A yarn-based sweat-activated battery constructed with conjugated electrospun nanofiber separators as a durable and high-capacity power source in textile electronics

The one-dimensional yarn-based sweat-activated battery (y-SAB) has been considered a promising power source for textile electronics due to its high flexibility, stable output, and compatibility with conventional weaving/knitting techniques. However, its practical applications are hampered by its relatively low energy capacity, especially at higher current densities, and the loose binding of the fiber-based separating layer. Here, a core-sheath y-SAB fabricated using an electrospun polyacrylonitrile (PAN) nanofiber separator was developed through a conjugated electrospinning technique. This innovative y-SAB design not only achieves a reduced diameter with the tight covering of PAN nanofiber film but also demonstrates almost doubled capacity (28.5 mAh) compared to its counterpart with a cotton yarn separator (15.8 mAh) in artificial sweat. It also delivers higher capacity in harsh electrolytes like 1 M NaCl and 1 M KOH. The remarkable improvement can be attributed to the tight and dense wrapping of the PAN nanofibers around the zinc electrode, which inhibits localized corrosion of the zinc wire and prevents the contamination of the cathode surface by corrosion products such as zinc oxide and simónkolleite. The proposed y-SAB could tolerate 13,000 cycles of bending and 3200 cycles of twisting without significantly reducing its performance, allowing it to be woven into textiles for powering wearable electronic devices. This study introduces an innovative approach for fabricating high-efficacy yarn batteries designed for integration with machine weaving technologies and also provides some insights into the inhibition of localized zinc corrosion in SABs.