Batteries, by definition, convert chemical energy into electricity. Once you’ve sucked them dry, you have to reverse the process to convert electricity into chemical energy, and for that, you need a source of electricity. It’s not like it’s hard to do this, but it is certainly a minor annoyance that could do with a fix.
Under artificial light, this prototype battery has a capacity of 77.8 mAh/g. It’ll quite happily power a small fan or LED light for about 30 seconds, and then if you give it a break for 30 seconds while shining a light on it, it’ll be all charged up and good to go again. Over 100 cycles, the battery retained a bit over 70 percent of its discharge capacity, which at least suggests some potential for longevity and usefulness.
In addition to being charged directly by light, which is pretty awesome, this battery design offers other benefits, including “
a sustainable and economical anode material which will not be consumed as a part of the discharge reactions, and
an anode material that is free from loss of active materials, irreversible structural deformations, spontaneous deinsertion reactions, and safety concerns commonly encountered in the state of the art anode materials in [aqueous rechargeable batteries].”
Here we show a surrogate strategy for power production, wherein light is
used to actuate a discharge chemistry in the cathode of an aqueous
rechargeable battery (ARB). The proposed photo battery consists of a
titanium nitride photoanode, promising cathode material iron(III)
hexacyanoferrate(II) as the battery active species and Na2S2O8
as the chemical charging agent. The photo battery delivered negligible
capacity in the dark and the capacity shot up to 77.8 mAh/g when
artificially shined light, confirming that the battery chemistry is
light driven. In the ambient light, the device retained 72% of its
artificial light discharge capacity with a stable cycling for more than
100 cycles. Further, an unprecedented means for charging the battery
rapidly is presented using Na2S2O8 and
it revitalized the battery in 30 s without any external bias. This
methodology of expending a photoanode extends to a battery that is free
from dissolution of active materials, irreversible structural changes,
spontaneous deinsertion reactions, and safety concerns commonly
encountered in the state of the art anode materials in ARBs. Apart from
bringing out a sustainable way for power production, this device opens
up avenues for charging the battery in the likely events of electrical
input unavailability, while solving the critcial issues of longer
charging time and higher charging voltage. Source: http://pubs.acs.org/doi/full/10.1021/acs.jpcc.5b02871.
According to a press release from the American Chemical Society, “the researchers say their design is a promising first step toward a more sustainable and safer battery technology.” In other words, this is a thing that does cool stuff in a lab right now, but getting your hopes up for a light-powered battery in your cell phone might be premature by a decade or so. For now, the best you’ll be able to do is read the full paper here.
ORIGINAL:IEEE Spectrum
By Evan Ackerman
Posted 24 Jun 2015
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