Fabrication of a stretchable and patchable array of high performance micro-supercapacitors using a non-aqueous solvent based gel electrolyte
In this study, we report the fabrication of a stretchable and patchable array of micro-supercapacitors (MSCs) using a gel-type electrolyte of poly(methyl methacrylate)–propylene carbonate–lithium perchlorate. As electrodes, a layer-by-layer-assembled thin film of multi-walled carbon nanotubes with a top layer of Mn3O4 nanoparticles was used. The fabricated MSC maintained over 85% of its performance for 2 weeks in ambient air without encapsulation owing to the use of a non-aqueous solvent based gel electrolyte. Dry-transferred MSC arrays on a specially designed stretchable polymer substrate exhibited stable electrochemical performance under various deformations, including bending, twisting, both uniaxial and biaxial stretching up to 50%, and winding around the curved substrate. Furthermore, the encapsulated MSC array with a thin polymer film directly attached to skin maintained its electrochemical performance under repeated body movement, cycles of attachment–detachment, and even in water. This study clearly demonstrates a stretchable and patchable MSC array for practical use as an energy storage device that can be attached to the body for electronic function, even under wet conditions.