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In the recycling process of spent lithium-ion batteries, the presence of a certain amount of aluminum ions not only increases the alkali consumption for iron and aluminum removal but also affects the purity of nickel, cobalt, manganese salts, and iron phosphate, thereby hindering the preparation of battery-grade products. Herein, the precipitation process of aluminum hydroxide from supersaturated sodium aluminate solution was investigated across varying temperatures with the addition of minimal quantity of active seeds. X-ray diffraction analysis identified gibbsite and bayerite crystallization in the active seed phases. Assessment of product particle size distribution using power spectral density indicated median particle sizes of 9.70, 18.89, 35.32, and 51.78 μm at temperatures of 45, 55, 65, and 75 °C, respectively, suggesting that elevated temperatures favored product particle size growth. Additionally, to elucidate the precipitation mechanism, the kinetic equation was augmented with the inclusion of instantaneous seed coefficient and specific surface area, yielding an apparent activation energy of 83.52 kJ/mol.

Metal–air batteries are a type of electrochemical cell that generates electrical energy by combining metal and oxygen from the air. They are a promising technology for energy storage and portable devices because of their high energy density, low cost, and environmental friendliness. However, the discharge products of these batteries are notoriously difficult to decompose, resulting in a high overpotential. Recent works have shown that semiconductors can capture solar energy and store it in batteries. When exposed to light, photocatalysts generate carriers (strong redox pairs), thereby increasing the electron migration rate and significantly reducing the overpotential of the metal–air battery reaction. Nevertheless, single photocatalysts often exhibit poor cycle performance due to serious carrier recombination. This review paper begins by briefly describing the fundamentals of photoelectrochemistry and then focuses on commonly used photocathode design principles and various reported photocatalysts. It also discusses the main challenges and issues caused by light, such as photocorrosion and electrolyte decomposition. Finally, the critical issues associated with photo electrodes, electrolytes, and electrode/electrolyte interfaces are emphasized, and perspectives on the development of high-performance light-assisted metal–air batteries are presented.

Although RuO2is a potential electrocatalyst for Li–O2batteries (LOBs), its high price limits its large-scale application. Recent reports suggest that combining small amounts of RuO2with nonprecious supports is a wise choice for developing low-cost bifunctional electrocatalysts. Here, a series of cobalt-containing supports, including Co3O4, Co-NCNTFs, and NiCo2O4, are designed to support RuO2to explore their electrocatalytic performance in LOBs. Among them, RuO2@NiCo2O4exhibits significantly better catalytic activity and stability compared to the RuO2@Co3O4and RuO2@Co-NCNTF counterparts. Notably, RuO2@NiCo2O4achieved a low overpotential of 0.51 V and exceptional long-term reversibility exceeding 2000 h at a capacity limit of 1000 mAh g–1with a current density of 500 mA g–1, suggesting that the electronic conductance, microstructure, and electrochemical stability of the support are crucial factors in designing RuO2-based electrocatalysts for LOBs. This research provides valuable insights into designing cost-effective and efficient catalysts for advancing energy storage technologies.

Given the escalating global energy scarcity, there is a pressing need for advanced energy supply solutions to accommodate the evolving transportation landscape. Consequently, there has been a surge in interest surrounding lithium metal batteries, particularly Li–air batteries (LABs), which researchers have showcased for their remarkable energy density, reaching up to 3500 Wh kg–1. However, despite decades of dedicated research efforts, LABs have not yet achieved practical commercialization as a result of challenges, such as external moisture infiltration and sluggish electrochemical kinetics within the battery. In this review, we elucidate the challenges linked with oxygen-permeable membranes (OPMs) in practical LABs, particularly when operating in open environments. Subsequently, we comprehensively evaluate all developed OPMs to date, aiming to enhance the performance of LABs, focusing on both outer- and inner-type OPMs. Finally, critical issues pertaining to oxygen selectivity, permeability, water resistance, and electrolyte compatibility are underscored, with perspectives offered on the development of high-performance OPMs.