Nanostructured Single-Ion-Conducting Hybrid Electrolytes Based on Salty Nanoparticles and Block Copolymers

Abstract

We report on the synthesis and characterization of a series of microphase-separated, single-ion-conducting block copolymer electrolytes. Salty nanoparticles comprising silsesquioxane cores with covalently bound polystyrenesulfonyllithium (trifluoromethylsulfonyl)imide (PSLiTFSI) chains were synthesized by nitroxidemediated polymerization. Hybrid electrolytes were obtained by mixing the salty nanoparticles into a microphase-separated polystyrene-b-poly(ethylene oxide) (SEO) block copolymer. Miscibility of PSLiTFSI and poly(ethylene oxide) (PEO) results in localization of the nanoparticles in the PEO-rich microphase. The morphology of hybrid electrolytes was determined by scanning transmission electron microscopy. We explore the relationship between the morphology and ionic conductivity of the hybrid. The transference number of the electrolyte with the highest ionic conductivity was measured by dc polarization to confirm the single-ion-conducting character of the electrolyte. Discharge curves obtained from lithium metal−hybrid electrolyte− FePO 4 batteries are compared to the data obtained from the batteries with a conventional block copolymer electrolyte.

Solid-State NMR Study of New Copolymers as Solid Polymer Electrolytes

“…This partial rigidity of pendant groups possibly results from their coordination with lithium salts. Furthermore, the 13 C NMR results show that the phase segregation reported by Daigle et al [12] is not complete and that a model consisting of two perfectly separated blocks has to be refined. As the PS fraction is reduced, the efficiency of the cross-polarization decreases.…”

“…Consequently, the study of this polymer by solid-state NMR is an interesting tool for elucidating the lithium motion. The rigidity of the structure is assessed by solidstate 13 C NMR, and an improved understanding of the polymer micro-structure is obtained, as reported in the case of cross-linked polymers [21]. The purpose of this study is to develop a relationship between the lithium mobility and the electrochemical results.…”

“…Figure 1 shows the results for three different polymers with differing PEGMA to PS ratios. Cross-polarization solid-state 13 C NMR (left column) and direct pulse solid-state 13 C NMR excitation (right column) of samples 1 to 3 at 298 K. All spectra are normalized by maximum peak intensity; the change in noise level thus reflects the amount of rigid segments in the polymer.…”

“…Figure 2 shows the evolution of 13 C spectra for sample 3 with temperature. shown in Figure 1, sample 3 appears to have a stronger rigid phase component compared to samples 1 and 2.…”

“…Using elegant polymer architectures with rigid and soft blocks to create phase separation is now a trend in the development of a new SPE [12][13][14][15]. The development of SPEs involves complex architectures that influence the interaction between the soft and the hard blocks.…”