Ionic Conduction Properties of PVDF−HFP Type Gel Polymer Electrolytes with Lithium Imide Salts

Abstract

Conduction properties of gel polymer electrolytes composed of lithium imide salts, LiN(CF3SO2)2, LiN(C2F5SO2)2, and PVDF−HFP copolymer were investigated using the pulsed-field gradient NMR and complex impedance techniques. The diffusion coefficients of the gel decreased with an increase in the polymer fraction in the gel. Carrier concentration exhibited 3 orders of magnitude variation in the fraction change in polymer from 80% to 20%. These results suggest that the polymer interacts with the electrolyte to affect the carrier concentration and mobility of the gel electrolytes. The interactive effect of polymer would be detected in the measurements of spin−lattice relaxation time (T 1). The deviation of the symmetric curve of the temperature dependence of T 1 could be divided into two components, one was consistent with the component of solution and independent of the polymer fraction and the other depended on the polymer fraction in the gel.

PMMA-based polymer gel electrolytes containing NH4PF6: Role of molecular weight of polymer

“…The relation between viscosity and mobility as given in the introduction part generally hold good for liquid electrolytes as well as for gel electrolytes at low concentrations of polymer but may not hold good at higher concentrations of polymer, where the difference between microand macro-viscosity becomes large. Similar results has also been observed for some proton conducting polymer gel electrolytes containing different weak carboxylic acids [14,[18][19][20] as well as for some lithium ion conducting polymer gel electrolytes [21][22][23]. The increase in conductivity with polymer addition is generally ascribed to be due to an increase in free ion concentration, although the exact mechanism is not yet clearly understood.…”

Interactive Effect of the Polymer on Carrier Migration Nature in the Chemically Cross-Linked Polymer Gel Electrolyte Composed of Poly(ethylene glycol) Dimethacrylate

“…We found that the interaction between the salt (and/or ion) and the polymer in the gel dominates the mobility and concentration of the carrier in the PVDF type gel. [2][3][4][5][6] Control of the interactive effect is indispensable for designing gel electrolyte material, which provides high conductivity and safety performance.…”

Lithium Coordination in Cyclic-Carbonate-Based Gel Polymer Electrolyte

“…19,31 Table 1 shows the diffusion coefficients for both ions and the solvent molecules in the pure liquid electrolyte and in the gel polymer electrolyte. For the determination of each diffusion coefficient, two samples were prepared and measured at diffusion times Δ 40 ms and at Δ 100 ms.…”