Effect of polymerizing on lithium-ion transport in electrolyte

The effect of polymerizing 1,3-dioxolane (DOL) on the transport properties of the lithium (Li) ions in electrolytes from liquid to gel has been studied. After polymerization, liquid DOL electrolytes (LDOLEs) can form poly(1,3-dioxolane) (PDOL)-based electrolytes (PDOLEs), a gel polymer electrolyte with DOL as self-plasticizer. The chemical environment of Li + ions is investigated with 7 Li nuclear magnetic resonance (NMR) and Raman spectrum. Compared with LDOLEs, the 7 Li NMR peaks of PDOLEs show upfield shift and increased full width at half-maximum, indicating more substantial shielding effect and larger Li + solvates. The diffusion coefficients of Li + ions ( D Li + ) are determined with pulsed field gradient NMR. The D Li + in PDOLEs decreases about two orders of magnitude than that in LDOLEs. Larger activation enthalpy is needed for PDOLEs than LDOLEs to change the coordination state of Li + ions due to the necessity of cooperative movement of several chain segments. The effect of bis(trifluoromethane)sulfonimide lithium salt concentration on the D Li + is mainly ascribed to the change of mixing entropy (Δ S ). In PDOLEs, the Δ S caused by the concentration variation has a more significant influence on the D Li + than that in LDOLEs.