Researchers at the Polytechnic School of Montreal in Canada have built a battery that can be woven into a garment. According to the researchers, generally speaking, textiles are defined as "smart" if they can respond to the environmental stimulus, such as mechanical, thermal, chemical, electrical, and magnetic. Many applications of "smart" textiles stem from the combination of textiles and electronics (e-textiles).Most of the "smart" functionalities in the early prototypes of e-textiles were enabled by integrating conventional rigid electronic devices into a textile matrix. The incompatibility of the rigid electronic components and a soft textile matrix create a significant barrier for spreading of this technology into wearables.
To drive electronics in a smart textile requires an efficient, lightweight and flexible battery source. Ideally, such a source will be directly in the form of a fiber that can be naturally integrated into smart textile during weaving.
To build their battery they sandwich a solid polyethylene oxide electrolyte between a lithium iron phosphate cathode and lithium titanate anode. All of these are thermoplastic materials, which can be stretched under mild heating. After stretching, battery films were cut into 1 cm-wide ∼10 cm long strips which were integrated into a textile during weaving with a manual Dobby loom. Cotton threads were holding the battery attached on the surface of a textile, while conductive threads were used to weave textile electrodes and to connect the individual battery strips in series. "It's the first fully wearable, soft lithium-ion battery that uses no liquid electrolytes," claims Maksim Skorobogatiy who lead the research.
Top row: photographs of a flexible battery made of binding individual cathode, anode and polymer electrolyte films. Middle row: resulting battery is highly stretchable. Bottom row: battery stripes (black) woven into a textile (blue and red cotton threads) using Dobby loom. The stripes are connected in series with conductive threads (metallic brown). Two textile electrodes are formed by the conductive threads at the textile extremities.
Skorobogatiy claims that clothing made using this material could provide hundreds of volts for use in emergency situations such as powering distress signals. The next step for the teams is to make the fabric washable and waterproof.
Source and images: Polytechnic School of Montreal
Top image: Maksim Skorobogatiy