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: Paul Redfern Applicant's institution: ANL Applicant's division: CSE Project Name: Redoxshuttles Project title: Redox Shuttles and Additives for Lithium-Ion Batteries Associated funding: EER-DOE Other Systems: Small Group Cluster Science: There are several types of electrolytes that are used to improve the performance of the batteries. Some electrolyte additives are used to improve lithium-ion battery performance by facilitating solid-electrolyte (SEI) formation, reducing irreversible capacity and gas formation, improving thermal stability, protecting cathode materials, improving electrolyte properties, decreasing flammability and providing overcharge protection. It is also desirable to develop additives that can stabilize electrolytes near 5 V in order to deliver energy at higher density and potential. Numerous additives have been developed that improve some aspect of battery performance, but many introduce negative side effects. A second type is used to prevent dangerous overcharge of lithium-ion batteries occurs when charge from current forced through a cell exceeds its charge storing capability, leading to chemical and electrochemical reactions, rapid temperature rise, self accelerating reactions and explosion. Redox shuttle molecules are additives that are reversibly oxidized and reduced at potentials slightly higher than the end of charge cathode potential, locking the cathode potential at the oxidation potential of the redox shuttle and thereby preventing overcharging. The shuttling mechanism can be regarded as an internal short that can be repeated continuously due to reversible oxidation and reduction of the shuttle molecule. Redox shuttles with excellent performance and compatibility are critically important to the development of lithium-ion battery technology. Development of new redox shuttles is difficult and has been largely based on trial and error due to the multidisciplinary knowledge r equired. Ideal redox shuttles should be electrochemically reversible, have a redox potential slightly higher than the cathode end of charge potential, be electrochemically stable, have good solubility and high diffusion coefficients, and be compatible with the cell, i.e., they should not adversely affect normal cell performance. The shuttle should not react with electrolytes, the solid-electrolyte interface, separators, current collectors, binders, etc. Interface resistance and thermal properties should also be considered. Project description: Benchmark calculations using high level ab initio approaches such as G4 will be performed. Oxidation and reduction potentials are calculated by optimizing the geometries of the neutral and ionic species with B3LYP/6-31G*, followed by frequency calculations to get the gas phase free energies. Then solvation effects are taken into account using a single point B3LYP/6-31+G* pcm calculation with the default (water) solvent and a dielectric constant of 55.725 representing the electrolyte (25% EC, 25% ethyl methyl carbonate, 50% PC). Finally basis set effects are taken into account with a B3LYP/6-311+g(3df,2p) single point calculation. From these results the total free energy of each species is calculated as electronic energy plus gas phase free energy plus solvation free energy. The free energies of the neutral and ionic species are then subtracted to get an absolute free energy difference. During this process the electron affinity (reduction potential) or ionization potential (oxidation potential) is calculated. We intend to evaluate at least 200 redox shuttles including tert-butyl substituted benzenes, biphenyls, terphenyls and quaterphenyls. High redox shuttle oxidation potentials are required for high voltage applications. We will also examine at least 200 SEI additives including carbonates, anhydrides, imides, cyclic phosphates, and borates, as well as many others. Reduction potentials of SEI additives must be higher than the electrolytes. Using theoretical results, databases will be developed to screen for new additives using quantitative structure-property relationships and physical organic chemistry principles. New redox shuttles and SEI additives will be developed for high voltage applications. We intend to use Gaussian 09 for quantum chemical calculations. In Gaussian 09 the DFT calculations scale well up to 64 processors, however the high-level ab initio methods scale only up to 16 processors. Project URL: Requested allocation: 400000 Q1: 100000 Q2: 100000 Q3: 100000 Q4: 100000 Justification: We intend to use Gaussian 09 for quantum chemical calculations. In Gaussian 09 the DFT calculations scale well up to 64 processors, however the high-level ab initio methods scale only up to 16 processors. Therefore these calculations do require a longer execution time. 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