A stretchable piezo-supercapacitor derived from piezo-hydrogel and polypyrrole elastomer for tensile strain energy harvesting

Piezo-supercapacitors have been developed to collect human motion energy but tensile strain energy harvesting through piezo-supercapacitor is little explored. In this work, a stretchable piezo-supercapacitor SSP PPy-BTO is constructed from hydrogel piezo-electrolyte HPE SA-BTO and polypyrrole elastomer electrode for self-charging by tensile deformation. HPE SA-BTO is fabricated by in situ polymerization of acrylamide in aqueous sulfuric acid solution containing uniformly dispersed barium titanate particles. HPE SA-BTO delivers an ionic conductivity of 97.3 mS cm −1 and an open circuit voltage of 2619 mV under a compressive force of 3.5 N. Sandwiching HPE SA-BTO between elastic poly (2-hydroxy ethyl acrylate)- co -polypyrrole electrodes gives SSP PPy-BTO , which exhibits a stretchability of 286 % and a specific capacitance of 218 mF cm −2 . SSP PPy-BTO successfully harvests energy from axial stretch to charge itself in the lateral direction through transverse deformation of HPE SA-BTO . The self-charged voltage increases with the increase in tensile strain and attains 567 mV at 60 % strain. A single SSP PPy-BTO with an effective area of 2 cm 2 is self-charged by the energy from flexing a finger and properly powers an electronic watch. The work offers insights into the tensile strain energy harvesting and is helpful for proper design of stretchable piezo-supercapacitors.