A hierarchical, nanoporous TiO 2 structure is successfully prepared by a simple in situ hydrolysis method. Used as an anode material, it achieves a sustained high lithium storage performance especially at high charge/discharge rates due to its substantially high surface area. The material shows two different major storage modes: a) bulk insertion, and b) pseudo-capacitive interfacial storage, which is responsible for 64% of the total capacity. In order to kinetically emphasize the interfacial storage even further, we cycle the material directly at high rates, giving 302 mA h g − 1 and 200 mA h g − 1 of fully reversible discharge capacity at charge/discharge rates of 1 C and 5 C with very high cycle stability. We propose an overall view on the different Li insertion mechanisms of the high-surface-area nanoporous TiO 2 and emphasize the importance of interfacial storage for electrode applications in Li-ion batteries.

Lithium ion batteries have become an integral part of our daily lives. Among a number of different cathode materials nickel-rich LiNi x Co y Mn z O 2 is particularly interesting. The material can deliver high capacities of ∼195 mAh g −1 putting it on the map for electric vehicles. With an increasing nickel content, a number of issues arise in the material limiting its performance. The Li/Ni mixing, highly reactive surface and formation of micro cracks are the most pressing ones. An overview of recent literature exploring these phenomena is herein summarized and were applicable solutions will be highlighted. With the advent of lithium ion batteries (LIB) in 1991 came a rapidly increasing development of consumer electronics.1,2 Soon LIB were the power source of choice for manufacturer of laptop computers and cell phones. While smart phones are getting smaller and have to operate more energy demanding applications LIB have to keep up with the pace. Cell manufactures have developed more refined ways to assemble cells leading to high energy densities of modern LIB for consumer applications. 3,4 In the meantime, scientists have developed better active materials and are constantly improving over existing ones. 5 The early LIB used lithium cobalt oxide (LCO) as cathode and graphite as anode material. LCO has a high tap density making it an ideal choice for small devices. The battery market has grown tremendously over the last 35 years and is expected to increase even more rapidly within the next years. 6 With the new market segment of electrical vehicles (EV) becoming more important every year LIB have found an additional application with a huge potential. Even though fuel cells are a natural competitor for LIB the large commitment necessary to build a hydrogen infrastructure plays into the hands of eager battery suppliers.Electrical propulsion needs battery materials with high capacities to satisfy consumer demands of a ∼500 km driving range long cycle life.4,7 Several materials have been identified as viable candidates for EVs ranging from layered mixed transition metal oxides, layered lithium rich materials and lithium sulfur batteries. [8][9][10][11] The technologically most advanced material option is layered nickel rich LiNi x Co y Mn z O 2 (NCM, x > 0.6) cathodes. The current generation of some EVs is already employing NCM523. Unfortunately, the implementation of higher nickel contents still needs to overcome a number of challenges to be viable. The review at hand will outline the development of the NCM material family with the first emphasis being on the individual endmembers LiCoO 2 , LiNiO 2 and LiMnO 2 . Problems and recent advances of these materials will be outlined. The second emphasis will be on the layered material LiNi x Co y Mn z O 2 with a focus on nickel rich materials. Problems and attempted solutions to mitigate them will be presented.= These authors contributed equally to this work.* Electrochemical Society Fellow. z E-mail: schippf@biu.ac.il Lithium Cobalt Oxide; LiCoO 2The first lithium intercal...

The interest of exploring environmentally benign and safe anode materials for lithium batteries has led to TiO 2 (anatase) nanostructures as promising candidates. However, the poor chemical diffusion of lithium in the materials still limits the rate capability. We report on the high rate capability of lithium storage with oxygen-deficient TiO 2−δ nanoparticles prepared by hydrogen reduction. A systematic study on the effect of electronic charge carrier concentration on the overall electrochemical lithium storage performance revealed that well-balanced Li + /e − transport is the key factor for high-performance TiO 2 anodes.

Polymeric dielectrics having different ratios of hydroxyl groups were intentionally synthesized to investigate the effect of hydroxyl groups on the electrical properties of pentacene-based organic thin film transistors (OTFTs). Large hysteresis usually observed in OTFT devices was confirmed to be strongly related to the hydroxyl bonds existing inside of polymeric dielectrics and could be reduced by substituting with cinnamoyl groups. Although the hydroxyl groups deteriorate the capacitance-voltage characteristics and gate leakage current densities, exceptionally high hole mobility (5.5cm2V−1s−1) could be obtained by increasing the number of hydroxyl groups, which was not caused by the improvement of pentacene crystallinity but related to the interface characteristics.

A spin-polarized vertical-cavity surface-emitting laser is demonstrated with electrical spin injection from an Fe/Al0.1Ga0.9As Schottky tunnel barrier. Laser operation with a spin-polarized current results in a maximum threshold current reduction of 11% and degree of circular polarization of 23% at 50 K. A cavity spin polarization of 16.8% is estimated from spin-dependent rate equation analysis of the observed threshold reduction.