Sciences and College of Engineering at Virginia Tech. "Sugar is a perfect energy storage compound in nature," Zhang said in a statement announcing publication in Nature Communications of his paper describing the battery. "So it's only logical that we try to harness this natural power in an environmentally friendly way to produce a battery.""

The power density is terrible (sigh)

[cryptoengineer2]

The linked abstract indicates around 0.25 mW/cm^2 (electron exchange membrane area). I'm not in any way a fuel cell expert, but that seems kind of low. Other fuel cells get from 0.2 to 2 Watts (not mW) /cm^2. Sure, sugar has a high energy density, and this project uses it efficiently. But the batteries would be huge, to get reasonable power.

It's not a battery.

[Areyoukiddingme]

It's not a battery. It's a fuel cell. The reaction is not internally reversible. Once all the accessible sugar has been oxidized, you need new sugar to refuel it. It doesn't recharge. Most likely you wouldn't bother to refuel it at all. You'd treat it as a disposable that you simply replace, like an alkaline cell. The quoted 596 Ah/kg compares very favorably to the 92 Ah/kg of an alkaline. Of course, that's comparing a theoretical charge density calculated from lab equipment to a product. By the time you squeeze the lab equipment into the AA or AAA form factor, you can expect that quoted 596 to suffer rather badly.

Re:Amp hours per kilogram

[Firethorn]

I'm not sure where your thinking process is broken, but I'll give it a try.

Amp-hours isn't a statement of energy. For example, you could have 2 '5 amp-hour' batteries, but because one is 12V and the other 6V, the amount of energy each contains is very different, with the 12V one being able to supply twice as much energy before becoming exhausted. Because this is a new battery technology, we don't know what the voltage of the battery is.

Watts are a statement of power, Joules are a statement of energy, or power over time. Amps are mostly a statement of volume of electron flow. Without knowing the force behind them(voltage), you can't say how much work you can do with them.

Re:Technology should be used asap

[DMUTPeregrine]

This is a fuel cell, not a battery. It can't be recharged without refueling it. The enzymes are probably what breaks down, so you'd need to put more in. Since they break down rapidly (as most enzymes do) that means making them locally. You can't just plug these into the wall to recharge them, you have to empty and refuel them.

Re:Amp hours per kilogram

[sandertje]

If you would simply read the damn abstract (no money needed for that) it already states the following: a maximum power output of 0.8mW/cm^2 and a maximum current density of 6mA/cm^2. Now you have Power (in W) and Amperage (in A). Simply divide to get Voltage (V).

Re:Amp hours per kilogram

[sjames]

That's still quite a problem when the cell voltage is 0.13 (remember, the cm^2 terms cancel). You'd need to stack 28 cells to get to the nominal LiIon voltage.

Converting the impressive sounding 590 Ah/kg to to the more useful Wh/kg, we get a much less impressive sounding 76 Wh/kg. LiIon is 100-250 Wh/kg depending on exact formulation.