31-10-2012, 03:43 PM
Paper battery may power electronics in clothing and packaging material
[attachment=37600]
ABSTRACT
Albert Mihranyan and colleagues note in the report that scientists are trying to develop light, ecofriendly,
inexpensive batteries consisting entirely of nonmetal parts. The most promising materials include so-called
conductive polymers or "plastic electronics."
One conductive polymer, polypyrrole (PPy), shows promise, but was often regarded as too inefficient for
commercial batteries. The scientists realized, however, that by coating PPy on a large surface area substrate
and carefully tailoring the thickness of the PPy coating, both the charging capacity and the charging
(discharging) rates can be drastically improved.
The secret behind the performance of this battery is the presence of the homogeneous, uninterrupted,
nano-thin coating — about 1/50,000th the thickness of a human hair — of PPy on individual cellulose
fibers which in turn can be molded into paper sheets of exceptionally high internal porosity. It was special
cellulose, extracted from a certain species of green algae, with 100 times the surface area of cellulose found
in paper. That surface area was key to allowing the new device to hold and discharge electricity very
efficiently.
The innovative design of the battery cell was surprisingly simple yet very elegant since both of the
electrodes consist of identical pieces of the composite paper separated by an ordinary filter paper soaked
with sodium chloride serving as the electrolyte. The potential difference is solely due to differences
between the oxidized and reduced forms of the functional PPy layer. The battery recharged faster than
conventional rechargeable batteries and appears well-suited for applications involving flexible electronics,
such as clothing and packaging, the scientists say. Alternatively, low-cost very large energy storage devices
having electrodes of several square yards in size could potentially be made in the future.
[attachment=37600]
ABSTRACT
Albert Mihranyan and colleagues note in the report that scientists are trying to develop light, ecofriendly,
inexpensive batteries consisting entirely of nonmetal parts. The most promising materials include so-called
conductive polymers or "plastic electronics."
One conductive polymer, polypyrrole (PPy), shows promise, but was often regarded as too inefficient for
commercial batteries. The scientists realized, however, that by coating PPy on a large surface area substrate
and carefully tailoring the thickness of the PPy coating, both the charging capacity and the charging
(discharging) rates can be drastically improved.
The secret behind the performance of this battery is the presence of the homogeneous, uninterrupted,
nano-thin coating — about 1/50,000th the thickness of a human hair — of PPy on individual cellulose
fibers which in turn can be molded into paper sheets of exceptionally high internal porosity. It was special
cellulose, extracted from a certain species of green algae, with 100 times the surface area of cellulose found
in paper. That surface area was key to allowing the new device to hold and discharge electricity very
efficiently.
The innovative design of the battery cell was surprisingly simple yet very elegant since both of the
electrodes consist of identical pieces of the composite paper separated by an ordinary filter paper soaked
with sodium chloride serving as the electrolyte. The potential difference is solely due to differences
between the oxidized and reduced forms of the functional PPy layer. The battery recharged faster than
conventional rechargeable batteries and appears well-suited for applications involving flexible electronics,
such as clothing and packaging, the scientists say. Alternatively, low-cost very large energy storage devices
having electrodes of several square yards in size could potentially be made in the future.