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Realizing long-life cycling is the biggest challenge in the research field of Li-O₂ batteries in the current stage. The main reasons for poor cycling performance are the sluggish Li₂O₂ formation and decomposition process, as well as the side reaction of carbon cathode. In order to accurately address the problems above, a TiO₂/CNTs cathode was rationally designed for long-life Li-O₂ batteries. The CNTs skeleton offers multiple three-dimensional channels for the rapid transportation of oxygen, Li⁺ and electrons. A thin-film and discontinuous layer of TiO₂ is coated on the CNTs surface to effectively inhibit the carbon corrosion but still could let mass transfer smoothly. Ultrafine Ru nanoparticles decorating the TiO₂/CNTs serve as efficient catalytic active sites. Benefiting from the unique structure design, Li-O₂ batteries with the cathode of TiO₂/CNTs achieve a cycling life of 110 with a fixed capacity of 500 mAh g^-1 at a current density of 100 mA g^-1. Our research generates new ideas for designing long-cycling Li-O₂ battery cathodes. LESS      Full article

Cobalt hexacyanoferrate (CoHCF) is one of the most promising cathode materials for all-climate sodium-ion batteries (SIBs) due to its open three-dimensional (3D) framework structures, high theoretical specific capacity, good voltage platform and almost no Jahn-Teller effects. However, CoHCF still suffers from poor cycling stability and bad rate capability, which is closely related to the huge distortion of frame structure and poor conductivity. In this study, by choosing nickel (Ni) to partially replace cobalt (Co) in the CoHCF lattice, we successfully prepared low-defect and Na-enriched Na₂Co_0.7Ni_0.3[Fe(CN)₆] (Co_0.7Ni_0.3HCF) in chelate and sodium salt-assisted coprecipitation method. Both experiments and first-principles calculations demonstrate that Ni substitution can effectively suppress the lattice distortion during the charging and discharging process of CoHCF. Furthermore, the introduction of Ni increases ion mobility by reducing the ion migration barrier (0.31 eV versus 0.17 eV) and improves the electronic conductivity by reducing the bandgap. It is found that Co_0.7Ni_0.3HCF exhibits superior electrochemical performance compared with that of CoHCF in a wide temperature range (-30 to 60 °C). At 25 °C, Co_0.7Ni_0.3HCF delivers a high specific capacity of 142.2 mAh g^-1 at 0.2 C, an ultrahigh rate capability with 126.2 mAh g^-1 at 5 C and excellent cycling stability with 80.9% capacity retention after 500 cycles at 5 C. Even at -30 °C,Co_0.7Ni_0.3HCF can provide a high capacity of 109 mAh g^-1 without an activation process. This work reveals the great application prospect of PBAs for all-climate SIBs, especially at low temperatures. LESS      Full article

The significant market for electric vehicles and portable electronic devices is driving the development of high-energy-density solid-state lithium batteries. However, the solid electrolyte is still the main obstacle to the development of solid-state lithium batteries, mainly due to the lack of a single solid electrolyte that is compatible with both high-voltage cathodes and lithium metal anodes. These problems can potentially be solved with multilayer electrolytes. The property of each layer of the electrolyte can be tuned separately, which not only meets the different needs of the cathode and anode but also makes up for the shortcomings of each layer of the electrolyte, thereby achieving good mechanical properties and chemical and electrochemical stability. This review first presents a brief introduction to homogeneous single-layer electrolytes. The design principles of multilayer polymer electrolytes and the application of these principles using examples from recent work are then introduced. Finally, several suggestions as guides for future work are given. LESS      Full article

Zn-based electrochemistry is considered to be the most promising alternative to Li-ion batteries due to its abundant reserves and cost-effectiveness. In addition, aqueous electrolytes are more convenient to be used in Zn-based batteries due to their good compatibility with Zn-chemistry, thereby reducing cost and improving safety. Furthermore, Zn²⁺/Zn couples involve two-electron redox chemistry, which can provide higher theoretical energy capacity and energy density. Based on this, a series of Zn-based battery systems, including Zn-ion batteries, Zn-air batteries, and Zn-based redox flow batteries, have received more and more research attention. Here, the fundamentals and recent advances in Zn-based rechargeable batteries are presented, along with perspectives on further research directions. LESS      Full article

The lithium-sulfur (Li-S) battery has been attracting much more attention in recent years due to its high theoretical capacity and low cost, although various issues, such as the “shuttle effect” and the low use ratio of active materials, have been hindering the development and application of Li-S batteries. The separator is an important part of Li-S batteries, and its modification is a simple and effective strategy to improve the electrochemical performance of Li-S batteries. In this work, we explore separators with different functions on their two sides that have been produced by a step-by-step electrospinning method. The multifunctional separator on one side is pure gelatin, and the other side is zeolitic imidazolate framework-67 (ZIF-67)-C₆₀-gelatin. The ZIF-67-C₆₀-gelatin layer on the cathode side is of great importance. The chemisorption sites on it are provided by ZIF-67, and the transformation sites of lithium polysulfide are provided by C₆₀. Gelatin, which is on the anode side, as an admirable separator material, makes the lithium flux uniform and thus prevents the generation of lithium dendrites. This type of multifunctional nanofiber separator based on double gelatin layers plays an important role in the adsorption and conversion of polysulfides, and it improves the overall performance of the Li-S battery. As a result, the Li-S batteries assembled with the prepared separator can still maintain the capacity of 888 mAh g^-1 after 100 cycles at 0.2 C, and the capacity retention rate of the Li-S batteries is 72.9% after 400 cycles at 2 C. This simple preparation method and high-performance bilayer membrane structure provide a new route for commercial application. LESS      Full article