EGaIn Fiber Enabled Highly Flexible Supercapacitors.

Attributed to their soft and stretchable feature, flexible supercapacitors have attracted increasing attention in areas of soft electronics, wearable devices, and energy storage systems. However, it is a challenge to manufacture all-soft supercapacitors with highly flexible properties and excellent electrochemical performance. Here, an EGaIn-based fibrous supercapacitor, which is composed of two paralleled stretchable fibers, is designed and demonstrated first with flexible and stretchable properties. EGaIn coated on the surface of polyurethane (PU)@polymethacrylate (PMA) fibers can serve as a current collector. The prepared supercapacitor is measured with an areal specific capacitance of 26.71 mF·cm-2 by mixing Fe3O4 microparticles with EGaIn. This value can increase up to 61.34 mF·cm-2 after vacuum pumping, the mechanism of which is further revealed to be related with the coarser surface and airhole formation on the fibers. The supercapacitor maintains an excellent electrochemical performance when stretched to 120% strain and exhibits a long cycling life through a charge-discharge cycle of over 1000 times. Finally, the supercapacitors are adopted to light the LED, demonstrating that those supercapacitors can work successfully. All these characteristics indicate the huge potential of EGaIn-based supercapacitors in the field of flexible electronics and wearable devices.