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Author: search.filters.author.Sivasubramanian, S.C.Subject: search.filters.subject.Electrical transport

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    Ionic liquid composites with garnet-type Li6. 75Al0. 25La3Zr2O12: Stability, electrical transport, and potential for energy storage applications
    (Elsevier, 2024-04) Dalvi, Anshuman; Sivasubramanian, S.C.
    Garnet composites with ionic liquid dispersion have been prepared for electrolytic applications. Various ionic liquids (ILs) in small amounts were added to garnet type Li6.75Al0.25La3Zr2O12 (LALZO) to improve its ionic conductivity and electrode-electrolyte interfacial compatibility. The optimal composition having ∼6 wt% EMIM BF4 in LALZO showed a high ionic conductivity of 6 × 10-4 Ω-1cm-1 at room temperature, which is almost two orders of magnitude higher than the pristine garnet pellet. Such a high conductivity is attributed to the alteration of the ionic liquid-garnet interface by a weak non-uniform chemisorption. The thermal stability of the composites was confirmed by high-temperature X-ray diffraction, thermogravimetric analysis, differential scanning calorimetry (DSC), and dynamic electrical transport measurements, which suggested their stability at least up to 200 °C. The electrochemical performance of the composite was evaluated by assembling 2032-type LFP//LALZO-IL//Li cell, which displayed promising candidature for energy storage applications.
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    Preparation and characterization of novel solid electrolytes based on [EMIM] BF4 and lithium nitrate confined silica gels
    (Elsevier, 2019-11) Sivasubramanian, S.C.; Dalvi, Anshuman
    Novel ionic liquid ([EMIM]BF4) and lithium nitrate confined silica gel composites have been prepared via hydrolytic sol-gel process and found to exhibit electrical conductivity up to 10−4 Ω−1cm−1 in the temperature range 150–300 °C. The composites are thermally stable at this temperature range and measurements are repeatable. Powder X-ray diffraction patterns suggest that the composites are amorphous in nature. FE-SEM (EDS elemental mapping) and DSC measurements further confirm IL confinement in the matrix. Electrical conductivity (150–300 °C) has been studied as a function of IL and Li+ ion content. The samples with no IL content are essentially electronic in nature. Addition of IL in small amounts (1 mol%) enhances the total conductivity at least by an order of magnitude. Further addition of salt (LiNO3) enhances ionic transport by orders of magnitude. The electronic conductivity and ionic mobility along with OCV measurements on cells of type Li/composite/LiCoO2 suggests facilitation of Li+ ion transport in presence of IL in small amount. However, further increasing the content of IL in the composition while keeping the salt ion concentration same, does not improve conductivity, rather reduces it. This complex behavior may be due to possibility of Li+ ions forming complex with IL anion and further investigations are required in this regard. Preliminary findings suggest that these materials have good potential for their applications in all-solid-state supercapacitors.