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Islam M.S.,University of Bath | Fisher C.A.J.,Japan Fine Ceramics Center
Chemical Society Reviews | Year: 2014

Energy storage technologies are critical in addressing the global challenge of clean sustainable energy. Major advances in rechargeable batteries for portable electronics, electric vehicles and large-scale grid storage will depend on the discovery and exploitation of new high performance materials, which requires a greater fundamental understanding of their properties on the atomic and nanoscopic scales. This review describes some of the exciting progress being made in this area through use of computer simulation techniques, focusing primarily on positive electrode (cathode) materials for lithium-ion batteries, but also including a timely overview of the growing area of new cathode materials for sodium-ion batteries. In general, two main types of technique have been employed, namely electronic structure methods based on density functional theory, and atomistic potentials-based methods. A major theme of much computational work has been the significant synergy with experimental studies. The scope of contemporary work is highlighted by studies of a broad range of topical materials encompassing layered, spinel and polyanionic framework compounds such as LiCoO2, LiMn2O4 and LiFePO4 respectively. Fundamental features important to cathode performance are examined, including voltage trends, ion diffusion paths and dimensionalities, intrinsic defect chemistry, and surface properties of nanostructures. © 2014 The Royal Society of Chemistry.

Fisher C.A.J.,Japan Fine Ceramics Center | Kuganathan N.,University of Bath | Islam M.S.,University of Bath
Journal of Materials Chemistry A | Year: 2013

The search for new low-cost and safe cathodes for next-generation lithium batteries has led to increasing interest in silicate materials. Here, a systematic comparison of crystal properties, defect chemistry and Li-ion migration behaviour of four polymorphs of Li2MnSiO4 is reported based on the results of atomistic simulations. The four polymorphs examined have Pmn21, Pmnb, P21/n, and Pn symmetry. Lattice energies of all four polymorphs are very similar, with only a small energy preference for the two orthorhombic phases over the monoclinic phases, which explains the difficulty experimentalists have had preparing pure-phase samples. Defect formation energies of the polymorphs are also similar, with antisite Li/Mn defects the most energetically favourable. Detailed analysis of the Li-ion migration energy surfaces reveals high activation energies (around 0.9 to 1.7 eV) and curved trajectories. All four polymorphs are thus expected to be poor Li-ion conductors, requiring synthesis as nanoparticles to facilitate sufficient Li transfer. The results accord well with experimental reports on the structure, relative phase stabilities and electrochemical performance of materials in this system. © The Royal Society of Chemistry 2013.

Malavasi L.,CNR Institute for Energetics and Interphases | Fisher C.A.J.,Japan Fine Ceramics Center | Islam M.S.,University of Bath
Chemical Society Reviews | Year: 2010

This critical review presents an overview of the various classes of oxide materials exhibiting fast oxide-ion or proton conductivity for use as solid electrolytes in clean energy applications such as solid oxide fuel cells. Emphasis is placed on the relationship between structural and mechanistic features of the crystalline materials and their ion conduction properties. After describing well-established classes such as fluorite- and perovskite-based oxides, new materials and structure-types are presented. These include a variety of molybdate, gallate, apatite silicate/germanate and niobate systems, many of which contain flexible structural networks, and exhibit different defect properties and transport mechanisms to the conventional materials. It is concluded that the rich chemistry of these important systems provides diverse possibilities for developing superior ionic conductors for use as solid electrolytes in fuel cells and related applications. In most cases, a greater atomic-level understanding of the structures, defects and conduction mechanisms is achieved through a combination of experimental and computational techniques (217 references). © 2010 The Royal Society of Chemistry.

Japan Fine Ceramics Center and Kabushiki Kaisha Toyota Jidoshokki | Date: 2014-03-19

This invention is a sunlight-to-heat converting member containing chromium silicide having an element ratio of Cr to Si from 1:1.6 to 1:4.7. This invention is also a sunlight-to-heat converting stack including a layer of the sunlight-to-heat converting member and a metal layer. This invention is also a sunlight-to-heat converting device including a light collecting part, either or both of a container and a flow path where sunlight is collected by the light collecting part, and a heating medium housed in either or both of the container and the flow path. The sunlight-to-heat converting member or the sunlight-to-heat converting stack is formed on a surface of either or both of the container and the flow path. The sunlight-to-heat converting member, the sunlight-to-heat converting stack, and the sunlight-to-heat converting device of this invention can convert light to heat efficiently.

Kabushiki Kaisha Toyota Jidoshokki and Japan Fine Ceramics Center | Date: 2013-10-11

The present invention addresses the problem of providing a heat conversion member capable of efficiently converting light to heat. This heat conversion member is characterized in that it includes a composite material of at least one type of semiconductor and at least one type of metal material.

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