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S.K. Fullerton Shirey and J.K. Maranas

Molecular mobility and ion transport in solid polymer electrolytes for lithium batteries. DMR-0454672 DMR-0706402. S.K. Fullerton Shirey and J.K. Maranas. The Pennsylania State University.

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S.K. Fullerton Shirey and J.K. Maranas

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  1. Molecular mobility and ion transport in solid polymer electrolytes for lithium batteries DMR-0454672 DMR-0706402 S.K. Fullerton Shirey and J.K. Maranas The Pennsylania State University Results: QENS detects the mobility of hydrogen atoms on the PEO backbone, and reveals two dynamic processes: 1st process: motion of PEO backbone 2nd process: restricted rotation on a circle The liquid-phase electrolyte used in rechargeable batteries precludes a light and flexible design, and creates end-of-life disposal issues. Replacing the liquid electrolyte with a solid polymer electrolyte [SPE] would eliminate these drawbacks; however, lithium-ion [Li+] mobility through the SPE (quantified as the ionic conductivity) is insufficient to power a portable device. Ion mobility increases with increasing polymer mobility, but conductivity values in a fully-crystalline sample (low polymer mobility) are higher than in the amorphous equivalent, owing to the formation of cylindrical polymer channels that direct ion transport [1]. We use quasi-elastic neutron scattering [QENS] to learn more about the molecular-level mobility of the channels.[2] QENS results for PEO/LiClO4 Increasing Li+ Concentration (decreasing polymer mobility) A second process has been observed in other SPEs where the channels form. The radius of the rotating structure corresponds to the radius of the PEO/Li+ channel measured by diffraction.[3] 3Å Conclusion: We attribute the second process to the restricted rotation of the PEO/Li+ channels. This motion could reflect the local reorganization of PEO to accommodate Li+ transport. Understanding this mechanism is important for designing a SPE with adequate conductivity to operate at room temperature. Data is fit to the Kolraush-Williams-Watts (KWW) expression 2 PEO chains Li+ ion Polymer: PEO(Polyethylene oxide) Side view Susan Fullerton Shirey 2009 Frank J. Padden Jr. Award Recipient Janna Maranas Associate Professor Chemical Engineering [1] Z. Gadjourova et al., Nature. 412(6846), 520 (2001). [2] S.K. Fullerton-Shirey, J.K. Maranas, Macromolecules, 42(6), 2142 (2009). [3] G. Mao et al, Europhysics Letters. 54(3), 347 (2001).

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