Investigation of the Structure and Dynamics of Electrolytes in solvents Used for Primary and Secondary Li-Batteries

摘要

During the past three years, we have investigated the structure and dynamics of lithium electrolytes in solvents of low permittivity as ethers and dimethyl carbonate. These systems are highly relevant for the construction of batteries using lithium anodes. It appeared necessary to offer the electrolyte species present in the electrolyte solutions and the lifetime and structure of these species. This information is essential for an optimum choice of the electrolyte solution to be used for battery planning and construction. To the above end we have used Raman spectra (occasionally), electrical conductance, microwave dielectric relaxation and radio frequency ultrasonic relaxation. Many systems show a significant amount of quadrupoles or dimers present in the solution. Theoretical expression for the formation constant K sub q of dimers and enthalpy, entropy, isothermal and adiabatic volume changes have been calculated from statistical thermodynamic augments. In particular, a Bjerrum-type theory for associated of electrolytes (AB) to dimers (AB)2 has been developed. Additional keywords: Lithium batteries; Army Research Laboratories; Lithium salts.