Flexible direct formate paper fuel cells with high performance and great durability

• Published in: Journal of power sources 2021-04, Vol.490, p.229526, Article 229526
• Main Authors: Luo, Shijing, Wang, Yifei, Kong, Tsz Ching, Pan, Wending, Zhao, Xiaolong, Leung, Dennis Y.C.
• Format: Article
• Language: English
• Subjects: 3D printing; Direct formate fuel cell; Microfluidic fuel cell; Paper-based fuel cell; Single-flow
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2021.229526

Paper-based microfluidic fuel cells are prominent in flexible electronics, including wearable and disposable devices, such as smart packages and point-of-care diagnostics. However, the performance is generally low, and the long-term durability is questionable. In this work, we propose a flexible paper-based fuel cell with a novel cell architecture that adopts a single flow for the delivery of both the fuel and the supporting electrolyte. During cell operation, the anode is immersed in a liquid fuel with a supporting electrolyte, while the cathode is exposed to the ambient air. The performance of this cell is increased by one order of magnitude compared to the conventional co-flow cell architecture due to the enhanced mass transfer. A maximum power density of ~20 mW/cm2 and a maximum current density of 122.9 mA/cm2 are achieved, which are the highest among all reported paper-based direct formate fuel cells. Furthermore, this cell can steadily discharge at 5 mA cm−2 for more than 10 days continuously, while the morphology of the anode and the cathode before and after cell operation remains unchanged. Finally, this paper-based fuel cell can be efficiently fabricated by 3D printing, which is simple, low cost, and advantageous for paper-based fuel cell fabrication. •An innovative architecture for a single-flow paper-based fuel cell (PBFC) is proposed.•The air-breathing PBFC uses formate as fuel, which can be efficiently fabricated by printing.•A peak power density of 20 mW/cm2 and a cut-off current density of 123 mA/cm2 are achieved.•The PBFC can discharge at 5 mA cm−2 for more than 10 days continuously until fuel depletion.•The PBFC can be re-activated by refueling.