Lithium manganese oxide (LMO), mechanochemically modified by ball-milling, is a potentially useful active material for high-power-density cathodes of lithium ion batteries. The present work investigates the electrochemical characteristic of a cathode prepared from a controlled mixture of nano-and micrometric LMO particles processed in this approach. The nanoparticles in the mixture support surface-localized insertion/extraction of Li and thus increase the cathode charge/discharge rates. The LMO microparticles promote cathode cyclability by stabilizing the coexisting nanoparticles against segregation and strong electrolyte reactions. The underlying mechanisms of these effects are studied here using voltammetry, galvanostatic cycling, Ragone plot construction, and electrochemical impedance spectroscopy. The relative timescales of charge transfer and diffusion of Li + within the LMO lattice are determined, and the criteria for material utilization during rapid charge-discharge are examined.
Nitrate, sulfate, and phosphate oxyanions are shown to serve as effective surface-modifying agents for low-pressure chemical-mechanical planarization (CMP) of Ta and TaN barrier layers of interconnect structures. The surface reactions that form the basis of this CMP strategy are investigated using cyclic voltammetry, open circuit potential and polarization resistance measurements, and impedance spectroscopy. The results suggest that forming structurally weak layers of surface oxides is crucial to chemically controlling the CMP of Ta/TaN at low polish-pressures. It is shown that in oxyanion-based slurries, this can be accomplished by modifying the sample surfaces with anionincorporated oxide films of Ta or TaN, which, in turn, can readily be removed with moderate abrasion. Electrochemical results elaborate the reaction mechanisms that lead to anion-modified oxides, such as Ta 2 O 5(1
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