A Long Cycle‐Life High‐Voltage Spinel Lithium‐Ion Battery Electrode Achieved by Site‐Selective Doping

Spinel LiNi_0.5Mn_1.5O₄ (LNMO) is a promising cathode candidate for the next‐generation high energy‐density lithium‐ion batteries (LIBs). Unfortunately, the application of LNMO is hindered by its poor cycle stability. Now, site‐selectively doped LNMO electrode is prepared with exceptional durability. In this work, Mg is selectively doped onto both tetrahedral (8a) and octahedral (16c) sites in the Fd m structure. This site‐selective doping not only suppresses unfavorable two‐phase reactions and stabilizes the LNMO structure against structural deformation, but also mitigates the dissolution of Mn during cycling. Mg‐doped LNMOs exhibit extraordinarily stable electrochemical performance in both half‐cells and prototype full‐batteries with novel TiNb₂O₇ counter‐electrodes. This work pioneers an atomic‐doping engineering strategy for electrode materials that could be extended to other energy materials to create high‐performance devices.     

Alkaline fuel cells: Calculating and comparing overall currents of hydrophobized cathodes with thin regular-structure and thick stochastic-structure active layers

A concept of active hydrophobized active layers with regular structure is introduced. In these layers, a hydrophobizer takes part in the development of gas pores representing a set of straight identical rods (cylinders) uniformly distributed over the active layer and extended in a direction perpendicular to the cathode surface. An advantage of cathodes with a thin regular-structure active layer is the reproducibility of their characteristics and a low content of platinum catalyst (up to tenth and even hundredth fractions of mg/cm²). A comparison of current characteristics of thin (with the thickness of several tens of μm) active layers with a regular structure and thick (with the thickness of several hundreds of μm) with the stochastic distribution of the hydrophobizer (with randomly distributed polytetrafluoroethylene) is made. For a fuel cell with an alkaline electrolyte (7 M KOH at 60°C), calculations show that at potentials below 0.5 V (RHE), the cathodes with thin regularstructure active layers demonstrate higher overall currents as compared with cathodes covered with thick active layers with a stochastic structure. However, the opposite trend is observed at potentials above 0.5 V. To increase the current in cathodes with thin regular-structure active layers, it is possible to, first, increase the active layer thickness and, second, decrease the size of hydrophobizer grains in them.     

Pivotal Role of Organic Materials in Aqueous Zinc-Based Batteries: Regulating Cathode,Anode, Electrolyte,and Separator

Aqueous zinc-based batteries have garnered considerable interest as promising energy storage devices due to the low cost, remarkable energy density, high safety, and eco-friendliness. However, the mutual challenges of cathode dissolution, electrolyte parasitic reactions, disordered zinc dendrite growth, and easily punctured separator have significantly impeded the widespread commercialization of aqueous zinc-based batteries. Realizing high-performance zinc-based batteries becomes imperative yet remains extremely challenging. To address these concerns, great efforts have recently been made to design high-performance zinc-based batteries. Here the state-of-the-art in organic materials is critically reviewed for aqueous zinc-based batteries, covering main components of a battery. This review provides a comprehensive overview on the design strategies of organic materials for zinc-based batteries, encompassing cathode, anode, electrolyte, and separator. Furthermore, the challenges and prospective research directions are also discussed to provide a guideline for further development of highly stable zinc-based batteries.     

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.     

Porous Carbon Hosts for Lithium–Sulfur Batteries

Lithium–sulfur batteries (LSBs) are considered to be one of the most promising alternatives to the current lithium-ion batteries (LIBs) to meet the increasing demand for energy storage owing to their high energy density, natural abundance, low cost, and environmental friendliness. Despite great success, LSBs still suffer from several problems, including undermined capacity arising from low utilization of sulfur, unsatisfactory rate performance and poor cycling life owing to the shuttle effect of polysulfides, and poor electrical conductivity of sulfur. Under such circumstances, the design/fabrication of porous carbon–sulfur composite cathodes is regarded as an effective solution to overcome the above problems. In this review, different synthetic methods of porous carbon hosts and their corresponding integration into carbon–sulfur cathodes are summarized. The pore formation mechanism of porous carbon hosts is also addressed. The pore size effect on electrochemical performance is highlighted and compared. The enhanced mechanism of the porous carbon host on the sulfur cathode is systematically reviewed and revealed. Finally, the combination of porous carbon hosts and high-profile solid-state electrolytes is demonstrated, and the challenges to realize large-scale commercial application of porous carbon–sulfur cathodes is discussed and future trends are proposed.     

