Strain-insensitive yarn supercapacitor based on conductive polypyrrole-bridged MOF nanoarrays

The crinkled active coating deforms with yarn substrates upon stretching, making electrodes strain-insensitive. • Polypyrrole (PPy) bridges adjacent Ni-CAT units to accelerate interfacial electron transfer and reduce contact resistance. • The interconnected porous channels in Ni-CAT facilitate fast ion migration and reduce diffusion resistance. • The yarn supercapacitor retains 90% capacitance under stretching, bending, and twisting, showing outstanding strain-insensitivity. Endowed with remarkable flexibility and weavability, yarn-based supercapacitors hold substantial promise as energy-storage devices for wearable electronic textiles. However, current supercapacitors lack stretchability and struggle to maintain structural integrity and electrochemical stability under the complex, multi-dimensional deformations caused by human movement, which severely limits their practical application in wearable electronics. This study prepared a strain-insensitive yarn supercapacitor with a crinkled structure using a pre-stretched interfacial polymerization method through structural design and material selection. The supercapacitor demonstrates a high area capacitance of 27.9 mF cm −2 (40.13 F g −1 ), a power density of 37.42 μW cm −2 (54.26 W kg −1 ) and an energy density of 2.2 μWh cm −2 (3.2 Wh kg −1 ). Moreover, it retains 91.19% relative to its original capacitance when subjected to a high static stretch of 200% and still maintains 87.5% capacitance after 3000 dynamic stretching cycles (at a stretching rate of 10% s −1 ). These results clearly illustrate its excellent strain-insensitivity and underscore its significant potential as an energy storage platform for wearable electronics. Download: Download high-res image (137KB) Download: Download full-size image