Elastic soft hydrogel supercapacitor for energy storage†
High-performance supercapacitors, as highly promising candidates for bridging the gap between conventional lithium-ion batteries and traditional electrostatic capacitors, are the key to progress in the field of energy storage. To improve the performance of supercapacitors, the exploration of novel functional electrode materials is always at the forefront of technology. Herein, the rational design of a novel deformable soft supercapacitor, which is based on a compressible capacitive polyvinyl alcohol/polypyrrole (PVA/PPy) composite hydrogel and a flexible carbon nanotubes (CNTs) film, is reported. Due to the unique layered wrinkle structure of the PVA/PPy composite hydrogel, whose internal structure contains a large amount of water, the fabricated supercapacitor exhibits fascinating mechanical properties, including elasticity, compressibility and softness. In addition, the CNTs self-supported film without any binder shows an excellent flexibility as well as a stable capacitance in long-term cycles, which results in an enhanced cycle performance of the (PVA/PPy)(−)//CNTs(+) supercapacitor. Furthermore, the (PVA/PPy)(−)//CNTs(+) supercapacitor exhibits a high working voltage (0–2 V) accompanied with an energy density of 33.3 W h kg−1 (a power density of 1600 W kg−1). The high-performance compressible soft supercapacitor with deformability heralds a new territory of hydrogel-based supercapacitor for energy storage applications.