Hello, A yearly allocation for the LCRC cluster has been requested with the following updated information: Submitter/PI: hakim iddir Project Name: MBM_CEES2 Division: MSD Project title: Modeling Battery Materials CEES2 Associated funding: DOE, EFRC Other Systems: PNNL Science: As a part of continuing effort to contribute to the battery research here at Argonne, and to the EFRC (CEES II) project. We will perform theoretical work based on density functional theory using “VASP”, to simulate the equilibrium particle shapes of non-stoichiometric and doped LiMn2O4 particles. As stated in the CEES II proposal, it is central to this task to understand the electrode structure instabilities induced electrochemically. LiMn2O4 is ideal as a high-capacity Li-ion battery cathode material by virtue of its low toxicity, low cost, and the high natural abundance of Mn. However, this material suffers from Mn dissolution problem that not only induces a capacity fade [1], but can also poison the anode. The dissolution is associated with the disproportionation of Mn3+, and is dependent on the surface structure, hence the crystal orientation as well [2, 3]. For example, (111) is expected to be more stable as the reconstruction moves Mn to the surface sub-la yers[4]. Previous works show that (111) surface is more stable than (100) and (110) surfaces with respect to Mn dissolution [3, 5]. To improve its stability with respect to Mn dissolution, one would like to predict the synthesis conditions that would preferentially enhance the (111) surface ratio over that of the other facets, not only in pristine stoichiometric state, but also non-stoichiometric and doped surfaces. However, it is also known that (111) is not favorable for Li diffusion, hence reducing the rate capability [3]. A truncated cubo-octahedron was proposed as a good compromise between stability and rate capability[3]. Karim et al. determined the equilibrium particle shape of pure stoichiometric LiMn2O4 particles, in which they predicted a stable reconstructed (111) facet [4], in agreement with the observed shapes at high temperatures for Li1+xMn2-xO4 (x=0.125)[6]. However, several experimental results show that the particle shapes obtained do not all exhibit the predicted shape by the model. This discrepancy could be due to the nature and stoichiometry of the different surfaces, which depend on the experimental conditions the particles were synthesized in. In this work we will investigate the particles shape for non-stoichiometric as well as with dopants, with the goal being an optimized particle shape that will provide both stability and good rate capability. A second focus will be on investigation of the effect of the support and hence the interface/strain of epitaxial thin films of LiMn2O4 grown on single crystals, such as SrTiO3 and MgO for three crystallographic orientations (111) (100) and (110). Here we will focus on the interplay between Jahn-Teller distortion, Mn dissolution and Strain. This work is in line with the two of the DOE Basic Research Needs Report on Electrical Energy Storage: • Rational design of interfaces and interphases in chemical energy storage. • Novel designs and strategies for electrochemical systems. References: 1. Tarascon, J.M. and D. Guyomard, Li Metal‐Free Rechargeable Batteries Based on Li1 + x Mn2 O 4 Cathodes ( 0 ≤ x ≤ 1 ) and Carbon Anodes. Journal of The Electrochemical Society, 1991. 138(10): p. 2864-2868. 2. Hirayama, M., et al., Dynamic Structural Changes at LiMn2O4/Electrolyte Interface during Lithium Battery Reaction. Journal of the American Chemical Society, 2010. 132(43): p. 15268-15276. 3. Kim, J.-S., et al., A Truncated Manganese Spinel Cathode for Excellent Power and Lifetime in Lithium-Ion Batteries. Nano Letters, 2012. 12(12): p. 6358-6365. 4. Karim, A., S. Fosse, and K.A. Persson, Surface structure and equilibrium particle shape of the LiMn2O4 spinel from first-principles calculations. Physical Review B, 2013. 87(7): p. 075322. 5. Thackeray, M.M., Manganese oxides for lithium batteries. Progress in Solid State Chemistry, 1997. 25(1–2): p. 1-71. 6. Takada, T., et al., Structure and electrochemical characterization of Li1+xMn2−xO4 spinels for rechargeable lithium batteries. Journal of Power Sources, 1999. 81–82(0): p. 505-509. Project description: In the second phase of this project we will perform theoretical work based on density functional theory using “VASP”, to investigate the effect of dopants on the electronic structure of low index surfaces of LiMn2O4, such as (100), (110) and the reconstructed (111). The goal from this work is to establish a correlation between the electronic structure of the doped surfaces and their stability with respect to Mn dissolution. Several dopants, concentrations and distributions will be considered. A second part of this work will also focus on the interaction of these surfaces with specific probe molecules that will be used to establish trends with respect to surface stability and Mn dissolution. Total energy calculations will be performed for different LiMn2O4 surfaces and compositions, in which Mn will be substituted with other candidate transition metals such as Ni, Co, Al, and Ti. This will require total energy calculations of surfaces (slab geometry) as well as corresponding surface compositions (surface segregation). A second focus will be on investigation of the effect of the dopants on the surface electronic and reactivity properties of LMO and doped LMO (LMM’O). Two different probe molecules (NH3, HCL) will be used on two low-index LMO and LMM’O surfaces. Several configurations of these molecules will be needed to establish the lowest energy conformations. Industry partnership: Project URL: Current FY Hours Used: undetermined amount New FY Requested allocation: 900000 Q1: 250000 Q2: 250000 Q3: 200000 Q4: 200000 Justification: Ab-initio MD as well as DFT calculations were optimized on Fusion/Blues. Storage requirements: Thank You, The LCRC Accounts System