04-06-2012, 02:02 PM
Stretchable, Porous, and Conductive Energy Textiles
Stretchable, Porous, and Conductive Energy.pdf (Size: 550.48 KB / Downloads: 44)
Wearable electronics represent a developing new
class of materials with an array of novel functionalities,
such as flexibility, stretchability, and
lightweight, which allow for many applications and designs
previously impossible with traditional electronics technology.
High-performance sportswear, wearable displays, new
classes of portable power, and embedded health monitoring
devices are some examples of these novel applications.1-3
All these electronic applications require lightweight, wearable
power conversion and storage devices. Textile is a flexible and
porous material made by weaving or pressing natural or
synthetic fibers, such as cotton or polyester. The ideal wearable
power would incorporate textile as a component. Previously,
studies have been done for integrating nanoscale materials into
textiles to improve the clothing colors, antiodor function, UV
protection, and human biomonitoring.4-6 In this work, we
conformally coat single-walled carbon nanotubes (SWNTs)
on cellulose and polyester fibers to make porous conductors.
The fabrication process is simple and scalable, similar to
those widely used for dyeing fibers and fabrics in the textile
industry. The SWNT coating makes these textiles highly
conductive with sheet resistance less than 1Ω/sq. The
conductive textiles (e-Textile) show outstanding mechanical
and chemical properties.
Porous Textile Conductor for Energy Storage.
Porous textile conductor with SWNT coating was tested as both
active charge storage electrodes and current collectors in
SCs. Figure 3a shows the schematic drawing of the SC tested,
where 1 M LiPF6 electrolyte is used. The porous structure of
conductive cotton facilitates the access of electrolyte to SC
FIGURE 2. Properties of textile conductors. (a) Sheet resistance of fabric and cotton sheet after SWNT coating, which shows the same values
on both faces for either fabric or cotton. The sheet resistances decrease by a factor of approximately 3 after HNO3 treatment. (b) Excellent
mechanical properties of conductive textile, that is, strong adhesion between SWNTs and textile (passing the scotch tape test), foldable, and
stretchable. © The SWNT-coated textiles show unusual stretching properties. The film sheet resistance decreases as the SWNT/fabric is stretched
up to 240% of its initial length, after which the resistance starts to increase. (d) SWNT/cotton is resistant to water washing, thermal treatment
electrode materials, that is, SWNTs. We tested the SC
performance under galvanostatic cycling with a variety of
currents (Figure 3b). The linear voltage-time profile confirms
the charging and discharging of the SCs.