Transition metal oxides for high performance sodium ion battery anodes

Sodium-ion batteries (SIBs) are attracting considerable attention with expectation of replacing lithium-ion batteries (LIBs) in large-scale energy storage systems (ESSs). To explore high performance anode materials for SIBs is highly desired subject to the current anode research mainly limited to carbonaceous materials. In this study, a series of transition metal oxides (TMOs) is successfully demonstrated as anodes for SIBs for the first time. The sodium uptake/extract is confirmed in the way of reversible conversion reaction. The pseudocapacitance-type behavior is also observed in the contribution of sodium capacity. For Fe2O3anode, a reversible capacity of 386 mAh g-1at 100 mA g-1 is achieved over 200 cycles; as high as 233 mAhg-1is sustained even cycling at a large current-density of 5 A g-1

RNA-seq Analysis of the BCG Vaccine in a Humanized Mouse Model

This study was aimed at screening differentially expressed genes (DEGs) and exploring the potential immune mechanism induced by the Bacillus Calmette-Guerin (BCG) vaccine in a humanized mouse model. Candidate DEGs between mice vaccinated with BCG or injected with PBS were identified through transcriptomics, and their biological functions, signaling pathways, and protein interaction networks were analyzed through bioinformatics. A total of 1035 DEGs were identified by transcriptomics: 398 up-regulated and 637 down-regulated. GO analysis indicated that these DEGs were significantly enriched in cell adhesion, oxygen transport, receptor complex, carbohydrate binding, serine-type endopeptidase activity, and peroxidase activity terms. KEGG analysis indicated that these DEGs were involved in the Rap1 signaling pathway, axon guidance, PI3K-Akt signaling pathway, natural killer cell mediated cytotoxicity, and cytokine-cytokine receptor interaction. Protein interaction network analysis demonstrated that the Myc, Vegfa, and Itgb3 proteins had the highest aggregation degree, aggregation coefficient, and connectivity. The BCG vaccine induced 1035 DEGs in humanized mice. Among them, the differentially expressed down-regulated genes myc and itgb3 involved in the PI3K-Akt signaling pathway may play essential roles in the immune mechanism of the BCG vaccine

Application of n-(Bu2)Sn(acac)2 for the deposition of nanocrystallite SnO2 films: Nucleation, growth and physical properties

Jiang Y, Sun W, Yan M, Bahlawane N. Application of n-(Bu2)Sn(acac)2 for the deposition of nanocrystallite SnO2 films: Nucleation, growth and physical properties. JOURNAL OF ALLOYS AND COMPOUNDS. 2011;509(29):7798-7802.High-quality uniform SnO2 thin films were successfully prepared by pulsed-spray evaporation chemical vapor deposition (PSE-CVD) method, using a cost-efficient precursor of (Bu2Sn)-Bu-n(acac)(2). The volatility and stability of (Bu2Sn)-Bu-n(acac)(2) were studied through thermogravimetric-differential thermal (TG-DTA) analysis and mass spectrometry, indicating the good adaptability for the CVD process. Deposition of SnO2 films was made in the range of 250-450 degrees C to investigate the effect of substrate temperature on their structural and physical properties. The film growth activation energy changes from 66.5 kJ/mol in the range of 250-330 degrees C to 0 kJ/mol at 330-450 degrees C, suggesting the change of the rate-limiting step from surface kinetics to diffusion control. All films possess the rutile-type tetragonal structure, while a change of preferred orientation from (1 1 0) to (1 0 1) plane is observed upon the increase of the deposition temperature. The different variation of the nucleation and growth rates with the deposition temperature is proposed to explain the observed unusual change of crystallite size. A significant deterioration of the electrical conductivity was observed upon the increase of the deposition temperature, which was tentatively attributed to the non-specific decomposition of the precursor at high temperature leading to carbon contamination. Optical measurements show transparencies above 80% in the visible spectral range for all films, while band gap energy increases from 4.02 eV to 4.08 eV when the deposition temperature was raised from 250 degrees C to 450 degrees C. (C) 2011 Elsevier B.V. All rights reserved

Unusual enhancement in electrical conductivity of tin oxide thin films with zinc doping

Jiang Y, Sun W, Xu B, Yan M, Bahlawane N. Unusual enhancement in electrical conductivity of tin oxide thin films with zinc doping. PHYSICAL CHEMISTRY CHEMICAL PHYSICS. 2011;13(13):5760-5763.Electrical conductivity of SnO2-based oxides is of great importance for their application as transparent conducting oxides (TCO) and gas sensors. In this paper, for the first time, an unusual enhancement in electrical conductivity was observed for SnO2 films upon zinc doping. Films with Zn/(Zn + Sn) reaching 0.48 were grown by pulsed spray-evaporation chemical vapor deposition. X-Ray diffraction (XRD) shows that pure and zinc-doped SnO2 films grow in the tetragonal rutile-type structure. Within the low doping concentration range, Zn leads to a significant decrease of the crystallite size and electrical resistivity. Increasing Zn doping concentration above Zn/(Zn + Sn) = 0.12 leads to an XRD-amorphous film with electrical resistivity below 0.015 Omega cm at room temperature. Optical measurements show transparencies above 80% in the visible spectral range for all films, and doping was shown to be efficient for the band gap tuning

