Silver-coated PBO yams

Copper-coated PBO yams were obtained from the AmberStrand company [24]. They are made from a number of very thin copper-coated PBO filaments, bunched together to form a filament yam (about 10 pm diameter). Silver-coated PBO yams were also obtained from AmberStrand company [24]. They are similar to the copper-coated PBO filaments except that they use silver metal to clad the PBO filaments. Stainless steel filament yam electrodes were obtained from the Bekintex company [25]. The conductive yams were of different sized constmction and diameters, and a standard measurement was performed to determine the resistance per meter of each conductive yam. The material specifications of these conductive yams are presented in Table 20.1. 

Type of yarn electrode Copper-coated PBO yam Silver-coated PBO yam Stainless steel yarn... 

For the yarn electrodes three types of conductive yams were used copper-coated PBO filament yarn electrodes, silver-coated PBO filament yams from AmberStrand company [24], and pure stainless steel filament yam from Bekintex company [25]. The yarn electrodes separation distance within the active region of the device was... 

The voltage decay curves for the stainless steel filament yam electrodes remained at a constant voltage of 0.4 V for quite a long time compared to the silver-coated PBO filament yam electrodes whose decay tends to remain constant at 0.2 V. These devices can be used for voltage stabilization for 1 h if the load resistor is not too small. 

Figure 20.7 Voltage decay behavior for a device made of silver-coated PBO filament yam electrodes at various charging times.

The difference in performance between stainless steel filament yam electrodes and silver-coated PBO filament yam electrodes could be explained by the electrolytic phenomena observed by Bhattacharya [12] in their devices with silver-coated yam electrodes in the electron microscope measurement, they clearly observed migration of silver particles with the silver-coated yam electrodes. PEDOT PSS acted as an electrolyte that silver could migrate through in the presence of an electric field. There was also a possibility of chemical interaction at the silver/PEDOT PSS interface. However, with the stainless steel filament yam electrode, it is not clear if the electrolytic phenomenon exists in the first place, but this opens up the complexity in the mechanism of charge storage in these fabricated devices. Nevertheless we realized that the stainless steel filament yams had better performance in the fabricated cells. 

Textile-based energy storage devices were fabricated with PEDOTiPSS as the electrolyte, conductive yams as yam electrodes, and textile substrate. Copper-coated PBO filament yams, silver-coated PBO filament yarns, and pure stainless steel filament yams were used as yam electrodes to produce different types of devices. These charge storage devices were well integrated into textile stmcture, making them lightweight and flexible. The devices could be easily fabricated. 

A similar conclusion of good performance of pure stainless steel filament yam textile electrodes has also been reported in medical applications [27]. Additionally, the pure stainless steel filament yam electrodes are more robust and could withstand many cyclings of charge and discharge compared to the silver-coated yarn electrodes. The sUver-coated PBO filament yam electrode devices yielded before the stainless steel filament yam electrode devices. 

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