Engineering Geometric Electrodes for Electric Field-Enhanced High-Performance Flexible In-Plane Micro-Supercapacitors

In plane micro-supercapacitors that are miniaturized energy storage components have attracted significant attention due to their high power densities for various ubiquitous and sustainable device systems as well as their facile integration on various flexible/wearable platform. To implement the micro-supercapacitors in various practical applications that can accompany solid state or gel electrolyte and flexible substrates, ions must be readily transported to electrodes for achieving high power densities. Herein, we show large enhancement in electrochemical properties of flexible, in-plane micro-supercapacitor using sharp-edged interdigitated electrode design, which was simply fabricated through direct laser scribing method. The sharp-edged electrodes allowed strong electric field to be induced at the corners of the electrode fingers which led to the greater accumulation of ions near the surface of electrode, significantly enhancing the energy storage performance of micro-supercapacitors. The electric field-enhanced in-plane micro-supercapacitor showed the volumetric energy density of 1.52 Wh L⁻¹ and the excellent cyclability with capacitive retention of 95.4% after 20000 cycles. We further showed various practicability of our sharp-edged design in micro-supercapacitors by showing circuit applicability, mechanical stability, and air stability. These results present an important pathway for designing electrodes in various energy storage devices.