Design of a Boron-Containing PTHF-Based Solid Polymer Electrolyte for Sodium-Ion Conduction with High Na⁺ Mobility and Salt Dissociation

Abstract

Solid polymer electrolytes based on semi-interpenetrating polymer networks (semi-IPNs) were developed for sodium-ion conduction using a boron-centered moiety with polytetrahydrofuran (PTHF) chains. The resulting solid polymer electrolytes (SPEs) combined the anion-trapping properties of the boron with the weakly coordinating PTHF to achieve enhanced salt dissociation and transference number. The structure of the polymer was confirmed by 1H NMR, 13C NMR, and 11B NMR, and the cross-linking reaction with hexamethylene diisocyanate (HMDI) was confirmed by Fourier transform infrared (FTIR) spectroscopy. The mechanical and thermal stabilities of the samples were evaluated, and FTIR spectroscopic analysis showed the efficiency of the boron centers in complexing with ClO4 –. Dielectric studies also indicated the predominance of free Na+ in samples. The highest room-temperature ionic conductivity was delivered by boron-containing electrolytes with O/Na: 5, 7.54 × 10–5 S cm–1, and O/Na: 10, 1.13 × 10–5 S cm–1. Linear sweep voltammetry (LSV) revealed suitable electrochemical stability against Na metal, and the measured transference number was 0.88, confirming that electrolytes benefit from the looser coordination of Na+ ions with PTHF chains combined with the anion-trapping performance of boron moieties, indicating a potential direction in polymer electrolyte design.

The Effect of Boron Nitride Flakes on Sodium Ion Transport in PEO Electrolytes

“…20 In both cases, an increased cation transference number was observed due to the ability of boron to trap anions. Genier and co-workers 21 reported similar findings as well as higher σ due to boron. The Liu group 22,23 has also developed and investigated Na-ion batteries comprising boron-containing GPEs.…”

NMR studies of polymeric sodium ion conductors—a brief review

“…Other EIS experiments indicate a thick SEI, confirming the cause of cycle stability, though at the sacrifice of higher charge transfer resistance, reducing specific capacity and polarization. Genier et al, developed a solid polymer electrolyte based on semi-interpenetrating polymer networks (semi-IPNs) (Genier et al, 2022). Boron-centered polytetrahydrofuran (B-PTHF) and hexamethylene diisocyanate (HMDI) cross-linker were dissolved in N-methyl-2-pyrrolidone (NMP) (solution I).…”

“…CDCl 3 was used as solvent. Reproduced with permission from Ref (Genier et al, 2022). ACS Applied Polymer Materials, vol.…”

Hexagonal Boron Nitride Modulates Crystallinity and Charge Mobility in Poly(ethylene oxide)–NaNO3 Electrolytes

“…Similar findings along with increased ionic conductivity have been reported by Genier and co-workers. 32 Last, the physical incorporation of boron nitride nanosheets to GPEs by Liu and co-workers resulted in a marginal increase in total ionic conductivity. 33,34 While salts with low lattice energies and anions with high delocalization of charge are preferred for ionic conductivity enhancement, we choose NaNO 3 as a model salt in this work owing to its low cost and ease of availability, with the focus being on the effect of filler addition on structure− property relationships in the CSPEs.…”

“…In the context of energy storage, investigations of structure–property relationships in BN-containing polymer electrolytes for Na-ion conduction are lacking. To the best of our knowledge, only a handful of recent reports have devoted attention to such polymer electrolyte systems. − Only one of these reports is based on a CSPE for Na-ion conduction, whereas the remainder of the studies is based on the incorporation of boron into the polymer chain rather than adding a BN-based filler to the polymer matrix. Chen et al , chemically incorporated boron into polymer chains and found a decrease in the total ionic conductivity compared to full-carbon polymer matrices.…”