On-Chip Micro-Supercapacitor with High Areal Energy Density Based on Dielectrophoretic Assembly of Nanoporous Metal Microwire Electrodes
Abstract
Advances in the Internet of Things (IoT) technology have driven the demand for miniaturized electronic devices, prompting research on small-scale energy-storage systems. Micro-supercapacitors (MSCs) stand out in this regard because of their compact size, high power density, high charge-discharge rate, and extended cycle life. However, their limited energy density impedes commercialization. To resolve this issue, a simple and innovative approach is reported herein for fabricating highly efficient on-chip MSCs integrated with nanoporous metal microwires formed by dielectrophoresis (DEP)-driven gold nanoparticle (AuNP) assembly. Placing a water-based AuNP suspension onto interdigitated electrodes and applying an alternating voltage induces in-plane porous microwire formation in the electrode gap. The DEP-induced AuNP assembly and the gold microwire (AuMW) growth rate can be adjusted by controlling the applied alternating voltage and frequency. The microwire-integrated MSC (AuMW-MSC) electrically outperforms its unmodified counterpart and exhibits a 30% larger electrode area, along with 72% and 78% higher specific and areal capacitances, respectively, than a microwire-free MSC. Additionally, AuMW-MSC achieves maximum energy and power densities of 3.33 mu Wh cm-2 and 2629 mu W cm-2, respectively, with a gel electrolyte. These findings can help upgrade MSCs to function as potent energy-storage devices for small electronics. This study presents an efficient on-chip micro-supercapacitor (MSC) constructed via the dielectrophoretic assembly of nanoporous Au microwires in the spaces between interdigitated microelectrodes. The large electrode surface area of the microwire-integrated MSC significantly enhances the electrochemical performance and areal energy density. This fabrication strategy shows considerable promise for realizing on-chip energy-storage devices that can power wearable and IoT devices. image
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