New Model Solid Polymer Electrolyte Discovery

The Simulated Annealing Method of Ab Initio Structure Determination from Powder Diffraction Data. We developed a method capable of solving ab initio complex crystal structures which contain individual atoms and/or highly flexible molecular fragments. The method employs a global optimisation technique and a versatile description of flexible molecular moieties in terms of stereochemical descriptors (bond lengths, bond angles and torsion angles) The power of the method was first demonstrated by solving the previously unknown crystal structure of (CH2CH2O)3:LiN(SO2CF3)2 (Andreev YG, Lightfoot P, Bruce PG. "Structure of the polymer electrolyte poly(ethylene oxide)3: LiN(SO2CF3)2 determined by powder diffraction using a powerful Monte Carlo approach" Chem. Comm.(18): 2169-2170 SEP 21 1996):

Overlap of powder diffraction peaks coupled with the complexity of the structures sometimes precludes unambiguous structure determination from powder diffraction data alone, even by such a powerful method as simulated annealing. However, some of the polymer electrolyte structures can be successfully solved using our approach of combining the results of structure determination obtained by single crystal diffraction (from a complex prepared with a low-molecular-weight polymer), with the structure refinement by the Rietveld method of the powder diffraction data (from a complex prepared with a high-molecular-weight polymer). For the first time this method was successfully applied to (CH2CH2O)8:NaBPh4 (Staunton E, Christie AM, Andreev YG, Slawin AMZ, Bruce PG "The structure of poly(ethylene oxide)8 : NaBPh4 from a single crystal oligomer and polycrystalline polymer" Chem. Comm.(2): 148-149 2004):