Insights into the structure and ionic transport in ‘water-in-bisalt’ electrolytes for lithium-ion batteries

We investigated the dynamics and transport of lithium-ion water-in-bisalt (WiBS) electrolytes that contain lithium bis(trifluorosulfonimide) (LiTFSI) and lithium triflate (LiOTf) at different concentrations and temperatures using classical molecular dynamics simulations....

Resorcinol-Formaldehyde (RF) as a Novel Plasticizer for Starch-Based Solid Biopolymer Electrolyte

A starch-resorcinol-formaldehyde (RF)-lithium triflate (LiTf) based biodegradable polymer electrolyte membrane was synthesized via the solution casting technique. The formation of RF crosslinks in the starch matrix was found to repress the starch’s crystallinity as indicated by the XRD data. Incorporation of the RF plasticizer improved the conductivity greatly, with the highest room-temperature conductivity recorded being 4.29 × 10−4 S cm−1 achieved by the starch:LiTf:RF (20 wt.%:20 wt.%:60 wt.%) composition. The enhancement in ionic conductivity was an implication of the increase in the polymeric amorphous region concurrent with the suppression of the starch’s crystallinity. Chemical complexation between the plasticizer, starch, and lithium salt components in the electrolyte was confirmed by FTIR spectra.

Determination of charge carrier transport properties of gellan gum–lithium triflate solid polymer electrolyte from vibrational spectroscopy

Mobility and number density of charge carriers are important parameters that influence the electrolyte conductivity. Therefore, knowing these parameters quantitatively is of great significance. In this work, solid polymer electrolytes have been prepared by solution casting technique using gellan gum complexes with lithium triflate (LiTf). The conductivity of the electrolyte increases from 3.35 × 10−8 S cm−1 (electrolyte with 10 wt% LiTf) to 5.38 × 10−4 S cm−1 (electrolyte with 40 wt% LiTf). The increase in conductivity was attributed to the increase in mobility and number density of charge carriers in the electrolyte from 6.63 × 10−9 cm2 V−1 s−1 to 1.25 × 10−6 cm2 V−1 s−1 and from 4.00 × 1020 cm−3 to 2.68 × 1021 cm−3, respectively. The electrolyte conductivity is seen to decrease as LiTf salts were added more than 40 wt% concentration due to the decrease of charge carrier mobility to 8.58 × 10−7 cm2 V−1 s−1. The variation of conductivity obtained in this work is dominantly influenced by the mobility of charge carriers in the electrolyte as proven from the Fourier transform infrared approach.

Conductivity Studies of Epoxidized PMMA Grafted Natural Rubber Doped Lithium Triflate Gel Polymer Electrolytes

A gel polymer electrolytes (GPEs) comprising of 62.3 mol% of epoxidized-30% poly(methyl methacrylate) grafted natural rubber (EMG30) as a polymer host, LiCF3SO3 as a dopant salt and ethylene carbonate (EC) as a plasticizer was prepared by solution-casting technique. The effect of plasticizer on the EMG30- LiCF3SO3 on the ionic conductivity is explained in terms of the plasticizer loading of the film. The temperature dependence of the conductivity of the polymer films obeys the Vogel-Tamman-Fulcher (VTF) relationship. The ionic transference number is calculated using Wagner’s polarization technique shows that the conducting species are predominantly due ions and hence showed the system is an ionic conductor. Surface morphological analysis showed the sample with the highest conductivity exhibited most homogenous in nature.

Ion Transport Mechanism in Flexible PMMAIL/LiTf Films

Acrylates such as poly (methyl methacrylate) (PMMA) has been widely studied as polymer electrolyte film due to its good mechanical stability towards lithium electrode. However, commercial PMMAs even at high molecular weight are not able to produce flexible films due to their polar nature that prone to form interchain crosslinking via hydrogen bonding. Therefore, the formation of hydrogen bonding was hindered by incarcerating ionic liquid (IL) of 1-methyl-3-pentamethyldisiloxymethylimidazolium bis(trifluoromethylsulfonyl)imide, [(SiOSi)C1C1im] [NTf2] during free radical polymerization of MMA. Interestingly, the synthesized PMMA containing IL (PMMAIL) produced flexible and free standing films with ionic conductivity of ~10-7 S cm-1. Though the ionic conductivity obtained is comparable with other doped PMMA film electrolytes that had been studied, it is still considered as low for application in energy storage devices. As an alternative, in this study, lithium triflate (LiTf) salt was added into the PMMAIL system and the highest ionic conductivity obtained was 2.65 ×10-4 S cm-1 with addition of 30 wt.% LiTf at ambient temperature. The temperature dependence conductivity and AC conductivity behaviour of PMMAIL/LiTf were further investigated in order to fully understand the ion transport mechanism that occurred in the system. It was found that the PMMAIL/LiTf system fits the Arrhenius behaviour and Correlated Barrier Hopping (CBH) model.