Enhanced ion conductivity of poly(ethylene oxide)‐based single ion conductors with lithium 1,2,3‐triazolate end groups

Abstract

Poly(ethylene oxide) (PEO)-based single ion conductors (SICs) are of great interest for applications in modern lithium ion batteries. They have several advantages over other common electrolytes such as high cation transference numbers, low toxicity, and nonflammability, but their major disadvantage is the low ion conductivity. Here, linear PEO-based SICs with lithium 1,2,3-triazolate (TrLi) end groups are synthesized and studied in terms of crystallinity by differential scanning calorimetry, and with respect to ion conductivity by impedance spectroscopy. Introduction of TrLi end groups to PEO chains reduces its crystallinity and melting temperature as well as an enhancement of the ion conductivity up to 8.0Á10 −6 S cm −1 at 70 C is observed. The increased ion conductivity is a direct result of the Tr rings, which can actively contribute to the conduction mechanism. In comparison with conductivities of other PEO-based SICs reached so far (σ 0 ≤ 10 −6 S cm −1 ), the results of this study show that the introduction of TrLi end groups is a new approach to enhance the Li + -ion conductivity of PEO-based SICs that have also a good electrochemical stability versus lithium electrodes as revealed by linear sweep voltammetry.

The Effects of Magnetic Field Alignment on Lithium Ion Transport in a Polymer Electrolyte Membrane with Lamellar Morphology

“…Instead, the conductivity data are dominated by the PEO melting transition and all three plots show a clear break in the scaling of conductivity near the melting temperature, T M , of PEO, from which we can infer a significant decrease in the activation energy for ionic transport in the PEO melt compared to the PEO crystal. Similar strong dependence of activation energy on electrolyte backbone crystallinity has been reported [39]. In the case of 50:1 EO:Li + there is approximately a 7-fold reduction in the activation energy from ~39 k B T 298 (~1 eV) to 5.5 k B T 298 (~0.14 eV).…”

Development of the PEO Based Solid Polymer Electrolytes for All-Solid State Lithium Ion Batteries

“…Due to the immobilizing of the anion, a single ion conductor presents a high lithium transport number. Besides that, the single ion conductor can also inhibit the reaction between the anion and electrode, which facilitates a reduction in the passivation layer on the electrode surface, thus enlarging the operating voltage window of the battery [27,64,65]. To simultaneously enhance ionic conductivity, lithium transport number, and mechanical properties, Bouchet et al designed a new single-ion polymer electrolyte based on self-assembled polyanionic BAB triblockcopolymers P(STFSILi)–PEO–P(STFSILi), as seen in Figure 7, where the B block was based on poly(styrene trifluoromethanesulphonylimide of lithium) P(STFSILi) and the central A block was based on a linear poly(ethylene oxide) (PEO) [66].…”

Comparison of Li+‐ion conductivity in linear and crosslinked poly(ethylene oxide)

“…During the reaction, 1,4‐disubstituted 1,2,3‐triazole rings are formed which connect the three‐arm star PEO and linear chains resulting in a PEO network. It should be noted that the presence of these triazole rings in the network might have a great influence on the ion conductivity since they can actively contribute to the transport of Li + ‐ions and increase the dissociation of the dissolved lithium salts . Four different lithium salts, namely, LiTFSI, lithium bis(oxalato)borate (LiBOB), lithium perchlorate (LiClO 4 ), and lithium hexafluorophosphate (LiPF 6 ) have been employed for the electrolyte preparation.…”