Hello, A yearly allocation for the LCRC cluster has been requested with the following updated information: Submitter/PI: Paul Redfern Project Name: Redoxshuttles Division: CSE Project title: Redox Shuttles and Additives for Lithium-Ion Batteries Associated funding: EERE-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: Over the past year we have examined many redox shuttles and electrolytes for high voltage applications. Calculations were performed on several substituted quaterphenyls. Oxidation potentials were found to be sensitive to the position of substituent and the effects are approximately additive even when substituents have opposite push-pull effects. Hammett sigma parameters were also calculated. In collaboration with experimentalists we developed a new platform to build redox shuttles involving a fused cyclohexene ring on a benzene ring. Numerous high voltage electrolyte candidates were also examined including lactones, cyclic sulfates and fluorinated species. Electrolytes with high dielectric constants and electron withdrawing groups such as F or SO2 have increased oxidative stability. There are still many avenues to be explored. Quantum chemical calculations will be used to calculate additive oxidation and reduction potentials and to investigate mechanisms of solid-electrolyte interface formation and additive decomposition reactions. Effects of electron donating and withdrawing groups on additive performance will be investigated. Oxidation potentials and decomposition reactions of redox shuttles will be determined. 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 (o xidation potential) is calculated. We intend to evaluate at least 200 redox shuttles including biphenyls and terphenyls and fused hexene ring substituted benzenes. 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. Software 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. Publications 1) Asymmetric form of redox shuttle based on 1,4-di-t-butyl-2,5-dimethoxybenzene, Wei Weng, Yunting Tao, Zhengcheng Zhang, Paul C. Redfern, Larry A. Curtiss, and Khalil Amine, accepted. 2) Fluorinated electrolytes for 5 V lithium-ion battery chemistry, Zhengcheng Zhang, Libo Hu, Huiming Wu, Wei Weng, Meiten Koh, Paul C. Redfern, Larry A. Curtiss and Khalil Amine, Energy Environ. Sci., 2013, 6, 1806. 3) Smart Polymeric Cathode Material with Intrinsic Overcharge Protection Based on a 2,5-Di- tert butyl-1,4-dimethoxybenzene Core Structure, Wei Weng , Zhengcheng Zhang , * Ali Abouimrane , Paul C. Redfern , Larry A. Curtiss , and Khalil Amine, Adv. Funct. Mater. 2012, DOI: 10.1002/adfm.201200458 4) Molecular engineering towards safer lithium-ion batteries: a highly stable and compatible redox shuttle for overcharge protection, Lu Zhang , Zhengcheng Zhang , Paul C. Redfern , Larry A. Curtiss and Khalil Amine, Energy Environ. Sci., 2012, 5, 8204-8207. 5) Improved synthesis of a highly fluorinated boronic ester as dual functional additive for lithium-ion batteries, Wei Weng; Zhengcheng Zhang; Schlueter, J.A.; Redfern, P.C.; Curtiss, L.A.; Amine, K., Journal of Power Sources, 2011, 196, 2171-2178. 6) Fused ring and linking groups effect on overcharge protection for lithium-ion batteries, Wang, W (Wang, Wei)1; Zhang, ZC (Zhang, Zhengcheng)1; Redfern, PC (Redfern, Paul C.)1; Curtiss, LA (Curtiss, Larry A.)1,2,3; Amine, K (Amine, Khalil)1, JOURNAL OF POWER SOURCES, 2011, 196, 1530-1536. 7) Understanding the redox shuttle stability of 3,5-di-tert-butyl-1,2-dimethoxybenzene for overcharge protection of lithium-ion batteries, Zhengcheng Zhang; Lu Zhang; Schlueter, J.A.; Redfern, P.C.; Curtiss, L.; Amine, K., Journal of Power Sources, 2010, 195, 4957-4962. Project URL: Current FY Hours Used: undetermined amount New FY Requested allocation: 400000 Q1: 100000 Q2: 100000 Q3: 100000 Q4: 100000 Justification: Thank You, The LCRC Accounts System