Exploring the Effect of Ultrafast Intensive Pulsed Light (IPL) Annealing on the Structure and Performance of Cobalt Oxide Electrodes for Supercapacitors
Ninad B. Velhal, Junhyuck Ahn, Tae Ho Yun, Tae‐Wook Kim, Minsu Gu, Jisoo Kim, Changyong Yim
Abstract
In this study, a cobalt oxide (Co 3 O 4 ) supercapacitor electrode is prepared using ultrafast annealing to enhance its supercapacitive performance. The Co 3 O 4 active materials, synthesized through hydrothermal synthesis, are heat-treated using a conventional muffle furnace (constant heat annealing (CHA)) and ultrafast intensive pulsed light (IPL) flash annealing (instant heat annealing (IHA)). Structural and morphological analysis reveals that CHA Co 3 O 4 has a nano-rope structure with micro-sheets. In contrast, IHA Co 3 O 4 exhibits a coral reef-like morphology with a high surface area and a melted ice-like structure. Despite this change in morphology, the crystal structure of the Co 3 O 4 remains unchanged after ultrafast IPL treatment. The resulting electrochemical properties show that the pseudocapacitive nature of IHA Co 3 O 4 leads to a twofold increase in areal capacitance (955.73 mF/cm 2 ) compared to CHA Co 3 O 4, as well as excellent cyclic stability (90.81% in average over 10,000 galvanostatic charge–discharge cycles). The mechanisms behind the improved performance of IHA Co 3 O 4, which include the unique coral reef morphology, are thought to increase the facile intercalation of ions and reduce the diffusion path for faster charge transfer reactions. Assembled hybrid asymmetric supercapacitors (ASC) show a specific capacitance of 128.13 F/g at 3 mA/cm 2 with 98.67% excellent retention capability of its initial capacitance over the 5000 galvanostatic charge–discharge (GCD) cycles. This study presents a simple, low-cost, and ultrafast approach for fabricating high-performance and stable electrode materials for energy storage applications.