Three-dimensional nitrogen and phosphorous Co-doped graphene aerogel electrocatalysts for efficient oxygen reduction reaction

The role of graphene aerogels in rechargeable batteries

Energy storage systems, particularly rechargeable batteries, play a crucial role in establishing a sustainable energy infrastructure. Today, researchers focus on improving battery energy density, cycling stability, and rate performance. This involves enhancing existing materials or creating new ones with advanced properties for cathodes and anodes to achieve peak battery performance. Graphene aerogels (GAs) possess extraordinary attributes, including a hierarchical porous and lightweight structure, high electrical conductivity, and robust mechanical stability. These qualities facilitate the uniform distribution of active sites within electrodes, mitigate volume changes during repeated cycling, and enhance overall conductivity. When integrated into batteries, GAs expedite electron/ion transport, offer exceptional structural stability, and deliver outstanding cycling performance. This review offers a comprehensive survey of the advancements in the preparation, functionalization, and modification of GAs in the context of battery research. It explores their application as electrodes and hosts for the dispersion of active material nanoparticles, resulting in the creation of hybrid electrodes for a wide range of rechargeable batteries including lithium-ion batteries (LIBs), Li-metal-air batteries, sodium-ion batteries (SIBs), zinc-ion batteries (AZIBs) and zinc-air batteries (ZABs), aluminum-ion batteries (AIBs) and aluminum-air batteries and other.

Molten-salt-assisted preparation of porous carbon foams for efficient oxygen electrocatalysis in zinc-air batteries

To enhance the reversible electrolytic conversion of oxygen in zinc-air batteries, a molten-salt-assisted method was demonstrated to synthesize highly porous carbon foams with in situ anchoring of metal sites. These electrocatalysts improved the electrolysis for oxygen reduction and evolution reactions, thus leading to the fabrication of advanced zinc-air batteries.

Recent progress in pyrolyzed carbon materials as electrocatalysts for the oxygen reduction reaction

This review reports some recent advances in pyrolytic carbon as an ORR catalyst and explores its structure–activity relationship.

Atomic Modulation and Structure Design of Carbons for Bifunctional Electrocatalysis in Metal-Air Batteries

With the extensive research and development of renewable energy technologies, there is an increasing interest in developing metal-free carbons as a new class of bifunctional electrocatalysts for boosting the performance of metal-air batteries. Along with significant understanding of the electrocatalytic nature and the rapid development of techniques, the activities of carbon electrocatalysts are well-tailored by introducing particular dopants/defects and structure regulation. Herein, 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 the bifunctional applications in Zn-air and Li-air batteries. Specifically, the atomic modulation strategies to regulate the electrocatalytic activities of carbons and structure modification are summarized to gain deep insights into bifunctional mechanisms and boost advanced Zn-air and Li-air batteries. The current challenges and future perspectives are also addressed to accelerate the exploration of promising bifunctional carbon catalysts for renewable energy technologies, particularly metal-air batteries.

Recent Advances in Materials and Design of Electrochemically Rechargeable Zinc-Air Batteries

The century-old zinc-air (Zn-air) battery concept has been revived in the last decade due to its high theoretical energy density, environmental-friendliness, affordability, and safety. Particularly, electrically rechargeable Zn-air battery technologies are of great importance for bulk applications like electric vehicles, grid management, and portable electronic devices. Nevertheless, Zn-air batteries are still not competitive enough to realize widespread practical adoption because of issues in efficiency, durability, and cycle life. Here, following an introduction to the fundamentals and performance testing techniques, the latest research progress related to electrically rechargeable Zn-air batteries is compiled, particularly new key findings in the last five years (2013-2018). The strategies concerning the development of Zn and air electrodes are in focus. The design of other battery components, namely electrolytes and separators are also discussed. Poor performance of O₂ electrocatalysts and the lack of the long-term stability of Zn electrodes and electrolytes remain major challenges. Finally, recommendations regarding the testing routines and materials design are provided. It is hoped that this up-to-date account will help to shape the future research activities toward the development of practical electrically rechargeable Zn-air batteries with extended lifetime and superior performance.