Salt-in-Polymer Electrolytes Based on Polysiloxanes for Lithium-Ion Cells: Ionic Transport and Electrochemical Stability

In this work, the ion transport and the electrochemical stability has been investigated for cross linked salt-in-polysiloxane membranes containing the two lithium salts with boron based anions, i.e. LiDFOB (lithium difluoro(oxalato) borate) and LiBOB (lithium bis(oxalato) borate) have been investigated. The stability was characterized by cyclic voltammetry at 70 degrees C in a three electrode cell with Li as counter and reference electrodes and a nickel or platinum working electrode. The electrochemical stability window of polysiloxane based electrolytes ranged between 0 V and 4.7 V vs. Li/Li+. The high ionic conductivity of 6.61 x 10(-2) mS/cm at 30 degrees C has been examined with impedance spectroscopy on blocking electrodes. The investigated polymer electrolytes showed an outstanding thermal resistance as confirmed by thermal analysis with DSC. Furthermore, analysis of the lithium transference number has been carried out using the potentiostatic polarization method introduced by BRUCE and VINCENT.