Spatially-confined lithiation-delithiation in highly dense nanocomposite anodes towards advanced lithium-ion batteries

Spatially-confined electrochemical reactions are firstly realized in a highly dense nanocomposite anode for high performance lithium ion batteries. The spatially-confined lithiation-delithiation effectively avoids inter-cluster migration and perfectly retains full structural integrity. Large reversible capacity, high rate capability and superior cycling stability are achieved simultaneously. This spatially-confined lithiation-delithiation offers novel insight to enhance cycling performance of high capacity anode materials

Reversible conversion-alloying of Sb2O3 as a high-capacity, high-rate, and durable anode for sodium ion batteries

Sodium ion batteries are attracting ever-increasing attention for the applications in large/grid scale energy storage systems. However, the research on novel Na-storage electrode materials is still in its infancy, and the cycling stability, specific capacity, and rate capability of the reported electrode materials cannot satisfy the demands of practical applications. Herein, a high performance Sb2O3 anode electrochemically reacted via the reversible conversion-alloying mechanism is demonstrated for the first time. The Sb2O3 anode exhibits a high capacity of 550 mAh g-1 at 0.05 A g-1 and 265 mAh g-1 at 5 A g-1. A reversible capacity of 414 mAh g-1 at 0.5 A g-1 is achieved after 200 stable cycles. The synergistic effect involving conversion and alloying reactions promotes stabilizing the structure of the active material and accelerating the kinetics of the reaction. The mechanism may offer a well-balanced approach for sodium storage to create high capacity and cycle-stable anode materials

Conversion-Alloying Anode Materials for Sodium Ion Batteries

The past decade has witnessed a rapidly growing interest towards sodium ion battery (SIB) for large-scale energy storage in view of the abundance and easy accessibility of sodium resources. Key to addressing the remaining challenges and setbacks and to translate lab science into commercializable products is the development of high-performance anode materials. Anode materials featuring combined conversion and alloying mechanisms are one of the most attractive candidates, due to their high theoretical capacities and relatively low working voltages. In this review, the current understanding of sodium-storage mechanisms in conversion-alloying anode materials is presented. The challenges faced by these materials in SIBs, and the corresponding improvement strategies, are comprehensively discussed in correlation with the resulting electrochemical behavior. Finally, with the guidance and perspectives in this review, we create a roadmap towards the development of advanced conversion-alloying materials for commercializable SIBs

Patterns and driving factors of WUE and NUE in natural forest ecosystems along the North-South Transect of Eastern China

National Natural Science Foundation of China 30590381;National Basic Research Program of China 2010CB833504 31000211From July 2008 to August 2008, 72 leaf samples from 22 species and 81 soil samples in the nine natural forest ecosystems were collected, from north to south along the North-South Transect of Eastern China (NSTEC). Based on these samples, we studied the geographical distribution patterns of vegetable water use efficiency (WUE) and nitrogen use efficiency (NUE), and analyzed their relationship with environmental factors. The vegetable WUE and NUE were calculated through the measurement of foliar delta(13)C and C/N of predominant species, respectively. The results showed: (1) vegetable WUE, ranging from 2.13 to 28.67 mg C g(-1) H(2)O, increased linearly from south to north in the representative forest ecosystems along the NSTEC, while vegetable NUE showed an opposite trend, increasing from north to south, ranging from 12.92 to 29.60 g C g(-1) N. (2) Vegetable WUE and NUE were dominantly driven by climate and significantly affected by soil nutrient factors. Based on multiple stepwise regression analysis, mean annual temperature, soil phosphorus concentration, and soil nitrogen concentration were responding for 75.5% of the variations of WUE (p<0.001). While, mean annual precipitation and soil phosphorus concentration could explain 65.7% of the change in vegetable NUE (p<0.001). Moreover, vegetable WUE and NUE would also be seriously influenced by atmospheric nitrogen deposition in nitrogen saturated ecosystems. (3) There was a significant trade-off relationship between vegetable WUE and NUE in the typical forest ecosystems along the NSTEC (p<0.001), indicating a balanced strategy for vegetation in resource utilization in natural forest ecosystems along the NSTEC. This study suggests that global change would impact the resource use efficiency of forest ecosystems. However, vegetation could adapt to those changes by increasing the use efficiency of shortage resource while decreasing the relatively ample one. But extreme impacts, such as heavy nitrogen deposition, would break this trade-off mechanism and give a dramatic disturbance to the ecosystem biogeochemical cycle

Ever-Increasing Pseudocapacitance in RGO–MnO–RGO Sandwich Nanostructures for Ultrahigh-Rate Lithium Storage

Lithium ion batteries have attained great success in commercialization owing to their high energy density. However, the relatively delaying discharge/charge severely hinders their high power applications due to intrinsically diffusion-controlled lithium storage of the electrode. This study demonstrates an ever-increasing surface redox capacitive lithium storage originating from an unique microstructure evolution during cycling in a novel RGO–MnO–RGO sandwich nanostructure. Such surface pseudocapacitance is dynamically in equilibrium with diffusion-controlled lithium storage, thereby achieving an unprecedented rate capability (331.9 mAh g−1 at 40 A g−1, 379 mAh g−1 after 4000 cycles at 15 A g−1) with outstanding cycle stability. The dynamic combination of surface and diffusion lithium storage of electrodes might open up possibilities for designing high-power lithium ion batteries