Ultrafast laser micromachining of hard carbon/fumed silica anodes for high-performance sodium-ion capacitors

• Published in: Carbon (New York) Vol. 201; pp. 549 - 560
• Main Authors: Jo, Ajeong, Lee, Byunghak, Kim, Byeong Guk, Lim, Hyungsub, Han, Joong Tark, Jeong, Seung Yol, Kim, Jungmo, Seo, Seon Hee, Jeong, Hee Jin, Lee, Geon-Woong, Baeg, Kang-Jun, Jeong, Bosu, Park, Jong Hwan
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 05.01.2023
• Subjects: Femtosecond laser micromachining; Hard carbon anodes; Oxidized single-walled carbon nanotube cathodes; Sodium-ion capacitors; Sodium-ion capacitors; Hard carbon anodes; Oxidized single-walled carbon nanotube cathodes; Femtosecond laser micromachining
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/j.carbon.2022.09.031

The slow sodium-ion storage kinetics of battery-type electrodes limits the performance of sodium-ion capacitors (SICs) operating under high-power conditions. In this study, ultrafast laser micromachining was utilized to accelerate the sodium-ion storage kinetics of hard carbon/fumed silica (HC/f-SiO2) anodes. The ablation process involving an ultrafast femtosecond laser source enabled three-dimensional microstructuring of hot-short HC/f-SiO2 anodes with minimal photothermal damage. The microporous structure of the HC/f-SiO2 anodes facilitated the electrolyte wetting of the active materials as well as the diffusion-limited supply of sodium-ions from the bulk electrolytes. The microstructured HC/f-SiO2 anode exhibited a sodium-ion storage capacity of 370 mAh g−1, which was higher than those of unstructured HC/f-SiO2 anodes of comparable mass (298 mAh g−1) or thickness (248 mAh g−1). In addition, the rate capability of the microstructured HC/f-SiO2 anode was superior to that of the unstructured samples. Comparative full-cell tests with oxidized single-walled carbon nanotube cathodes confirmed that micromachining of the HC/f-SiO2 anode was crucial for improving the performance of the SIC full cells. This study demonstrates that ultrafast laser micromachining of HC/f-SiO2 electrodes is a facile and reliable strategy for the development of high-performance SICs. [Display omitted] •Cold ablation of hard carbons using scalable femtosecond laser micromachining.•Micropatterned hard carbons facilitating electrolyte wetting and diffusion of Na-ion.•Demonstration of ultrafast laser micromachining for high performance Na-ion capacitor.