Sponge integrated highly compressible all-solid-state supercapacitor with superior performance†
Abstract
Compressible supercapacitors are novel energy-storage devices that can be used in elastic electronics; however, the performance of the supercapacitor depends mainly on its electrode materials and configuration. Herein, free-standing three-dimensional hierarchical porous polypyrrole (PPy) wrapped nitrogen-containing polyaniline based carbon nanospheres (NPACNS) are prepared and coated on the skeleton of sponge composite electrodes (PPy/NPACNS/sponge) via dipping and drying and chemical oxidation polymerization methods. Furthermore, an integrated highly compressible all-solid-state supercapacitor is fabricated using PPy/NPACNS/sponge as the electrode and polyvinyl alcohol (PVA)/LiClO4 gel as the electrolyte, which demonstrates an outstanding electrochemical performance of 95 F g−1 (2.8 F cm−3) specific capacitance, 3.3 W h kg−1 (0.1 mW h cm−3) energy density and 93% capacitance retention after 1000 cycles. Surprisingly, the electrochemical performance of the as-fabricated device remains nearly unchanged when it is compressed under 50% strain, and its specific capacitance and compressibility are well maintained after 400 repeated compressing-releasing cycles. More importantly, due to its solid-state and integrated configuration, several compressible supercapacitors can be conveniently interconnected together in series on one chip to power electronics. This device will pave the way for advanced supercapacitor applications in compressible energy storage devices that are compatible with compression-tolerant electronics.