A Mechanistic Overview of the Current Status and Future Challenges in Air Cathode for Aluminum Air Batteries.

Aluminum air batteries (AABs) are a desirable option for portable electronic devices and electric vehicles (EVs) due to their high theoretical energy density (8100 Wh K-1 ), low cost, and high safety compared to state-of-the-art lithium-ion batteries (LIBs). However, numerous unresolved technological and scientific issues are preventing AABs from expanding further. One of the key issues is the catalytic reaction kinetics of the air cathode as the fuel (oxygen) for AAB is reduced there. Additionally, the performance and price of an AAB are directly influenced by an air electrode integrated with an oxygen electrocatalyst, which is thought to be the most crucial element. In this study, we covered the oxygen chemistry of the air cathode as well as a brief discussion of the mechanistic insights of active catalysts and how they catalyze and enhance oxygen chemistry reactions. There is also extensive discussion of research into electrocatalytic materials that outperform Pt/C such as nonprecious metal catalysts, metal oxide, perovskites, metal-organic framework, carbonaceous materials, and their composites. Finally, we provide an overview of the present state, and possible future direction for air cathodes in AABs.

Poly[(2-methacryloyloxy)Ethyl]Trimethylammonium Chloride Supported Cobalt Oxide Nanoparticles as an Active Electrocatalyst for Efficient Oxygen Evolution Reaction.

To combat with energy crisis considering clean energy, oxygen evolution reaction (OER) is crucial to implement electrolytic hydrogen fuel production in real life. Here, straightforward chemical synthesis pathways are followed to prepare cobalt tetraoxide nanoparticles (Co3O4NPs) in an alkaline OER process using poly[(2-methacryloyloxy)ethyl]trimethylammonium chloride (Co3O4NPs@PMTC) as support to prevent aggregation. In material characterization, the X-ray diffraction (XRD) pattern confirms the crystallinity of the synthesized Co3O4NPs@PMTC, and Raman spectroscopy indicates that the Co3O4NPs contain cubic close-packed oxides. The morphological analysis reveals the wrinkle-like disruption which is distributed evenly owing to the folded nanosheet arrays. Energy-dispersive X-ray spectroscopy indicates the presence of a significant number of cobalt atoms in the Co3O4NPs, and elemental mapping analysis demonstrates the composition of the NPs. At a current density of 10 mA cm-2, oxygen is emitted at 1.67 V delivering an overpotential of 440 mV. This unique structure of Co3O4NPs@PMTC provides beneficial functions that are responsible for a large number of active sites and the rapid release of oxygen gas with long-term stability. Through kinetic study, we found a Tafel slope of 48.9 mV dec-1 which proves the catalytic behavior of Co3O4NPs@PMTC is promising toward the OER process.

Designing High-Performing Symmetric Supercapacitor by Engineering Polyaniline on Steel Mesh Surface via Electrodeposition.

Energy storage is one of the most stimulating requirements to keep civilization on the wheel of progress. Supercapacitors generally exhibit a high-power density, have a maximum life cycle, quick charging time, and are eco-friendly. Polyaniline (PANI), a conductive polymer, is considered an efficacious electrode material for supercapacitors due to its good electroactivity, including pseudocapacitive behavior. Here, we present the fabrication of a symmetric supercapacitor device based on steel mesh electrodeposited with PANI. Due to its effective conductivity, porous nature, and low cost, steel mesh is a good choice as a current collector to fabricate a high-performance supercapacitor at a low cost. The optimum fabricated supercapacitor has a high specific capacitance of ∼353 mF cm-2 . Furthermore, the supercapacitor obtained an energy density of ∼26.4 µW h cm-2 at a power density of ∼400 µW cm-2 . The fabricated supercapacitor shows high stability, as the initial capacitance remained almost the same after 1000 charge/discharge cycles. PANI is a promising candidate for mass production and wide applications due to its low cost and high performance.