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.