Flexible Poly(vinyl alcohol) Polyaniline Hydrogel Film with Vertically Aligned Channels for an Integrated and Self-Healable Supercapacitor

Although supercapacitors attract tremendous attention due to their high power density, long cycle life, and high efficiency, it is still a challenge to prepare flexible and wearable supercapacitors with stable electrochemical performances during bending, twisting, and stretching. Herein, a vertically aligned and physically cross-linked poly(vinyl alcohol)-H2SO4 hydrogel (APH) film is fabricated by freezing-thawing and directional-freezing approaches, and polyaniline (PANI) is subsequently grown in situ on both sides of the APH film to generate a flexible and conductive APH-PANI film with vertically aligned channels as both polymeric electrodes and electrolyte of an integrated supercapacitor. The APH-PANI supercapacitor exhibits an outstanding specific capacitance of 25.86 mF cm(-2) at a current density of 0.05 mA cm(-2), 4.65 times its counterpart with a random network, because of the rapid transport of ions within the aligned channels between the two electrodes, which remains at 94% after 2000 charge/discharge cycles. More importantly, the APH-PANI supercapacitor not only presents excellent flexibility and stable electrochemical performances during twisting, bending, and stretching but also exhibits a superior self-healable capability by reorganizing dynamic hydrogen bonding. Thanks to the unique structure, high performance, and mechanical stability, the integrated APH-PANI supercapacitor shows a great potential for high-performance flexible devices.