Highly Stretchable Microsupercapacitors Based on Hot-Press Transferred Single-Walled Carbon Nanotubes with a Hybrid Acid Electrolyte

Stretchable energy storage devices are highly demanded in wearable electronics. Herein, a high-performance stretchable microsupercapacitor (MSC) based on wrinkled hydroxylated single-walled carbon nanotubes (SWCNT–OH) with silicotungstic acid (SiWA) and phosphoric acid (H 3 PO 4 ) hybrid electrolyte has been developed. The wrinkled SWCNT electrodes were constructed on prestretched thermoplastic polyurethane (TPU) fabric substrates by hot-pressing techniques. This endows the device with 100% uniaxial stretchability. Compared to the H 3 PO 4 electrolyte, the SiWA electrolyte was found to broaden the voltage window (−0.8 to 0.8 V) and provide additional pseudocapacitance. A specific areal capacitance of 21.41 mF cm –2 can be achieved by MSCs featuring wrinkled SWCNTs and utilizing the SiWA–H 3 PO 4 electrolyte at 5 mV s –1, being around 30 times higher than the MSCs solely using the H 3 PO 4 electrolyte without a prestretching strategy. In addition, even after 10,000 charge/discharge cycles, the capacitor retains its capacity at a high level of 96.3%. Due to the robust adhesion between SWCNTs and the TPU substrate via hot-press transfer, the device maintained stable performance after undergoing water-washing and friction tests, demonstrating excellent mechanical durability and electrochemical reliability. This research provides a viable solution for wearable flexible energy storage devices, which creates possibilities for the evolution of energy storage technologies within next-generation flexible electronic devices.