A 3D-printed stretchable structural supercapacitor with active stretchability/flexibility and remarkable volumetric capacitance

With the rapid growth and advance in the Internet of things and flexible/on-skin electronics, stretchable/flexible energy storage devices are being unprecedentedly needed and widely pursued. However, it remains a great challenge to realize devices with both high storage capacity and satisfactory mechanical stretchability/flexibility. Herein, by synergistically combining 3D printing with electrodeposition, a 3D-printed stretchable structural supercapacitor with thick electrodes and a 3D Negative Poisson's Ratio (NPR) multicellular framework was developed. Benefiting from the well-designed NPR lattice electrode architecture and unique 3D nanoflower-on-nanosheet structured CoNi2S4/NiCo-LDHs nanocomposites, the assembled stretchable symmetric supercapacitor was highly stretchable (up to ∼55%) and flexible (up to 180°) with a favorable capacitance of 28.71 F cm-3, superior energy density of 0.582 mW h cm-3 and satisfied stability in stretching and bending cycles (75.2% of its initial capacitance after 1000 periodic stretch/release cycles), which are highly comparable to those obtained for previously reported stretchable supercapacitors. The strategy proposed here provides new insights in developing next-generation highly customized 3D structural strengthening energy storage devices for human-machine interfaces and real wearable and intelligent miniaturized electronics.