A high performance polysiloxane-based single ion conducting polymeric electrolyte membrane for application in lithium ion batteries

Abstract

We report a polysiloxane based single-ion conducting polymer electrolyte (SIPE) synthesized via hydrosilylation technique. Styrenesulfonyl (phenylsulfonyl) imide groups were grafted on the highly flexible polysiloxane chains followed by lithiation. The highly delocalized anionic charges in the grafted moiety give rise to weak association with lithium ions in the polymer matrix, resulting in lithium ion transference number close to unity (0.89) and remarkably high ionic conductivity (7.2 ×10 -4 Scm -1 ) at room temperature. The high flexibility arising from polysiloxane enables the glass transition temperature (T g ) to be below room temperature. The electrolyte membrane displays high thermal stability and a strong mechanical strength. A coin cell assembled with the membrane comprised of the electrolyte and poly(vinylidene-fluoride-cohexafluoropropene) (PVDF-HFP) performs remarkably well over a wide range of temperature with high charge-discharge rates.12 rule in a three step cyclic process.[36] Following the same mechanism, here, the vinylic part of SPSIK was attached to the polysiloxane chains upon addition of a Si-H bond.The grafting of SPSIK on PMHS chains followed by exchange of K + ions by Li + ions was clearly proven to be successful by FTIR and NMR spectra. As can be seen in the FTIR spectra of PMHS and SG (Fig. 1), the peak at 2167 cm -1 in PMHS, corresponding to Si-H bond, is disappeared in SG, which confirms the grafting of SPSIK. In addition, the peak at 1627 cm -1 in SPSIK, corresponding to the vinylic group, is also disappeared in SG, confirming the grafting, which consumes the vinylic group. Furthermore, the signature signal of Si-H, appears at 4.68 ppm ( 1 H NMR) in PMHS, and the three peaks in the range of 6.78 to 5.31 ppm ( 1 H NMR) in SPSIK corresponding to 3 vinylic protons, are disappeared in SG, validating the grafting of SP on the PMHS chains. [43,46]. Finally, the overall synthesis of SG electrolyte was confirmed by the coherence between the expected and the found values for all the elements, except for Si, in the elemental analysis. The deviation observed for Si is mainly attributed to the incomplete digestion of Si during the analysis, which was also noticed during the elemental analysis of commercial products of Si such as PMHS and poly(methylphenylsiloxane)(PMPS) ( Table S1 in Supporting Information). The GPC analysis of SG in the tetrahydrofuran (THF) mobile phase depicts the number average molecular weight (Mn) of 84,238, weight average molecular weight (Mw) of 150,230, and poly dispersity index (PDI) of 1.78 based on the polystyrene standard.

Nanofiber Single‐Ion Conducting Electrolytes: An Approach for High‐Performance Lithium Batteries at Ambient Temperature

“…As clearly seen, the nanofabric swells and becomes translucent after soaking, inferring its good interaction between the solvent system as well as the fast kinetics of gelling, which is essential for smooth Li‐ion passivation i. e., high ionic conductivity . Additionally, the solvent uptake capacity was measured to reach 700 % in only 10 s (Figure c) and remained constant thereafter without showing any syneresis effect . The morphology of the fabric was observed by scanning electron microscopy (SEM, Figure d).…”

“…These check points limit the choice of materials and compel us to look for technological advancements for enhancing the performance of existing materials. For SICEs, which mainly include polymeric bulk materials, the real problem is their ionic conductivity which mostly remains ≤10 −4 S cm −1 at room temperature, irrespective of the chemical structure of the material , , . Interestingly, the same material's performance is enhanced when some morphological changes like porosity is introduced .…”

Gel Polymer Electrolytes for Electrochemical Energy Storage

“…The low crystallinity of the composite membrane coupled with low T g ensured its high flexibility and decent performance at room temperature. For example, the composite membrane exhibited a high ionic conductivity of 7.2 × 10 −4 S cm −1 , a LTN of 0.89, good thermal stability up to 410 °C, and good electrochemical stability up to 4.1 V. [72] Several another effective strategies have also been employed to improve the performances of single lithium-ion conducting GPEs near the ambient temperature. [73,74] It was widely accepted that the presence of intrinsic porous structure in polymer backbones and/or polymer matrixes could not only facilitate Li + ion transport in the polymers but also store a sufficient amount of organic solvents to provide the medium for www.advenergymat.de ionic conduction.…”

Expanding the chemistry of single‐ion conducting poly(ionic liquid)s with polyhedral boron anions

“…Subsequent studies were further focused on charge delocalization by bonding of electron‐withdrawing groups to sulfonate fragment (Scheme , 4 , 5 , 6 ). Afterwards came the era of SICs incorporating anions structurally similar to the well‐known bis(trifluoromethylsulfonyl)imide (TFSI) ion (Scheme , 7 , 8 , 9 , 10 , 12 ). This was later extended by the development of PILs bearing the so‐called ‘super‐TFSI’ anion (Scheme , 11 ).…”