Developing advanced high‐rate electrode materials has been a crucial aspect for next‐generation lithium ion batteries (LIBs). A conventional nanoarchitecturing strategy is suggested to improve the ...rate performance of materials but inevitably brings about compromise in volumetric energy density, cost, safety, and so on. Here, micro‐size Nb14W3O44 is synthesized as a durable high‐rate anode material based on a facile and scalable solution combustion method. Aberration‐corrected scanning transmission electron microscopy reveals the existence of open and interconnected tunnels in the highly crystalline Nb14W3O44, which ensures facile Li+ diffusion even within micro‐size particles. In situ high‐energy synchrotron XRD and XANES combined with Raman spectroscopy and computational simulations clearly reveal a single‐phase solid‐solution reaction with reversible cationic redox process occurring in the NWO framework due to the low‐barrier Li+ intercalation. Therefore, the micro‐size Nb14W3O44 exhibits durable and ultrahigh rate capability, i.e., ≈130 mAh g−1 at 10 C, after 4000 cycles. Most importantly, the micro‐size Nb14W3O44 anode proves its highest practical applicability by the fabrication of a full cell incorporating with a high‐safety LiFePO4 cathode. Such a battery shows a long calendar life of over 1000 cycles and an enhanced thermal stability, which is superior than the current commercial anodes such as Li4Ti5O12.
Micro‐size Nb14W3O44 with interconnected tunnel structure is synthesized by a facile solution combustion method. Li+ insertion/extraction in Nb14W3O44 is a single‐phase solid‐solution electrochemical mechanism, leading to high Li+ diffusion coefficient and excellent structural stability during cycling. The as‐prepared Nb14W3O44 exhibits ultrahigh‐rate and high‐safety Li+ storage performance.
With the serious impact of fossil fuels on the environment and the rapid development of the global economy, the development of clean and usable energy storage devices has become one of the most ...important themes of sustainable development in the world today. Supercapacitors are a new type of green energy storage device, with high power density, long cycle life, wide temperature range, and both economic and environmental advantages. In many industries, they have enormous application prospects. Electrode materials are an important factor affecting the performance of supercapacitors. MnO2‐based materials are widely investigated for supercapacitors because of their high theoretical capacitance, good chemical stability, low cost, and environmental friendliness. To achieve high specific capacitance and high rate capability, the current best solution is to use MnO2 and carbon composite materials. Herein, MnO2–carbon composite as supercapacitor electrode materials is reviewed including the synthesis method and research status in recent years. Finally, the challenges and future development directions of an MnO2–carbon based supercapacitor are summarized.
In this paper, the mechanism of MnO2‐based supercapacitors is summarized, and the synthesis method and research status of MnO2‐carbon based supercapacitor electrode materials in recent years are reviewed. Finally, the challenges and future development directions of MnO2‐carbon based supercapacitors are discussed.
The China Spallation Neutron Source is expected to produce its first beam in 2017. Hesheng Chen and Xun-Li Wang provide an overview of this user facility and what it means for science in China and ...elsewhere. Neutron scattering is a powerful tool for materials researchers and industries. Over the years, it has made substantial contributions to many areas of physics, chemistry, biology, materials science and materials engineering. For example, neutron scattering played a crucial role in elucidating the interplay between spin uctuations and superconductivity in high-temperature superconductors1. In addition, because of their characteristic energy scales, cold neutrons are uniquely positioned to probe dynamic processes in so matter2, where applications range.
The strength of the thiol-gold interactions provides the basis to fabricate robust self-assembled monolayers for diverse applications. Investigation on the stability of thiol-gold interactions has ...thus become a hot topic. Here we use atomic force microscopy to quantify the stability of individual thiol-gold contacts formed both by isolated single thiols and in self-assembled monolayers on gold surface. Our results show that the oxidized gold surface can enhance greatly the stability of gold-thiol contacts. In addition, the shift of binding modes from a coordinate bond to a covalent bond with the change in environmental pH and interaction time has been observed experimentally. Furthermore, isolated thiol-gold contact is found to be more stable than that in self-assembled monolayers. Our findings revealed mechanisms to control the strength of thiol-gold contacts and will help guide the design of thiol-gold contacts for a variety of practical applications.
