Electrochemistry of novel lithium salt complexes in non-aqueous poleyther and gel media

Abstract

Electrochemical studies have been performed on some novel lithium salt complexes in polyether media, propylene carbonate and poly(methyl methacrylate) gels. The electrochemical performances of these electrolytes containing added ligands were assessed with particular attention given to their applicability to modern lithium rechargeable battery systems. Conductivity data was obtained for complexes of lithium hexafluorophosphate in non¬ aqueous polyether media and propylene carbonate over a wide range of concentration (10^-3 M to 1M) and analysed using the Fuoss-Kraus, Fuoss (1978) and Casteel-Amis methods. The electrolyte parameters, namely molar conductivity at infinite dilution, dissociation constants for ion-pairs and triple-ions, and maximum specific conductivities, have been obtained. These parameters, particularly at low salt concentration, have been interpreted in terms of ion-ion interactions. Kinetics and mechanisms for the electrodeposition of lithium from non-aqueous solvents and gel media were studied using chronoamperometric, cyclic voltammetric and chronopotentiometric methods at a microelectrode. Nucleation and crystal growth models have been proposed for each electrolyte. Exchange current densities, coulombic stripping efficiencies and lithium corrosion rates were evaluated.