SciCombinator

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Concept: Lithium-ion batteries

169

We demonstrate a simple, efficient, yet versatile strategy for the synthesis of novel hierarchical heterostructures composed of TiO(2) nanofiber stem and various metal oxides (MOs) secondary nanostructures, including Co(3)O(4), Fe(2)O(3), Fe(3)O(4), and CuO, by advantageously combining the versatility of the electrospinning technique and hydrothermal growth method, for which the controllable formation process and possible formation mechanism are also investigated. Moreover, as a proof-of-concept demonstration of the functional properties of these hierarchical heterostructures, the Co(3)O(4)/TiO(2) hierarchical heterostructures are investigated as the lithium-ion batteries (LIBs) anode materials for the first time, which not only delivers a high reversible capacity of 632.5 mAh g(-1) and 95.3% capacity retention over 480 cycles, but also shows excellent rate capability with respect to the pristine TiO(2) nanofibers. The synergetic effect between Co(3)O(4) and TiO(2) as well as the unique feature of hierarchical heterostructures are probably responsible for the enhanced electrochemical performance.

Concepts: Electric car, Lithium-ion batteries, Lithium-ion polymer battery, Lithium-ion battery, Battery, Lithium battery, Rechargeable battery, Lithium

27

Watch your figure: Three different shapes of TiO2 nanoparticles with various exposed facets have been synthesized by changing the adsorbents. The spindly octahedron with exposed high-index {401} facet exhibit the highest electrochemical performance than that of the other shapes.

Concepts: Lithium-ion batteries, Lithium-ion polymer battery, Titanium dioxide, Facet, Octahedron, Lithium-ion battery, Diamond, Rechargeable battery

27

A rapid and controllable route is developed for the synthesis of MnO nanoparticles that are encapsulated uniformly in three-dimensional (3D) mesoporous interconnected carbon networks (MnO-MICN) through an efficient microwave-polyol process combined with a subsequent thermal treatment. The dependence of sodium citrate on the morphology of the Mn-based precursors was investigated systematically. Results show that the unique mesoporous interconnected carbon network (MICN) can not only buffer the large volume expansion of MnO during the electrochemical cycling, but also improve the electrode/electrolyte contact area, favoring the fast Li-ion transport and high specific capacity, superior cyclability, and excellent rate capability. When evaluated as an anode material for lithium-ion batteries, the as-formed 3D MnO-MICN nanocomposite exhibits a highly reversible capacity of 1224 mAh g-1 with a Coulombic efficiency of ~99% at a current density of 200 mA g-1 over 200 cycles.

Concepts: Volume, Electric car, Lithium-ion batteries, Lithium-ion polymer battery, Battery, Lithium-ion battery, Rechargeable battery, Lithium

27

In the present work, the nanocomposite of MoO2-ordered mesoporous carbon (MoO2-OMC) was synthesized for the first time by using a carbon thermal reduction route and the mesoporous carbon as the nano-reactor. The synthesized nanocomposite was characterized by XRD, TG, N2 adsorption-desorption, SEM and TEM measurements. Furthermore, this nanocomposite was used as an anode material for Li-ion intercalation and exhibited large reversible capacity, high rate performance and good cycling stability. For instance, a high reversible capacity of 689 mAh g-1 can be remained after 50 cycles at a current density of 50 mA g-1. It is worth mentioning that the MoO2-OMC nanocomposite electrode can attain a high reversible capacity of 401 mAh g-1 at a current density as high as 2 A g-1. These results might be contributed to the intrinsic characteristics of nanocomposite, which offered a better accommodation of the strain and volume changes and a shorter path for Li-ion and electron transport, leading to the improved capacity and enhanced rate capability.

Concepts: Lithium-ion batteries, Lithium-ion polymer battery, Lithium, Volume, Lithium-ion battery, Time, Rechargeable battery, Battery

27

Uniform Li(4) Ti(5) O(12) hollow spheres with mesoporous shells of tuneable thickness have been synthesized by an efficient templating approach. Owing to the unique hollow structure and highly mesoporous framework, these Li(4) Ti(5) O(12) hollow spheres exhibit remarkable high-rate performance and long-term cycling stability when evaluated as anode materials for lithium-ion batteries.

