Metal Oxides and Oxysalts as Anode Materials for Li Ion Batteries

Review on recent progress of nanostructured anode materials for Li-ion batteries

Research to develop alternative electrode materials with high energy densities in Li-ion batteries has been actively pursued to satisfy the power demands for electronic devices and hybrid electric vehicles. This critical review focuses on anode materials composed of Group IV and V elements with their composites including Ag and Mg metals as well as transition metal oxides which have been intensively investigated. This critical review is devoted mainly to their electrochemical performances and reaction mechanisms (313 references).

Li-alloy based anode materials for Li secondary batteries.

Growing market demand for portable energy storage has triggered significant research on high-capacity lithium-ion (Li-ion) battery anodes. Various elements have been utilized in innovative structures to enable these anodes, which can potentially increase the energy density and decrease the cost of Li-ion batteries. In this review, electrode and material parameters are considered in anode fabrication. The periodic table is then used to explore how the choice of anode material affects rate performance, cycle stability, Li-ion insertion/extraction potentials, voltage hysteresis, volumetric and specific capacities, and other critical parameters. Silicon (Si), germanium (Ge), and tin (Sn) anodes receive more attention in literature and in this review, but other elements, such as antimony (Sb), lead (Pb), magnesium (Mg), aluminum (Al), gallium (Ga), phosphorus (P), arsenic (As), bismuth (Bi), and zinc (Zn) are also discussed. Among conversion anodes focus is placed on oxides, nitrides, phosphides, and hydrides. Nanostructured carbon (C) receives separate consideration. Issues in high- capacity research, such as volume change, insufficient coulombic efficiency, and solid electrolyte interphase (SEI) layer stability are elucidated. Finally, advanced carbon composites utilizing carbon nanotubes (CNT), graphene, and size preserving external shells are discussed, including high mass loading (thick) electrodes and electrodes capable of providing load-bearing properties.

High‐Capacity Anode Materials for Lithium‐Ion Batteries: Choice of Elements and Structures for Active Particles

The article tells about the diversity of green spaces in London, the citizens’ attitude toward these spaces, and what Russian cities can learn from this experience.

Nature in London

This study presents a basic step toward the selection methodology of electric contact materials for microelectromechanical systems (MEMS) metal contact switches. This involves the interrelationship between two important parameters, resistivity and hardness, since they provide the guidelines and assessment of contact resistance, wear, deformation and adhesion characteristics of MEMS switches. For this purpose, thin film alloys of three noble metals, platinum (Pt), rhodium (Rh) and ruthenium (Ru) with gold (Au), were investigated. The interrelationship between resistivity and hardness was established for three levels of alloying of these metals with gold. Thin films of gold (Au), platinum (Pt), ruthenium (Rh) and rhodium (Ru) were also characterized to obtain their baseline data for comparison. All films were deposited on silicon substrates. When Ru, Rh and Pt are alloyed with Au, their hardness generally decreases but resistivity increases. This decrease or increase was, in general, dependent upon the amount of alloying.

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Characterization of metal and metal alloy films as contact materials in MEMS switches

An instrumented indentation technique was tested on three types of carbon nanotube/nanofiber-reinforced composites to investigate its applicability for measuring mechanical properties (elastic modulus and hardness). There was good agreement in the measured elastic modulus between the instrumented indentation and uniaxial tension tests for the case of a nanocomposite with a harder epoxy matrix material. In contrast, there was a considerable difference in elastic modulus between the two tests for the case of a nanocomposite with a softer polystyrene matrix material. A modified area function was then developed for the nanocomposite with the softer polystyrene matrix material, and this eliminated the difference in elastic modulus between the two test techniques. Thus, the instrumented indentation technique can be used for evaluating the mechanical properties of polymer matrix nanocomposites with an added advantage that a small sample size can be used. The instrumented indentation test was also utilized in the case of a patterned nanotube array-reinforced epoxy matrix composite. This clearly showed the modulus of the array nanocomposite improved considerably compared to that of the neat epoxy resin.

Characterization of carbon nanotube/nanofiber-reinforced polymer composites using an instrumented indentation technique

Synthesis of carbon-coated TiO2 nanotubes for high-power lithium-ion batteries

Preparation of carbon-coated TiO2 nanostructures for lithium-ion batteries

Relaxation behavior of residual stress in a shot-peened titanium alloy, Ti–6Al–4V subjected to fretting fatigue was investigated at room and elevated temperatures. Constant amplitude fretting fatigue tests were conducted at several maximum stress levels, σmax ranging from 333 to 666 MPa with a stress ratio of 0.1. Two heaters, placed at the front and back of specimen, were used to heat and maintain the temperature in the gage section of specimen at 100 and 260 °C. Residual stress was measured using the X-ray diffraction method. There was relaxation of residual compressive stress during fretting fatigue at room and elevated temperatures, which in turn manifested in the reduction of fretting fatigue life. Greater stress relaxation occurred when higher temperature, stress range and contact load were applied, however, contact load had a considerably smaller effect. Stress relaxations due to elevated temperature and mechanical load (i.e. fretting fatigue) were found to be independent processes within the test conditions of this study, such that they can be linearly superimposed to predict the total stress relaxation from fretting fatigue at elevated temperature.

Hyukjae Lee

Papers

Characterization of metal and metal alloy films as contact materials in MEMS switches

Characterization of carbon nanotube/nanofiber-reinforced polymer composites using an instrumented indentation technique

Synthesis of carbon-coated TiO2 nanotubes for high-power lithium-ion batteries

Preparation of carbon-coated TiO2 nanostructures for lithium-ion batteries

Stress relaxation behavior of shot-peened Ti–6Al–4V under fretting fatigue at elevated temperature ☆