A Wearable Second Skin‐Like Multifunctional Supercapacitor with Vertical Gold Nanowires and Electrochromic Polyaniline

An ideal wearable/implantable bio-diagnostics can be powered by second skin-like energy devices in that they offer advantages such as conformal attachment/integration, lightweightness, and moduli-matching properties. Past several years have witnessed encouraging progresses in soft stretchable supercapacitors by various material combinations and design strategies; however, it remains nontrivial to achieve highly flexible high-performance supercapacitors in a skin-thin layout yet with multifunctionality. Here, such a second skin-like electrochromic supercapacitor is demonstrated using self-assembled vertical gold nanowires (v-AuNWs) and electrodeposited polyaniline (PANI). The v-AuNW film is highly conductive yet offers great flexibility and deformability, while PANI plays a dual role in enhancing capacitance and as charge/discharge-level indicator. The assembled supercapacitors offer superior skin-conformability and could achieve an areal specific capacitance of 11.76 mF cm(-2) (scan rate of 10 mV s(-1)) with high durability. A second skin-like wearable tattoo energy device can be designed with negligible performance deterioration under multiple hand movements and skin deformations.