IR spectroscopy and quantum mechanical calculations of lithium ion transport conditions in a single ion conducting polymer electrolyte

Lithium single ion conducting polymers with good conductive properties has the potential of boosting the performance of lithium batteries considerably. Recently, lithium single ion conducting polymer electrolytes were obtained by solvating 'polymeric salts' into polyether matrices. Of the polymeric salts developed, the highest ion conductivity was obtained using poly(5-oxo-3-oxy-4-trifluoromethyl-1,2,4-pentafluoro-pentylene sulphonyl imide lithium) (LiPPI). In the present study ab initio calculations have been used to determine limitations for ion transport in a model system similar to the LiPPI. The lithium ion coordination and the flexibility of the polymer backbone have been studied using monomers and dimers of our model system. Comparisons with calculated IR spectra from our model system and experimental IR spectra of LiPPI in solution show that our model is a good description of the LiPPI system. The present results are used to propose structural changes that may increase the single ion conductivity. (C) 2004 Elsevier Ltd. All rights reserved.