A metal free electrocatalyst for high-performance zinc-air battery applications with good resistance towards poisoning species

• Published in: Carbon (New York) 2020-08, Vol.164, p.12-18
• Main Authors: Najam, Tayyaba, Ahmad Shah, Syed Shoaib, Ali, Hassan, Song, Zhaoqi, Sun, Haohao, Peng, Zhengchun, Cai, Xingke
• Format: Article
• Language: English
• Subjects: Antipoisoning effect; Batteries; Carbon; Catalysts; Cobalt oxides; Dual-doped carbon; Electrocatalysis; Electrocatalysts; Electrodes; Flux density; Metal air batteries; Metal-free electrocatalyst; Nanospheres; Nitrogen dioxide; Open circuit voltage; Oxygen reduction reaction; Performance degradation; Platinum; Poisoning; Poisons; Zinc; Zinc-air battery; Zinc-oxygen batteries
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/j.carbon.2020.03.036

The trace amount of poisoning species in air, such as SOx and NOx, greatly degrade the performance of zinc-air battery, as they block the active sites of conventional metal containing electrocatalysts. To overcome this challenge, a catalyst with enhanced electrocatalytic properties and good resistance towards the small molecular poisons should be prepared. In this work, we synthesized a P, N dual-doped porous carbon nanospheres (DDPCN), which showed an Eonset and E1/2 of 0.98 V and 0.87 V for ORR reduction in alkaline solution, and a Tafel slop of 72 mV/dec, over-performing all the other metal-free catalysts and comparable with the performance of state-of-the-art Pt/C (20 wt%). Moreover, the E1/2 for DDPCN showed negligible change towards poisoning species; while the E1/2 for Pt/C and typical CoOx/CNTs displayed 10/10 mV and 24/13 mV decay by adding trace amount of SO32−/NO2− into the electrolyte solution. By using DDPCN as the electrocatalyst for zinc-air battery application, the device showed the highest open circuit voltage (1.48 V), the highest power density (224 mW cm−2) and the highest energy density (874 W h kg−1) among all metal-free catalysts, and their performances are even better than the Pt/C catalyst. Moreover, these performances showed negligible influence by the poisoning species for DDPCN based Zn-air battery, while the performances for Pt/C and CoOx/CNTs based Zn-air batteries were greatly deteriorated by the poisoning species up to 25% and 40%. Graphical illustration for structural resistance of DDPCN, CN, and CP for the incoming small molecules NOx and SOx. [Display omitted]