The lithium-oxygen battery, of much interest because of its very high-energy density, presents many challenges, one of which is a high-charge overpotential that results in large inefficiencies. Here we report a cathode architecture based on nanoscale components that results in a dramatic reduction in charge overpotential to B0.2 V. The cathode utilizes atomic layer deposition of palladium nanoparticles on a carbon surface with an alumina coating for passivation of carbon defect sites. The low charge potential is enabled by the combination of palladium nanoparticles attached to the carbon cathode surface, a nanocrystalline form of lithium peroxide with grain boundaries, and the alumina coating preventing electrolyte decomposition on carbon. High-resolution transmission electron microscopy provides evidence for the nanocrystalline form of lithium peroxide. The new cathode material architecture provides the basis for future development of lithium-oxygen cathode materials that can be used to improve the efficiency and to extend cycle life.

This is the accepted version of the paper.This version of the publication may differ from the final published version. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 2 Rechargeable lithium ion batteries (LIBs) have long been considered as the most effective energy-storage technology and dominated portable electronic market for over two decades. Permanent repository link1, 2 Based on the intercalation mechanism, state-of-the-art Li-ion technology can exhibit a theoretical specific energy of ~400 Wh/kg, such as LiCoO 2 /graphite system. 3 However, it is urgent to explore new chemistries and materials that can significantly increase the cell energy density, considering the future demand for electronic vehicles and large-scale energy storage plants. 4,5 Graphite, a widely used anode material for the current LIBs, has a theoretical capacity of only 372 mAh/g, given a fully intercalated LiC 6 compound, which is one of the limiting factors for achieving high energy density of the cell 6 . In order to overcome such technical bottleneck, considerable effort has been devoted to design and synthesise new anode materials with higher theoretical specific capacity, such as transition metal oxides (SnO 2 , Co 3 O 4 ,Fe 3 O 4 ), Sn and Si 7 . However, all these materials suffer from severe volume variation during charge-discharge cycling, which results in serious pulverisation of the electrodes, and thus, rapid capacity degradation. For instance, Si has a high specific capacity of 4200 mAh/g if fully lithiated to Li 4.4 Si, however, it also shows a large volume expansion up to 400%. Such volume expansion causes huge mechanical stress of the electrode, and therefore, severely limits the lifetime of Si anode. Although various strategies have been proposed to enhance the structural stability of Si-based materials, including carbon or polymer coating 8,9 , nano-structuring 10-12 and hierarchical hybridization, [13][14][15] it is still very challenge to overcome the issue of the inherent volume change of these materials during cycling.Transition metal dichalcogenides (TMD) MX 2 (M=Mo, Ti, V, and W, X=S or Se) 16,17 with the similar feature of layered structure as graphite could have great potential for alternative anode materials. In general, MX 2 has strong covalent bonds within layers and weak Van der Waals forces between layers, which provide ideal space for intercalation of lithium ions. For instance, MoS 2 has much larger spacing between neighboring layers (0.615 nm) than that of graphite (0.335 nm) and weak van der Waals forces between the layers, which, in principal, may make the Li + diffuse easier. However, certain electrochemical properties of MX 2 can only be achieved in their 1-D or 2-D nanostructured crystals because of the relatively high resistance for Li-ion transport in their bulk form. In addition, the electron conductivity of th...

Since the introduction about 30 years ago, CE techniques have gained a significant impact in pharmaceutical analysis. The present review covers recent advances and applications of CE for the analysis of pharmaceuticals. Both small molecules and biomolecules such as proteins are considered. The applications range from the determination of drug-related substances to the analysis of counterions and the determination of physicochemical parameters. Furthermore, general considerations of CE methods in pharmaceutical analysis are described.

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