Ultra-stretchable supercapacitors based on biaxially pre-strained super-aligned carbon nanotube films

Super-aligned carbon nanotube (SACNT) films with wrinkled structures are prepared by a biaxial pre-strain method and can withstand repetitive stretching of large strains in multiple directions. Ultra-stretchable supercapacitors were fabricated with the SACNT film and active carbon (AC) powders. The initial specific capacitance without strain and with 150% strains in the X, Y and 45° axes was 91, 88, 89 and 90 F g^-1, respectively. Moreover, the capacitance retentions were 97%, 98.5% and 98.6% after 2000 tensile cycles at 0-150% strain in the X, Y and 45° axes, respectively, demonstrating the excellent strain durability of the SACNT/AC supercapacitors. The stretchable circuit with the combination of stretchable SACNT/AC supercapacitors and SACNT conductors demonstrates a promising method in developing self-contained stretchable functional devices for a variety of applications. The low-cost and scalable biaxial pre-strain process presents a potential route for designing high performance stretchable electronic and energy storage devices.