Ultra-stable air electrodes based on different carbon materials for zinc-air battery

Air electrode is an indispensable crucial component of metal-air batteries and its performance is determined by many factors. Among them, the structure of the gas diffusion layer has a great influence on the overall performance of an air electrode. In this work, different carbon materials such as acetylene black (AB), graphite (GP), carbon nanotube (CNT), and their mixtures are taken to construct the gas diffusion layer of an air electrode to significantly improve the gas transport efficiency of the diffusion layer. The results show that the air electrode AB(2)@CNT8, which is composed of AB and CNT with the mass ratio of 2:8, reveals superior oxygen reduction reaction (ORR) performance compared to the AB air electrode fabricated with the conventional carbon material AB. Further, we applied the air electrodes AB(2)@CNT8 and AB to alkaline zinc-air batteries and investigated their discharge performance. Tests show that compared to the AB zinc-air battery, the AB(2)@CNT8 battery exhibits higher output power and discharge specific capacity of up to 704 mAh<middle dot>g(Zn)(-1). In addition, during the ultra-long time constant current (5 mA) discharge test, the AB(2)@CNT8 battery can run stably for 1430 h continuously by simply replacing anode Zn sheet and electrolyte, while maintaining a relatively stable discharge voltage. Meanwhile, the performance of the air electrode AB(2)@CNT8 after long-term operation can be rapidly restored by a simple hot water treatment. Comprehensive testing of the air electrode AB(2)@CNT8 is a testament to its powerful and excellent long life, good cyclic discharge stability, and durability. This shows that changing the type of carbon materials and regulating the mixing ratio between various carbon materials will be an effective means to design and optimize the structure of the air cathode. In addition, the air electrode preparation method of the present investigation has the characteristics of simple synthesis process, easy operation, safety and environmental friendliness, and low cost. The work provides a new strategy for the industrial-scale production of stable and efficient air electrodes.