Wednesday, 12 October 2022
S. Thankappakurup (CSIR-Central electrochemical research institute), K. Mathialagan (CSIR-Central electrochemical research institute, Academy of scientific and innovative research (AcSIR), Ghaziabad), D. Dixon (Academy of Scientific and Innovative Research (AcSIR), CSIR-Central electrochemical research institute), A. T (Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, CSIR-Central Electrochemical Research Institute), and S. T. Nishanthi (CSIR, (Central Electrochemical Research Institute) CECRI, (Academy of Scientific and Innovative Research) AcSIR, Ghaziabad)
Zinc-air batteries are cost-effective batteries that possess a high energy density (1086 Wh Kg
-1), compared to other conventional battery systems. In order to improve the electrochemical performance of electrically rechargeable zinc-air batteries (ERZABs), an effective bifunctional oxygen electrocatalyst is required. Hence, the development of non-noble metal bifunctional catalysts for ORR and OER is of prime importance. The transition metal-based catalysts have increasing demand since they are promising alternatives, in terms of cost and durability, to noble metal catalysts. Metal-organic frameworks (MOF) based catalysts show high catalytic activity due to adjustable pore size, ultra-high surface area, and structural designability
[1].
Increasing porosity can augment the catalytic activity by increasing the surface area, thereby enhancing the ORR kinetics.
In the present work, a CFZ-NPC (CoFeZn-MOF derived nanoporous carbon) was synthesized via hydrothermal method and investigated as a bifunctional catalyst for rechargeable zinc-air batteries[2]. The catalyst shows a high electrochemical activity towards oxygen reduction reaction with a half-wave potential of 830 mV vs. RHE and a comparable oxygen evolution activity (overpotential of 379 mV vs. RHE at 10 mA cm-2 ) with IrO2 (Over potential of 377 mV at 10 mA cm-2). The binder-free CFZ-NPC air electrode when applied into a Zinc-air battery system, delivers a low charge-discharge potential gap of 862 mV at 5 mA cm-2. Interestingly, the catalyst possesses an excellent electrochemical performance in the electrically rechargeable Zn-air battery over 1000 cycles at selected DOD for 157 h with a specific capacity of 890 mAh g(Zn)-1 without much efficiency drop.
Financial support from Department of Science and Technology, Govt. of India under research grant number DST/TMD/MECSP/2K17/20 is gratefully acknowledged
References;
[1] Ren, Shuangshuang et al. 2020. “Bifunctional Electrocatalysts for Zn-Air Batteries: Recent Developments and Future Perspectives.” Journal of Materials Chemistry A 8(13): 6144–82.
[2] Tang, Jing et al. 2016. “Bimetallic Metal-Organic Frameworks for Controlled Catalytic Graphitization of Nano porous Carbons.” Nature Publishing Group (April): 1-8.
