Hello, A new project on the LCRC cluster has been requested. Please forward the information on to the LCRC Allocation sub-committee. Applicant's name: hakim iddir Applicant's institution: ANL Applicant's division: MSD Project Name: MEA Project title: Modeling Electrolyte Additives Associated funding: EERE Other Systems: Science: Nickel-rich layered oxide cathode materials have seen widespread deployment due to their high gravimetric capacity and high average discharge voltage. However, achieving this high capacity requires charging voltages above the potential at which the electrolytes decompose at the cathode surface (>4.5 V vs. Li/Li+), which leads to impedance rise and capacity loss. One strategy to stabilize this interface is by the use of electrolyte additives that, in small amounts, can change the chemical interactions at the interface and favorably affect the surface stability. Knowledge of the cathode-electrolyte interactions is necessary to better understand the degradation and action mechanism of such additives. Project description: Within the High Energy High Voltage (HEHV) project we have undertaken a multi-pronged approach to understand the chemical reaction mechanisms of a family of structurally related phosphates and phosphites on the surface of a charged LiNi0.5Mn0.3Co0.2 cathodes, as well as their effect on cell performance. Our approach includes electrochemical and mechanistic evaluation, characterization, and theoretical simulations with phosphorus-based additives. We will use Density Functional Theory (DFT) in order to elucidate the mechanism of reaction of electrolyte molecules on Li(Ni1-x-yMnxCoy)O2 (NMC) surfaces. We have determined so far the first oxidation steps of select alkyl carbonate electrolyte species. We also used Ab Initio Molecular Dynamics (AIMD) to explore possible adsorption configurations of several phosphite and phosphate molecules on the most reactive NMC surfaces; and computed the relative stability of different additives and their derivatives on NMC surfaces. At high states of charge, we found different reactive pathways depending on additive characteristics such as the size of the functional groups in the phosphite molecule and the degree of decomposition of such species.1,2 These studies provide some insights into the mechanism of phosphite additive oxidation on the cathode. We plan on continuing this study using several new functional group and different NMC facets. In this project we propose to check several combinations of alkane groups and silyl groups and also transesterification products of the additives with the alkyl-carbonates solvent molecules. This account for at least 12 different additive molecules. We estimate at least four reaction steps for each possible pathway. Considering two different pathways on two different surfaces, we have to compute 192 adsorption energies. Since each surface slab have about 250 atoms, we will need at least 2000 computer hours per calculation. Several initial molecule/surface configurations are needed to determine the lowest energy state. This would account for 600000 computer hours. We also will compute the energy barriers for the most thermodynamic favorable transformations in the surface of the cathode. We will use the Nudged Elastic Band (NEB) method to accomplish these calculations. These calculations would require approximately 200000 computer hours. A total of 800000 computer hours would b e needed to accomplish the proposed project. References (1) Peebles, C.; Sahore, R.; Gilbert, J. A.; Garcia, J. C.; Tornheim, A.; Bareño, J.; Iddir, H.; Liao, C.; Abraham, D. P. Tris(Trimethylsilyl) Phosphite (TMSPi) and Triethyl Phosphite (TEPi) as Electrolyte Additives for Lithium Ion Batteries: Mechanistic Insights into Differences during LiNi0.5Mn0.3Co0.2O2-Graphite Full Cell Cycling. J. Electrochem. Soc. 2017, 164 (7), A1579–A1586. (2) Tornheim, A.; Peebles, C.; Gilbert, J. A.; Sahore, R.; Garcia, J. C.; Bareño, J.; Iddir, H.; Liao, C.; Abraham, D. P. Evaluating Electrolyte Additives for Lithium-Ion Cells: A New Figure of Merit Approach. J. Power Sources 2017, 365, 201–209. Industry partnership: Project URL: Requested allocation: 800000 Q1: 200000 Q2: 200000 Q3: 200000 Q4: 200000 Justification: In this project we propose to check several combinations of alkane groups and silyl groups and also transesterification products of the additives with the alkyl-carbonates solvent molecules. This account for at least 12 different additive molecules. We estimate at least four reaction steps for each possible pathway. Considering two different pathways on two different surfaces, we have to compute 192 adsorption energies. Since each surface slab have about 250 atoms, we will need at least 2000 computer hours per calculation. Several initial molecule/surface configurations are needed to determine the lowest energy state. This would account for 600000 computer hours. We also will compute the energy barriers for the most thermodynamic favorable transformations in the surface of the cathode. We will use the Nudged Elastic Band (NEB) method to accomplish these calculations. These calculations would require approximately 200000 computer hours. A total of 800 000 computer hours would be needed to accomplish the proposed project. Storage requirements: 1 TB The requester has used undetermined amount hours of their initial startup project. In addition to approving an initial amount, please specify a Category and Subcategory for this project. For a list of the current selection of approved categories, please see: https://wiki.lcrc.anl.gov/wiki/Processes/Categories Once the Allocation committee has approved the project, please go to the Project Management page to create it: https://accounts.lcrc.anl.gov/projects.php Thank You, The LCRC Accounts System