A strategy used to design high capacity (.200 mAh g 21 ), Li 2 MnO 3 -stabilized LiMO 2 (M = Mn, Ni, Co) electrodes for lithium-ion batteries is discussed. The advantages of the Li 2 MnO 3 component and its influence on the structural stability and electrochemical properties of these layered xLi 2 MnO 3 ?(1 2 x)LiMO 2 electrodes are highlighted. Structural, chemical, electrochemical and thermal properties of xLi 2 MnO 3 ?(1 2 x)LiMO 2 electrodes are considered in the context of other commercially exploited electrode systems, such as LiCoO 2 , LiNi 0.8 Co 0.15 Al 0.05 O 2 , Li 1+x Mn 22x O 4 and LiFePO 4 . G o o d e n o u g h a t O x f o r d University, UK. After spending twenty years at the Council for Scientific and Industrial Research (CSIR), Pretoria, South Africa (1973-1994) on battery-related research, he moved to the United States where he is currently an Argonne Distinguished Fellow and Group Leader at Argonne National Laboratory outside Chicago. His primary research interest is determining the structure-electrochemical properties of solid electrolyte and electrode materials for electrochemical applications.Sun-Ho Kang received his B.S. (1992), M.S. (1994), a n d P h . D . ( 1 9 9 8 ) i n M a t e r i a l s S c i e n c e a n d Engineering from Seoul National University, South Korea. After studying as a postdoctoral fellow with P r o f e s s o r J o h n B . Goodenough at the University of Texas at Austin (1999)(2000), he joined the Chemical Engineering Division at A r g o n n e N a t i o n a l Laboratory. His primary research interests include synthesis, electrochemical and transport properties, and structure-property relationships of electrode materials for energy storage and conversion systems.

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The role of thermal spikes in energetic displacement cascades has been investigated by moleculardynamics computer simulation. For cascade energies of 3 and 5 keV in Cu, which are the highest energies (in reduced units) yet treated by fully dynamical simulations, it is found that local melting occurs and persists for several picoseconds. The implications of this behavior for atomic mixing, Frenkel-pair production, and point-defect clustering are discussed.

A systematic study of the damage function of both Ag and Cu has been performed by measuring resistivity increments induced by irradiation of thin-foil specimens at 6 K with several species of ions. Beam energies were selected such that the projectiles were stopped within the target. Results were compared with theoretical calculations based on a modified Kinchin-Pease damage function. The damage efficiency (ratio of experimental-to-theoretical values) is roughly unity for irradiations with H, but decreases rapidly as the projectile mass increases, which results in harder recoil spectra. For projectiles heavier than Ne, the efficiency becomes relatively co'nstant (0.4 for Ag and 0.35 for Cu). These results indicate that deviations from the modified Kinchin-Pease model begin to occur at energies not far above the displacement threshold energy and the eAiciency becomes roughly constant for recoil energies greater than a few keV. Comparison is made with damage-rate studies for other types of irradiation.

Li- and Mn-rich layered oxides with composition xLi2MnO3·(1 -x)LiMO2 enable high capacity and energy density Li-ion batteries, but suffer from degradation with cycling. Evidence of atomic instabilities during the first charge are addressed in this work with X-ray absorption spectroscopy, first principles simulation at the GGA+U level, and existing literature. The pristine material of composition xLi2MnO3·(1 -x)LiMn0.5Ni0.5O2 is assumed in the simulations to have the form of LiMn2 stripes, alternating with NiMn stripes, in the metal layers. The charged state is simulated by removing Li from the Li layer, relaxing the resultant system by steepest descents, then allowing the structure to evolve by molecular dynamics at 1000 K, and finally relaxing the evolved system by steepest descents. The simulations show that about ¼ of the oxygen ions in the Li2MnO3 domains are displaced from their original lattice sites, and form oxygen-oxygen bonds, which significantly lowers the energy, relative to that of the starting structure in which the oxygen sublattice is intact. An important consequence of the displacement of the oxygen is that it enables about ⅓ of the (Li2MnO3 domain) Mn ions to migrate to the delithiated Li layers. The decrease in the coordination of the Mn ions is about twice that of the Ni ions. The approximate agreement of simulated coordination number deficits for Mn and Ni following the first charge with analysis of EXAFS measurements on 0.3Li2MnO3·0.7LiMn0.5Ni0.5O2 suggests that the simulation captures significant features of the real material.

The relaxed atomic structure of a model ceramic/metal interface, 222MgO/Cu, is simulated, including lattice constant mismatch, using first principles local-density functional theory plane wave pseudopotential methods. The 399-atom computational unit cell contains 36 O and 49 Cu atoms per layer in accordance with the 7/6 ratio of MgO to Cu lattice constants. The atomic layers on both sides of the interface warp to optimize the local bonding. The interface adhesive energy is calculated. The interface electronic structure is found to vary appreciably with the local environment.