Janus Gold Nanowire Electrode for Stretchable Micro-Supercapacitors with Discriminative Capacitances
Micro-supercapacitors (MSCs) have drawn tremendous attention in the past several years for their applications in powering microelectronic systems. Typically, bulk metals or carbon nanomaterials are used for MSC electrodes, but either side of most of these electrodes possesses the same isotropic structure. Here, we report on stretchable MSCs based on patterned enokitake-like vertical gold nanowires (v-AuNWs). Different from previous MSC electrodes, the Janus v-AuNWs can have their “enokitake head” or “enokitake tail” exposed to electrolyte, leading to head-exposed MSC (H-MSC) and tail-exposed MSC (T-MSC), respectively. The H-MSC reveals higher capacitance under small scan rate but experiences obvious decrease under increasing scan rates, due to better conductivity of closely packed gold nanoparticles but less ideal ion penetration. In contrast, T-MSC with separate nanowire structure which is favorable for ion penetration, exhibits perfect rectangular-shaped cyclic voltammetry with superior rate capability and cycling stability, yet able to function under 110% of strain with negligible deterioration. Further electrodeposition of polyaniline could enhance the specific capacitance to 5.03 mF/cm2. The facile fabrication also reduces the complexity of preparation procedures compared to previous extrinsically stretchable designs. Those results demonstrate that our Janus enokitake-like v-AuNWs hold great potential in building future soft, stretchable microelectronics.