Ester Compounds as Novel and Environmental Friendly Solvents for Electrolytes in Li-Ion Batteries

摘要

In the last years, the market for portable energy sources expanded strongly. In this context, the need of organic solvents and other materials for the production of the batteries has increased, too. This development will continue in the next years. The solvents that are used for the electrolytes in the common batteries are mostly organic compounds, which are very often volatile, flammable and dangerous for the environment. In case of an accident, the battery may leak and it might result in a fire of the organic solvent. Due to this, one aim of research is to replace these dangerous solvents by less- or non-volatile compounds, which are also nonflammable and non-toxic [1]. In this work, we present the use of some ester compounds as solvent for the electrolyte, which are non-flammable and non-toxic. These ester compounds are for example triacetin, which is also used as a food additive, or propyl acetate, which is used as a component in cosmetics. All of the investigated ester compounds are also easily biodegradable. The ester compounds were used as solvents for common lithium salts like lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) or lithium bis(oxalato)borate (LiBOB), so that the influence of the new solvents to the resulting electrolytes can be compared to well-studied standard systems. The new electrolytes were characterized regarding the conductivity (electrochemical impedance spectroscopy / EIS) and electrochemical stability (cyclic voltammetry / CV). Thermodynamical properties were determined by using differential scanning calorimetry (DSC).