DEVEGA

The development of new technologies for electrochemical energy storage is one of the main challenges of the next decades. Many hopes now rely on lithium-ion batteries that have invaded the market of laptops and which appear to be the best choice with the short time for electric vehicles, and perhaps for network applications (electricity storage from wind turbines or solar cells for example). Many works concern the search of cathodes with high-energy density. The lithium-rich layered oxides generate a strong interest due to their high capacities in spite of their cycling performances that are still limited for being presently used in high energy density lithium-ion batteries. Our recent studies have shown that this extra-capacity comes from the unusual couple O2-/O22- involved in the redox process, which gives rise to the development of compatible electrolytes. This project aims at developing a rational strategy, which is at odds with the traditional approaches "Testing and Checking" to identify new electrolytes stable to high voltage. Such an approach relies on (i) the design of new electrolytes by using modern calculation tools used in screening techniques based on DFT and QSPR calculations (Density Functional Theory and Quantitative Structure-Property Relationship, respectively) as well as the knowledge of the mechanisms responsible for the electrolyte oxidation on lithium-rich layered oxides, (ii) the synthesis of the best structures identified by in-silico calculations, and (iii) the investigation of the physicochemical and electrochemical properties of electrolytes formulated in the present project. The goal of this project is thus to find an electrolyte, which can be used in high-voltage batteries for high energy density applications such as electric vehicles. This collaborative challenging project involving research groups from Paris, Rouen and Strasbourg is based on a multidisciplinary approach and combines highly and specific complementary skills of different research groups in organic chemistry, electrochemistry, solution chemistry, thermodynamics and theoretical chemistry. This project will focus on the design of dipolar organic solvent such as lipophilic sufides, sulfones, alkyl carbonates and ethers bearing more or less steric hindrance and containing electronegative atoms like fluoride since fluoride atoms may be responsible for an improvement of the anodic resistance by modifying the energy of HOMO orbitals whereas high steric hindrance will bring a protection of the fragile sites of the molecules. Conversely, the design of new lithium salts will not be tackled since it is commonly admitted that electrolyte decomposition pathways mostly involve the solvents and not the salts. Last but not least, this project will bring strong scientific, technologic and economic benefits in a very competitive environment as it would pave the way to the development of new batteries allowing the development of electric vehicles that can be used for long distance trips.