Superior Sodium Storage of Vanadium Pentoxide Cathode with Controllable Interlamellar Spacing

Electrochemistry and Rapid Electrochromism Control of MoO3/V2O5 Hybrid Nanobilayers

MoO3/V2O5 hybrid nanobilayers are successfully prepared by the sol-gel method with a spin- coating technique followed by heat -treatment at 350 °C in order to achieve a good crystallinity. The composition, morphology, and microstructure of the nanobilayers are characterized by a scanning electron microscope (SEM) and X-ray diffractometer (XRD) that revealed the a grain size of around 20-30 nm, and belonging to the monoclinic phase. The samples show good reversibility in the cyclic voltammetry studies and exhibit an excellent response to the visible transmittance. The electrochromic (EC) window displayed an optical transmittance changes (ΔT) of 22.65% and 31.4% at 550 and 700 nm, respectively, with the rapid response time of about 8.2 s for coloration and 6.3 s for bleaching. The advantages, such as large optical transmittance changes, rapid electrochromism control speed, and excellent cycle durability, demonstrated in the electrochromic cell proves the potential application of MoO3/V2O5 hybrid nanobilayers in electrochromic devices.

Superior Sodium Storage of Carbon-Coated NaV6O15 Nanotube Cathode: Pseudocapacitance Versus Intercalation

To realize the effect of Na⁺ pseudocapacitance on the sodium storage of cathode materials, clewlike carbon-coated sodium vanadium bronze (NaV₆O₁₅) nanotubes (Na-VBNT@C) were synthesized via a facile combined sol-gel/hydrothermal method. The resultant Na-VBNT@C delivers high reversible capacities of 209 and 105 mA h g^-1 at the rates of 0.1 and 10 C, respectively. Notably, at the higher rate of 5 C (1250 mA g^-1), it can retain 94% of the initial capacity after 3000 cycles. It was found that the outstanding rate performance and the long-term cycling life of Na-VBNT@C are primarily due to the Na⁺ pseudocapacitance. Our study reveals that the design of Na⁺ pseudocapacitance is beneficial for harvesting the superior performance of NaV₆O₁₅ cathode material in sodium-ion batteries.

Synthesis and Progress of New Oxygen-Vacant Electrode Materials for High-Energy Rechargeable Battery Applications

During the last few years, a great amount of oxygen-vacant materials have been synthetized and applied as electrodes for electrochemical storage. The presence of oxygen vacancies leads to an increase in the conductivity and the diffusion coefficient; consequently, the controllable synthesis of oxygen vacancy plays an important role in improving the electrochemical performance, including achieving high specific capacitance, high power density, high energy density, and good cycling stability of the electrode materials for batteries. This review mainly focuses on research progress in the preparation of oxygen-vacant nanostructures and the application of materials with oxygen vacancies in various batteries (such as lithium-ion, lithium-oxygen, and sodium-ion batteries). Challenges related to and opportunities for oxygen-vacant materials are also provided.

Comparative Investigation of 0.5Li2MnO3·0.5LiNi0.5Co0.2Mn0.3O2 Cathode Materials Synthesized by Using Different Lithium Sources

Lithium-rich manganese-based cathode materials has been attracted enormous interests as one of the most promising candidates of cathode materials for next-generation lithium ion batteries because of its high theoretic capacity and low cost. In this study, 0.5Li₂MnO₃·0.5LiNi_0.5Co_0.2Mn_0.3O₂ materials are synthesized through a solid-state reaction by using different lithium sources, and the synthesis process and the reaction mechanism are investigated in detail. The morphology, structure, and electrochemical performances of the material synthesized by using LiOH·H₂O, Li₂CO₃, and CH₃COOLi·2H₂O have been analyzed by using Thermo gravimetric analysis (TGA), X-ray diffraction (XRD), Scanning electron microscope (SEM), Transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), and electrochemical measurements. The 0.5Li₂MnO₃·0.5LiNi_0.5Co_0.2Mn_0.3O₂ material prepared by using LiOH·H₂O displays uniform morphology with nano particle and stable layer structure so that it suppresses the first cycle irreversible reaction and structure transfer, and it delivers the best electrochemical performance. The results indicate that LiOH·H₂O is the best choice for the synthesis of the 0.5Li₂MnO₃·0.5LiNi_0.5Co_0.2Mn_0.3O₂ material.

Large interlayer spacing vanadium oxide nanotubes as cathodes for high performance sodium ion batteries

Sodium ion batteries (SIBs), as a potential alternative to Li-ion batteries (LIBs), have attracted great attention from researchers.