Microwave‐Assisted Solvothermal Synthesis of VO2 Hollow Spheres and Their Conversion into V2O5 Hollow Spheres with Improved Lithium Storage Capability

Monodispersed hierarchically structured V₂O₅ hollow spheres were successfully obtained from orthorhombic VO₂ hollow spheres, which are in turn synthesized by a simple template‐free microwave‐assisted solvothermal method. The structural evolution of VO₂ hollow spheres has been studied and explained by a chemically induced self‐transformation process. The reaction time and water content in the reaction solution have a great influence on the morphology and phase structure of the resulting products in the solvothermal reaction. The diameter of the VO₂ hollow spheres can be regulated simply by changing vanadium ion content in the reaction solution. The VO₂ hollow spheres can be transformed into V₂O₅ hollow spheres with nearly no morphological change by annealing in air. The nanorods composed of V₂O₅ hollow spheres have an average length of about 70 nm and width of about 19 nm. When used as a cathode material for lithium‐ion batteries, the V₂O₅ hollow spheres display a diameter‐dependent electrochemical performance, and the 440 nm hollow spheres show the highest specific discharge capacity of 377.5 mAhg^?1 at a current density of 50 mAg^?1, and are better than the corresponding solid spheres and nanorod assemblies.     

LiFePO4：水热合成及性能研究

LiFePO4是继尖晶石型LiMn2O4[1]之后的一种新型锂离子电池正极材料,其具有结构稳定,工作电位适中(3.45VvsLi/Li )、可逆容量高、无毒价廉等优点,被认为是极具发展潜力的锂离子电池正极材料[2]。有关LiFePO4的结构[3]和性能[4]研究引人关注。目前,LiFePO4主要是采用高温固相法[5]来合成,尽管简单方便,但由于该传统方法的局限性,很难得到纯度高、粒径小、电性能好的LiFePO4。因此人们尝试用微波加热[6]、溶胶-凝胶[7]、共沉淀[8]等制备方法,希望得到理想的LiFePO4材料,但是采用水热法制备LiFePO4鲜见报道。本文采用水热法制备了纯…     

A Yolk–Shell‐Structured FePO4 Cathode for High‐Rate and Long‐Cycling Sodium‐Ion Batteries

Amorphous iron phosphate (FePO₄) has attracted enormous attention as a promising cathode material for sodium‐ion batteries (SIBs) because of its high theoretical specific capacity and superior electrochemical reversibility. Nevertheless, the low rate performance and rapid capacity decline seriously hamper its implementation in SIBs. Herein, we demonstrate a sagacious multi‐step templating approach to skillfully craft amorphous FePO₄ yolk–shell nanospheres with mesoporous nanoyolks supported inside the robust porous outer nanoshells. Their unique architecture and large surface area enable these amorphous FePO₄ yolk–shell nanospheres to manifest remarkable sodium storage properties with high reversible capacity, outstanding rate performance, and ultralong cycle life.     

Glassy carbon modified by a silver-palladium alloy: cheap and convenient cathodes for the selective reductive homocoupling of alkyl iodides

Micrometer-thick layers of silver-palladium alloy were elaborated in order to modify the surface of glassy carbon electrodes. Such a surface modification can be readily achieved via a preliminary silver galvanostatic deposit onto carbon followed by a ‘palladization’ step, thanks to a simple immersion in acidic Pd^II-based solutions producing a displacement reaction. The as-prepared metallic interfaces exhibit outstanding catalytic capabilities especially in the cleavage of carbon-halogen bonds while being chemically/electrochemically quite stable and relatively inexpensive. More specifically, the use of such glassy carbon/Ag-Pd electrodes in dimethylformamide (DMF) containing tetraalkylammonium salts (TAA⁺X⁻) makes the one-electron reductions of primary alkyl iodides possible; this reduction leads to the formation of homodimers in high yields. Formation of a free radical as transient resulted from the homocoupling reaction.