Nanocomposites of Carbon for Metal-Air Batteries

Extensive studies are being made on clean and sustainable energy conversion technologies to harness their potential in terms of great efficiency, large-scale uses, and negligible greenhouse gas emissions including fuel cells, metal-air batteries, and water-splitting techniques. Among them all, metal-air batteries are the most promising systems for portable electronic devices, electrical vehicles, and stationary microgrid applications due to their high energy density. However, the major limitation is the fundamental issues with their mechanism. The efficiency of energy conversion and storage is controlled by the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), which are generally very slow and require noble metal catalysts for fast operation. The high cost and limited availability of noble metals caused a growing interest in developing metal-free carbons as a novel class of bifunctional electrocatalysts. These materials display exceptional strength, stability, conductivity, large surface area, and high stability in both acidic and alkaline environments and therefore can play a significant role in the field of clean energy storage/conversion technologies. In this chapter, the recent advances regarding the rational design of carbon-based electrocatalysts for the oxygen reduction reaction and oxygen evolution reaction are summarized, with a special focus on their applications in Zn–air and Li–air batteries.