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: Linyun Liang Applicant's institution: ANL Applicant's division: MCS Project Name: Li-air_phase Project title: Atomistically Informed Mesoscale Modeling for Advanced Electrical Energy Storage Systems Associated funding: LDRD Other Systems: Science: We propose to develop a multi-scale simulation approach that can be used to understand and optimize the design of cathode materials that used in Li-air batteries for future applications. The integrated approach provides a connection from the cathode microstructure-level to the electrochemical performance cell-level. This integrated approach could potentially quantify the time-dependent evolution of complex three-dimensional cathode microstructure during the electrochemical processes in an operating Li-air battery, and in turn to feedback to battery performance by offering the opportunity to improve the fundamental understanding of the electrode microstructures at the mesoscale level through the phase-field simulation. Project description: Besides the proper utilization of electrolytes, the design and controlled growth of the cathode structure and morphology evolution represent a major technology challenge in the development of Li-air batteries, which dictates the most part of the cell energy density and efficiency, and contributes to most of its voltage overpotentials. In a porous air cathode, Li ions and dissolved oxygen move through the electrolyte and react with transferred electrons at the cathode surface to form the Li2O2. In this project, we will develop a multi-scale model to study the nucleation and growth of discharge product (Li2O2, LiO2, etc.) in a three-dimensional porous carbon cathode in Li-air batteries that based on our previous studies [1, 2]. These will integrating a phase-field model and an electrochemical model, which span length scales from the mesoscale to the macroscale with the inputs of experimental parameters and atomistic modeling based on Density Functional Theory (DFT). The three-dimensional porous cathode structure is first generated by using the phase field approach. The porosity, pore size and its distribution, tortuosity, and surface area are the very important structural properties of cathode that can be measured by the experiment through the collaboration with battery team at Argonne. Then during the discharge process, the discharge products that nucleated on the carbon surface and their growth evolution, which it will eventually decrease the porosity and block the mass transport of solvated oxygen and electrolytes. Similarly these reaction parameters can also be obtained through the experiments. At the cell scale, with the diffusion of reactant species such as the oxygen, Li+ ions and electrolyte inside the pores, and also the flow of electrons transport in the electrode, these couple electrochemical reactions will be related to the cathode microstructure evolution and the cell’s performance in phase-field model. For some of the fun damental reaction, e.g. initial nucleation of reactant species (Li+, O2-, electrolyte molecules, and LixOy species or aggregates) on carbon surfaces, the reaction and interfacial energies will be estimated based on DFT calculations (using VASP and Gauusian09 code). For this part of calculations, we will need 100,000 core-hour in order to complete our needed parameters for the phase-field model. In our phase field model, we have at least eight highly non-linear, coupled partial differential equations which must be solved numerically. In this work, the three-dimension and large size of cathode size will significantly increase the cost of the simulation time. To solve this problem, we will use our in-house developed FFTW code to solve the problem. We will need 200,000 core-hour to debug and test the algorithm and code. Thus by make use of Fusion and Blues computing resources will greatly accelerated the code development for our future exploration of 3D systems with complicated morphology. To include the other fundamental atomistic features at small length scale investigations, the input parameters such as the surface energy, reaction rate constant, diffusivities, and solubility, etc. will then be obtained either through the literature search and experimental supports through Argonne co-workers. In general, the required CPU time for carbon structural optimizations will be (8 cores/node * 8 nodes * 20 hours of run time * 100 different runs) 128,000 core-hours and for diffusion calculations is (8 cores/node * 8 nodes * 20 hours of run time * 100 different runs)=128,000 core-hours. The total time requested including some test study on large system is about 300,000 core hours. In conclusion, the total core-hour requested for this project throughout the FY2016 will be 600,000 core-hour. Publication: 1) M.J. Welland, K. C. Lau, P.C. Redfern, L. Liang, D. Zhai, D. Wolf, L.A. Curtiss, An atomistically informed mesoscale model for growth and coarsening during discharge in lithium-oxygen batteries, under review in J. Chem. Phys. 2) Linyun Liang, K. C. Lau, M. J. Welland, M. Stan, M. Anitescu, D. Wolf, and L. A. Curtiss, Mesoscale Model for the LiO2-Li2O2 Transformation in a Lithium-Oxygen Battery, in preparation Industry partnership: Project URL: Requested allocation: 600000 Q1: 0 Q2: 0 Q3: 0 Q4: 600000 Justification: A 10*10*10 nm3 system needs 8 node x 8 core x 1 hour for a single calculation. If we go to 50 * 20 * 20 nm3 system needs 8 node x 8 core x 20 hours for a single calculation. We will need at least 300 different runs. Thus, the total core-hours requested will be 600,000 core-hours. Storage requirements: 1TB 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