Hello, A yearly allocation for the LCRC cluster has been requested with the following updated information: Submitter/PI: Roy Benedek Project Name: Dissolution Division: CSE Project title: Dynamical simulation of lithium manganate spinel dissolution in acid Associated funding: Office of FreedomCar and Vehicle Technologies (Batteries for Advanced Transportation Technologies (BATT) Program), U. S. Dept. of Energy Other Systems: NERSC Science: The acid-promoted dissolution of lithium manganate, LiMn2O4, is an obstacle to its application as a cathode material in lithium-ion batteries. Although dissolution-inhibition strategies are available (such as coating the surface with a thin protective layer), a better fundamental understanding of the dissolution process would help focus battery-design efforts. Project description: In work described in the Progress Report, first principles MD simulations have suggested two mechanisms by which acid anions (fluorine in the case of HF), promote the dissolution of Mn ions from the surface of the lithium-ion-battery cathode, lithium manganate. First, F ions in the acid adsorb to Mn ions at the surface of LiMn2O4. The strong chemical bond between a surface Mn and the adsorbate weakens the bonds between the Mn and the substrate O ions bound to it, by virtue of the bond-order conservation principle. Second, as the Mn-F complex detaches from the substrate, electron charge transfer from the substrate reduces the Mn ion from its initial trivalent state before dissolution to a divalent state, its equilibrium state in aqueous solution. After the Mn ion is reduced, its attraction to the substrate, and the probability of reattachment, is greatly diminished. In neutral water, electron transfer, and reduction of the trivalent Mn, also occurs as it detaches from the substrate, but only and a greater distance, and not as readily, as in the acidic medium. Thus, the dissolution is greatly enhanced in acid. Work in the next FY will be directed at corroborating and confirming the generality of the mechanisms proposed above for the enhancement of LiMn2O4 spinel dissolution by acid. The simulations that suggested the above mechanism were based on dissolution of Mn from (110) surfaces to which the Mn ions were three-fold coordinated. More commonly, surface Mn occurs in four-fold coordinated sites, and therefore, we would like to confirm that qualitatively similar behavior applies in the case of dissolution of four-fold-coordinate Mn ions at lithium manganate surfaces. Simulations will be performed of Mn ion dissolution at four-fold coordinated sites at (001) surfaces. Our simulations up to now have been limited to room temperature (actually 375K, as mentioned in the Progress Report). We intend to perform simulations at at temperature 75K higher to explore how temperature influences the dissolution process. According to our interpretation, another aspect of the enhancement of spinel dissolution by acid is the weakening of Mn bonding with the substrate, attributed to bond-order conservation effects in the presence of strong bonding of F ions to surface Mn. Small cluster calculations will be performed to elucidate on a simple system the bond-weakening effect of F adsorption to spinel. Project URL: Current FY Hours Used: undetermined amount New FY Requested allocation: 60000 Q1: 15000 Q2: 15000 Q3: 15000 Q4: 15000 Justification: Thank You, The LCRC Accounts System