For conical indentation, the strain energy is a function of the semi-vertical cone angle, the indentation depth and the stress-strain relation. According to equivalent energy principle of ...representative volume elements (RVE) and the classical cavity assumption for material deformation region, the function with dual-parameters about volume and deformation is theoretically derived in the present study. This original equivalent-energy indentation model (EIM) is capable of forward-predicting load-depth relation and reverse-predicting uniaxial stress-strain relation for ductile materials only based on loading part of indentation. Further analyses show that the forward and reverse predicted results from EIM method are in excellent agreement with those by finite element analyses (FEA). Macro conical indentation experiments on five types of metals have been conducted using conventional indenters which are similar to Rockwell sclerometer. Consequently, the stress-strain relations predicted by EIM are quite close to those from standard tensile tests.
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Using data of online ticket sales for attractions in the seven provinces of South Central China, this study focuses on the impact of COVID-19 on tourists' destination preferences after the end of ...lockdown. Empirical results reveal that tourists' destination preferences have changed significantly, which holds under a number of robustness checks. Specifically, we find that tourists avoid traveling to destinations with more confirmed cases of COVID-19 relative to their places of origin, especially Hubei Province, and prefer destinations close to home, especially local attractions. The empirical findings have significant implications for managers and policymakers in tourism and we provide potential mechanisms for these findings based on signaling, risk perception, and prospect theory.
•Tourists' destination preferences are significantly reshaped by the COVID-19 pandemic.•Tourists less prefer destinations with more confirmed COVID-19 cases, especially Hubei Province.•Tourists more prefer destinations close to home, especially the local attractions.•Underlying mechanisms are proposed based on signaling, risk perception, and prospect theory.
Oxygen‐redox of layer‐structured metal‐oxide cathodes has drawn great attention as an effective approach to break through the bottleneck of their capacity limit. However, reversible oxygen‐redox can ...only be obtained in the high‐voltage region (usually over 3.5 V) in current metal‐oxide cathodes. Here, we realize reversible oxygen‐redox in a wide voltage range of 1.5–4.5 V in a P2‐layered Na0.7Mg0.2Fe0.2Mn0.6□0.2O2 cathode material, where intrinsic vacancies are located in transition‐metal (TM) sites and Mg‐ions are located in Na sites. Mg‐ions in the Na layer serve as “pillars” to stabilize the layered structure during electrochemical cycling, especially in the high‐voltage region. Intrinsic vacancies in the TM layer create the local configurations of “□–O–□”, “Na–O–□” and “Mg–O–□” to trigger oxygen‐redox in the whole voltage range of charge–discharge. Time‐resolved techniques demonstrate that the P2 phase is well maintained in a wide potential window range of 1.5–4.5 V even at 10 C. It is revealed that charge compensation from Mn‐ and O‐ions contributes to the whole voltage range of 1.5–4.5 V, while the redox of Fe‐ions only contributes to the high‐voltage region of 3.0–4.5 V. The orphaned electrons in the nonbonding 2p orbitals of O that point toward TM‐vacancy sites are responsible for reversible oxygen‐redox, and Mg‐ions in Na sites suppress oxygen release effectively.
Na0.7Mg0.2Fe0.2Mn0.6□0.2O2 with native transitional metal (TM) vacancies is designed as a novel cathode material for sodium‐ion batteries. The TM vacancies lead to nonbonding O 2p orbitals in this material, pointing toward these vacancies triggering reversible whole‐voltage‐range oxygen redox during charge and discharge processes. This work provides new ideals for design of cathode materials in anionic redox chemistry.
Under the rich cultural background, clothing design should effectively integrate traditional culture to provide people with better quality clothing products and meet the demands of the development of ...clothing culture. This paper analyzes the classification and application value of traditional elements and explores the expression strategies and application steps of conventional elements in clothing design. Then, we use the VGG network as the basis and combine the semantic extraction network and style migration network to extract the styling features of traditional elements, introduce the OTSU algorithm to extract the pattern features of traditional cultural elements, and combine the improved K-Means clustering algorithm to extract the main color of conventional elements. The practice of clothing design was conducted using the Republican style as a source of inspiration, and the effectiveness of the mentioned methods and the application of clothing design were evaluated and analyzed. It was found that the color purity extracted by the improved K-Means clustering algorithm was about 2.5 times higher than the result of the octree method, and the testers’ ratings of the pattern and novelty of the clothing design reached 3.81 and 4.29, respectively. The technique allows for the effective integration of traditional elements extracted based on the method into modern clothing design, promoting more diversity in the visual expression of contemporary clothing design.
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