Super-high rate stretchable polypyrrole-based supercapacitors with excellent cycling stability

The performance and cycling stability of stretchable energy storage devices, such as supercapacitors and batteries, are limited by the structural breakdown arising from the stretch imposed and large volumetric swelling/shrinking. This work demonstrates a very facile and low-cost approach to fabricate stretchable supercapacitors with high performance and excellent cycling stability by electrochemical deposition of polypyrrole (PPy) on smartly-tailored stretchable stainless steel meshes. The fabricated solid-state supercapacitors possess a capacitance up to 170. F/g at a specific current of 0.5. A/g and it can be effectively enhanced to 214. F/g with a 20% strain. Moreover, they can be operated at a very high scan rate up to 10. V/s, which are 1-2 orders of magnitude higher than most rates for the PPy electrodes measured even in aqueous electrolytes. Even significantly, the fabricated solid-state supercapacitors under 0% and 20% strains achieve remarkable capacitance retentions of 98% and 87% at a very high specific current of 10. A/g after 10,000 cycles, respectively, which are the best for PPy-based solid-state flexible supercapacitors, to the best of our knowledge. The key factors and mechanisms to achieve such high performance are discussed. This facile and low-cost approach developed for fabricating stable and stretchable supercapacitors with high performances could pave the way for next-generation stretchable electronics.