Energy-storage technologies, including electrical double-layer capacitors and rechargeable batteries, have attracted significant attention for applications in portable electronic devices, electric vehicles, bulk electricity storage at power stations, and "load leveling" of renewable sources, such as solar energy and wind power. Transforming lithium batteries and electric double-layer capacitors requires a step change in the science underpinning these devices, including the discovery of new materials, new electrochemistry, and an increased understanding of the processes on which the devices depend. The Review will consider some of the current scientific issues underpinning lithium batteries and electric double-layer capacitors.

In the past decade, there have been exciting developments in the fi eld of lithium ion batteries as energy storage devices, resulting in the application of lithium ion batteries in areas ranging from small portable electric devices to large power systems such as hybrid electric vehicles. However, the maximum energy density of current lithium ion batteries having topatactic chemistry is not suffi cient to meet the demands of new markets in such areas as electric vehicles. Therefore, new electrochemical systems with higher energy densities are being sought, and metal-air batteries with conversion chemistry are considered a promising candidate. More recently, promising electrochemical performance has driven much research interest in Li-air and Zn-air batteries. This review provides an overview of the fundamentals and recent progress in the area of Li-air and Zn-air batteries, with the aim of providing a better understanding of the new electrochemical systems.

High energy-density lithium-ion batteries are in demand for portable electronic devices and electrical vehicles. Since the energy density of the batteries relies heavily on the cathode material used, major research efforts have been made to develop alternative cathode materials with a higher degree of lithium utilization and specific energy density. In particular, layered, Ni-rich, lithium transition-metal oxides can deliver higher capacity at lower cost than the conventional LiCoO2 . However, for these Ni-rich compounds there are still several problems associated with their cycle life, thermal stability, and safety. Herein the performance enhancement of Ni-rich cathode materials through structure tuning or interface engineering is summarized. The underlying mechanisms and remaining challenges will also be discussed.

We present Si nanotubes prepared by reductive decomposition of a silicon precursor in an alumina template and etching. These nanotubes show impressive results, which shows very high reversible charge capacity of 3247 mA h/g with Coulombic efficiency of 89%, and also demonstrate superior capacity retention even at 5C rate (=15 A/g). Furthermore, the capacity in a Li-ion full cell consisting of a cathode of LiCoO2 and anode of Si nanotubes demonstrates a 10 times higher capacity than commercially available graphite even after 200 cycles.

MoS(2) nanoplates, consisting of disordered graphene-like layers, with a thickness of ∼30 nm were prepared by a simple, scalable, one-pot reaction using Mo(CO)(6) and S in an autoclave. The product has a interlayer distance of 0.69 nm, which is much larger than its bulk counterpart (0.62 nm). This expanded interlater distance and disordered graphene-like morphology led to an excellent rate capability even at a 50C (53.1 A/g) rate, showing a reversible capacity of 700 mAh/g. In addition, a full cell (LiCoO(2)/MoS(2)) test result also demonstrates excellent capacity retention up to 60 cycles.

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Electrode designs, which can accommodate severe volume changes (ca. 400 %) of silicon anode materials upon lithium insertion, are the main prerequisite for high-performance lithium ion batteries. Among various techniques investigated for this purpose, a robust polymeric binder is a promising means to inhibit mechanical fracture of silicon negative electrodes during cycling.Lithium ion batteries (LIBs) are one of the most promising energy storage devices owing to their high power and energy densities. [1] For LIBs, silicon is a promising candidate anode material owing to its high theoretical specific capacity of 4200 mAh g À1 for Li 4.4 Si, low electrochemical potential between 0 and 0.4 V versus Li/Li + , and small initial irreversible capacity compared with other metal-or alloy-based anode materials. [2] Nevertheless, the practical application of silicon to LIBs is still quite challenging because silicon suffers from severe volume changes (ca. 400 %) during Li + insertion and extraction processes, which breaks electrical contact between the silicon particles and results in degradation of electrodes and rapid capacity loss. [3] To alleviate volume change, silicon nanoparticles and porous silicon materials have been extensively studied because the smaller particles undergo smaller absolute volume change. [4] The aggregation of silicon particles upon cycling, however, accelerates the degradation of electrodes. Thus, many efforts have focused on the synthesis of silicon-carbon composites to prevent the agglomeration of silicon, resulting in a highly improved cycle performance. [5] Although remarkable improvements in the electrochemical performance of silicon-based anodes have been achieved, electrode deformation and external cell expansion still occur because of the inherent volume change of silicon. This large cell volume change is the main factor limiting the commercialization of silicon-based anode materials.

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