Hello, A yearly allocation for the LCRC cluster has been requested with the following updated information: Submitter/PI: Kah Chun Lau Project Name: Li_air_battery Division: MSD/CNM Project title: Computational studies of Li-Air battery components Associated funding: LDRD Other Systems: CNM, EMSL-PNNL Science: Unlocking the true energy capabilities of the lithium metal (negative) electrode in a lithium battery has been mainly limited by the low capacity in intercalation and conversion reaction at the positive electrodes. However, it can be overcome by removing these electrodes and allowing lithium to react directly with oxygen in the amosphere, forming the lithium-air battery as being a hybrid battery-fuel cell system. Compared to other metal-air batteries, Zn-air and Al-air cells have aqueous electrolytes and operate at a relatively low voltage of ~1.4 V and ~1.2 V, respectively, whereas for the non-aqueous Li-air cells, it provides ~3 V and therefore yields a significantly higher specific energy. During the electrochemically reduction of oxygen, the small yet highly reactive Li cations tend to form ionic bonds in terms of lithium (per)oxides (i.e. Li2O2 and Li2O) leading to their precipitation on the electrode surfaces. These surface coverage species by the O2 reduction products passivate the electrode, shut down the reduction, and render the reaction irreversible. The formation of Li2O and Li2O2 are both thermodynamically possible at nearly identical potential (~ 3V), however, the physical and chemical properties of these compounds remain elusive, a systematic theoretical study of these system are therefore critically important. Lithium-air cells can be considered the 'holy grail' of lithium batteries because they offer, in principle, a significantly superior theoretical energy density to conventional lithium-ion systems. While the inherent energy potential of lithium metal approaches that of gasoline, today's battery manufacturers have not yet been able to unlock this potential because of : (1) the non-aqueous electrolytes are unstable at high potentials and are easily oxidized by the oxygen released during charge, thereby seriously limiting cycle life; (2) during discharge, the solid and insoluble Li2O2 and/or Li2O products are deposite d on the surface or within the pores of the carbon cathode, thereby clogging the pores and restricting oxygen flow; (3) poisoning of the lithium electrode due to oxygen crossover destroys the integrity and functioning of the cell; and (4) commonly used cathode catalysts, such as metals, metal complexes, and metal oxides, do not access the full capacity of the oxygen electrode or enable sufficiently high rates. Thus in the computational studies, these problems will be addressed and explored based on state-of-the-art atomistic modeling techniques. This is a project in its second year that was awarded a Grand Challenge LDRD. Project description: This work will be done in close collaboration with the Energy Storage Program at Argonne and will focus on the development of (1) new electrolytes, (2) cathode catalysts, and (3) electrode/electrolyte designed interfaces. In the work on electrolytes the objective of this project is to investigate chemical and dynamical properties of the silicon based electrolytes, a potential electrolyte that is stable at high potentials required in the Li-Air batteries. We will use computational chemistry, ab initio and classical molecular dynamics methods. We intend to study thermochemistry, oxidation potentials, and kinetics of possible decomposition of silicon based electrolytes using density functional methods and high-level ab initio methods. We will study the effect of various substituents, such as electron withdrawing groups, electron donating groups on stability and oxidation potential behavior of siloxanes and disiloxanes. To explore the thermal stability and i onic diffusion of the mobile charges in silicon based electrolytes, ab initio and classical molecular dynamics will be used. By incorporating the strengths of these different simulation techniques, ultimately it will enable us to design better and more appropriate electrolytes for the rechargeable batteries. In the work on the cathode catalysts, computational modeling will play an integral part in collaboration with experimentalist as a team. The work will focus on (1) understanding catalytic processes and (2) design of improved catalytic components for the cathode to improve the oxygen reduction reaction activity (ORR). Density functional calculations will be carried out to determine the reaction mechanism involved in breaking and making the Li-O bonds in the cathode compartment and surface chemistry of Li-air cells. This will include calculations of discharge potential, adsorption energies, intermediates, transition states of various reaction pathways to determine the rat e-determining steps of ORR. In addition, screening of potential catalyst candidates for optimal Li-O bond breaking and making properties will be undertaken. This will involve the derivation of descriptors that correlate with properties such as key reaction barriers, which need to be optimized for the catalysts to perform optimally. In the work of electrode/electrolyte designed interfaces, the both ab initio and classical molecular dynamics methods will be employed in collaboration with experimentalist at Argonne. We will utilize results from characterization studies such as those to be carried out at the APS to gather structural information. The work will focus on utilizing the computational model to design a well-tailored electrode/electrolyte interface of Li-air battery based on our works in electrolyte and electrode catalytic studies to fine-tune the charge transfer, transport and diffusion in the battery. In this work, we will utilize the software (GPAW, DACAPO) being de veloped as a part of a new ANL computational materials design program for catalysts and energy research. This software is being developed in collaboration with Mathematics and Computer Sciences Division. The requested time is 900,000 core-hours. Project URL: Current FY Hours Used: undetermined amount New FY Requested allocation: 900000 Justification: The electrolyte work will involve largely Gaussian, NWCHEM and VASP calculations. In Gaussian 03, the DFT calculations scales well up to 8 processors, however the high-level ab-initio methods scale only up to 2 processors. Based on our experience with these types of calculations, about 100,000 hours will be required. The work on the catalyst development will be largely done with VASP, DACAPO, GPAW codes. Six nodes (or 48 Fusion cores) is the optimal number of nodes for these types of jobs. Our experience indicates that for catalysts design using these codes will likely require about 400,000 hours. The most computationally intensive calculations are the nudged elastic band calculations to map out a complete potential energy surface. Each of these will require about 15,000 core-hours. Besides DFT and quantum chemistry based methods, the bigger system of bulk electrolytes and large nanoparticles of Li2O/Li2O2 on electrode/electrolyte interfaces will be computed u sing DL_POLY and LAMMPS codes. These classical molecular dynamics codes are well-parallelized and usually can deals up to ~ 100 thousands of atoms for various systems. Based on our estimation, the jobs will likely require about 400,000 hours. Thank You, The LCRC Accounts System