Poly(ethylene oxide) (PEO) based electrolytes are widely used in lithium-ion batteries for their good conductivity and stability among a variety of polymer electrolytes. The conductivity of lithium with PEO (typically below 10−4 S cm−1 at 298 K)3 is yet to be optimized. Synthetic modifications by incorporating secondary sites into the PEO backbones have shown promising results in enhancing the conductivity and lowering the glass-transition temperature. However, to date, there still lacks rigorously tested structure-property relationship that guides future designs. Therefore, in this work, we systematically vary the structure of oligomeric and polymeric ethylene oxide-based electrolytes. Our central hypothesis is that synthetically introducing different secondary sites into PEO will result in variable affinity between lithium and the electrolyte molecules. Strong lithium affinity helps dissociate non-conducting ion pairs but also induces inter-chain cross-linking. We will investigate the lithium conductivity, glass-transition temperature, and lithium association of these synthesized compounds to test our hypothesis and identify an ideal balance between salt dissociation and cross-linking.

Structure-property relationship of lithium electrolytes

256th National Meeting (2018)

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