Concepts: Lithium-ion batteries, Nanowire battery, Lithium-ion polymer battery, Lithium battery, Lithium, Lithium-ion battery

27

Binary transition metal oxides have been attracting extensive attention as promising anode materials for lithium-ion batteries, due to their high theoretical specific capacity, superior rate performance and good cycling stability. Here, loaf-like ZnMn(2)O(4) nanorods with diameters of 80-150 nm and lengths of several micrometers are successfully synthesized by annealing MnOOH nanorods and Zn(OH)(2) powders at 700 °C for 2 h. The electrochemical properties of the loaf-like ZnMn(2)O(4) nanorods as an anode material are investigated in terms of their reversible capacity, and cycling performance for lithium ion batteries. The loaf-like ZnMn(2)O(4) nanorods exhibit a reversible capacity of 517 mA h g(-1) at a current density of 500 mA g(-1) after 100 cycles. The reversible capacity of the nanorods still could be kept at 457 mA h g(-1) even at 1000 mA g(-1). The improved electrochemical performance can be ascribed to the one-dimensional shape and the porous structure of the loaf-like ZnMn(2)O(4) nanorods, which offers the electrode convenient electron transport pathways and sufficient void spaces to tolerate the volume change during the Li(+) intercalation. These results suggest the promising potential of the loaf-like ZnMn(2)O(4) nanorods in lithium-ion batteries.

Concepts: Nanowire battery, Lithium-ion batteries, Lithium battery, Electric car, Lithium-ion polymer battery, Lithium, Rechargeable battery, Lithium-ion battery

27

Hollow 0.3Li(2)MnO(3)·0.7LiNi(0.5)Mn(0.5)O(2) microspheres are synthesized on a large scale through a simple in situ template-sacrificial route. Starting from porous MnO(2) microspheres, the hollow microspheres assembled with 0.3Li(2)MnO(3)·0.7LiNi(0.5)Mn(0.5)O(2) nanocrystals are formed by a nanoscale Kirkendall effect. The nanocrystal-assembled hollow 0.3Li(2)MnO(3)·0.7LiNi(0.5)Mn(0.5)O(2) microspheres exhibit a highly reversible capacity as high as 295 mAh g(-1) over 100 cycles and excellent rate capability (125 mAh g(-1) at 1000 mA g(-1)). Benefitting from a unique hollow and nanocrystalline architecture, the as-formed hollow microspheres show much enhanced high-temperature (55 °C) electrochemical performances, compared with the products obtained by conventional sol-gel/solid-state reaction methods. This work demonstrates that a fabrication strategy based on the present in situ template-sacrificial approach offers a new method for the design of high-performance cathode materials with hollow interiors for Li-ion battery applications.

Concepts: Lithium-ion batteries, Lithium-ion polymer battery, Electric car, Lithium iron phosphate battery, Lithium-ion battery, Lithium battery, Lithium, Rechargeable battery

27

We report a facile ‘one-pot’ method for the synthesis of Sn embedded carbon-silica (CS) mesostructured (nanostructured) composites through the selective interaction of resol (carbon precursor), tetraethylorthosilicate (TEOS), and tributylphenyltin (Sn precursor) with an amphiphilic diblock copolymer, poly (ethylene oxide-b-styrene), PEO-b-PS. A unique morphology transition from Sn nanowires to spherical Sn nanoparticles embedded in CS framework has been obtained. Metallic Sn species are homogeneously embedded in a rigid CS framework and are effectively confined within the nanostructures. The resulting composites are used as anode materials for lithium-ion batteries and exhibit high specific capacities (600 mA h g -1 at a current density of 45 mA g-1, 440 mA h g-1 at a current density of 300 mA g-1) and an excellent cyclability of over 100 cycles with high coulombic efficiency. Most of all, the novel method developed in this work for synthesizing functional hybrid materials can be extended to the preparation of various functional nanocomposites owing to its versatility and facileness.

Concepts: Nanowire battery, Lithium-ion batteries, Electric car, Lithium battery, Lithium-ion polymer battery, Rechargeable battery, Lithium-ion battery, Lithium

27

A facile, environmentally friendly, and economical synthetic route for production of large-amounts (gram scale) of two-dimensional (2D) layered SnS(2) nanoplates is presented. The electrode fabricated from the SnS(2) nanoplate exhibits excellent lithium-ion battery performance with highly reversible capacity, good cycling stability and excellent capacity retention after 30 cycles.

Concepts: Electric car, Lithium-ion batteries, Lithium-ion polymer battery, Lithium-ion battery, Lithium, Lithium battery, Rechargeable battery

22

Lithium-ion battery fires generate intense heat and considerable amounts of gas and smoke. Although the emission of toxic gases can be a larger threat than the heat, the knowledge of such emissions is limited. This paper presents quantitative measurements of heat release and fluoride gas emissions during battery fires for seven different types of commercial lithium-ion batteries. The results have been validated using two independent measurement techniques and show that large amounts of hydrogen fluoride (HF) may be generated, ranging between 20 and 200 mg/Wh of nominal battery energy capacity. In addition, 15-22 mg/Wh of another potentially toxic gas, phosphoryl fluoride (POF3), was measured in some of the fire tests. Gas emissions when using water mist as extinguishing agent were also investigated. Fluoride gas emission can pose a serious toxic threat and the results are crucial findings for risk assessment and management, especially for large Li-ion battery packs.

Concepts: Lithium-ion batteries, Lithium-ion polymer battery, Electric car, Lithium-ion battery, Lithium battery, Rechargeable battery, Lithium