Understanding the Role of Solvents on the Morphological Structure and Li-Ion Conductivity of Poly(vinylidene fluoride)-Based Polymer Electrolytes

Zhou, Chengtian; Bag, Sourav; Lv, Bowen; Thangadurai, Venkataraman

doi:10.1149/1945-7111/ab7c3a

Cited by 54 publications

(41 citation statements)

References 50 publications

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“…Therefore, these relaxation processes may also become particularly relevant in the conductivity spectrum. Studies on PVDF-based polymer electrolytes without the content of ionic liquids 58,61 showed that the concentration and type of solvent, together with the drying process, affect the morphology, structure and electrical conductivity. The ionic conductivity is related to the quantity of the trapped solvent (crystallinity of PVDF); thus, the drying process led to a decrease in ionic conductivity 58 .…”

Section: Resultsmentioning

confidence: 99%

The effect of thermal treatment on ac/dc conductivity and current fluctuations of PVDF/NMP/[EMIM][TFSI] solid polymer electrolyte

Sedlák

Gajdoš

Macků

et al. 2020

Sci Rep

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The experimental study deals with the investigation of the effect of diverse crystallinity of imidazolium ionic-liquid-based SPE on conductivity and current fluctuations. The experimental study was carried out on samples consisting of [EMIM][TFSI] as ionic liquid, PVDF as a polymer matrix and NMP as a solvent. After the deposition, the particular sample was kept at an appropriate temperature for a specific time in order to achieve different crystalline forms of the polymer in the solvent, since the solvent evaporation rate controls crystallization. The ac/dc conductivities of SPEs were investigated across a range of temperatures using broadband dielectric spectroscopy in terms of electrical conductivity. In SPE samples of the higher solvent evaporation rate, the real parts of conductivity spectra exhibit a sharper transition during sample cooling and an increase of overall conductivity, which is implied by a growing fraction of the amorphous phase in the polymer matrix in which the ionic liquid is immobilized. The conductivity master curves illustrate that the changing of SPEs morphology is reflected in the low frequency regions governed by the electrode polarization effect. The dc conductivity of SPEs exhibits Vogel–Fulcher–Tammann temperature dependence and increases with the intensity of thermal treatment. Spectral densities of current fluctuations showed that flicker noise, thermal noise and shot noise seems to be major noise sources in all samples. The increase of electrolyte conductivity causes a decrease in bulk resistance and partially a decrease in charge transfer resistance, while also resulting in an increase in shot noise. However, the change of electrode material results in a more significant change of spectral density of current fluctuations than the modification of the preparation condition of the solid polymer electrolyte. Thus, the contact noise is considered to contribute to overall current fluctuations across the samples.

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Section: Resultsmentioning

confidence: 99%

The effect of thermal treatment on ac/dc conductivity and current fluctuations of PVDF/NMP/[EMIM][TFSI] solid polymer electrolyte

Sedlák

Gajdoš

Macků

et al. 2020

Sci Rep

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“…DMF is commonly used to prepare polyvinylidene difluoride (PVDF)-based polymer electrolytes via the solvent casting method. Following this process, DMF has been shown to be absorbed inside the polymer where it functions as a plasticizer resulting in increased ionic conductivity ( Zhou et al., 2020 ). Zhou et al.…”

Section: Impact Of Absorbed Dimethylformamide On Polymer Electrolytesmentioning

confidence: 99%

“…This was attributed to the decomposition of the polymer electrolyte. However, mass loss below 300°C was attributed to the evaporation of absorbed solvents ( Zhou et al., 2020 ). The mass percent of absorbed solvents (relative to the total polymer mass) in these samples following drying at 60°C and at 80°C for various time periods, determined based on the TGA data, is presented in Table 1 .…”

Section: Impact Of Absorbed Dimethylformamide On Polymer Electrolytesmentioning

confidence: 99%

“…Solvent content was somewhat correlated with ionic conductivity in these samples as drying at 80°C resulted in lower conductivities than drying at 60°C for all electrolytes ( Figure 5 ). Also, drying for additional days at each temperature did not result in significant changes in either ionic conductivity of solvent content ( Zhou et al., 2020 ). However, the absorbed solvent content did not correlate with the order of conductivities of the individual electrolytes ( Figure 5 ).…”

Section: Impact Of Absorbed Dimethylformamide On Polymer Electrolytesmentioning

confidence: 99%

“…The DMA-containing electrolyte, which contained the most solvent at both drying temperatures, only had the highest conductivity after drying at 60°C ( Zhou et al., 2020 ). The DMF-containing electrolyte, which contained the least amount of solvent at both drying temperatures, was the second most conductive sample after drying at 60°C ( Zhou et al., 2020 ).

Figure 5 Impact of Solvent Type, Drying Temperature, and Drying Time on Ionic Conductivity in PVDF-LiTFSI Films Ionic conductivity of PVDF-LiTFSI films prepared with DMA, DMSO, NMP, and DMF after drying at 60 and 80°C for several days.…”

Section: Impact Of Absorbed Dimethylformamide On Polymer Electrolytesmentioning

confidence: 99%

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The Impact of Absorbed Solvent on the Performance of Solid Polymer Electrolytes for Use in Solid-State Lithium Batteries

et al. 2020

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Summary The effects of solvent absorption on the electrochemical and mechanical properties of polymer electrolytes for use in solid-state batteries have been measured by researchers since the 1980s. These studies have shown that small amounts of absorbed solvent may increase ion mobility and decrease crystallinity in these materials. Even though many polymers and lithium salts are hygroscopic, the solvent content of these materials is rarely reported. As ppm-level solvent content may have important consequences for the lithium conductivity and crystallinity of these electrolytes, more widespread reporting is recommended. Here we illustrate that ppm-level solvent content can significantly increase ion mobility, and therefore the reported performance, in solid polymer electrolytes. Additionally, the impact of absorbed solvents on other battery components has not been widely investigated in all-solid-state battery systems. Therefore, comparisons will be made with systems that use liquid electrolytes to better understand the consequences of absorbed solvents on electrode performance.

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Significant Enhancement in the Thermoelectric Properties of Ionogels through Solid Network Engineering

Liu

Cheng

et al. 2021

Adv Funct Materials

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Thermoelectric (TE) materials are significant for sustainable development because they can be used to directly harvest heat into electricity. Recently, ionic TE materials emerged as very promising materials mainly due to their high thermovoltage that can be higher than the Seebeck coefficient of electronic TE materials by 2-3 orders in magnitude. However, their conductivity is very low. Here, the significant improvement in the ionic conductivity and thus the overall TE properties of ionogels is reported by engineering their solid networks, which immobilize the ionic liquid in the ionogels. An antisolvent of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) is added into the acetone solution of 1-ethyl-3-methylimidazolium dicyanamide (EMIM:DCA) that is an ionic liquid and PVDF-HFP prior to the ionogel formation. This can significantly change the solid networks formed by PVDF-HFP and thus the microstructure of the EMIM:DCA/PVDF-HFP ionogels, thereby facilitating ionic transport. As a result, the ionic conductivity of the ionogels can be increased from 7.0 to 17.6 mS cm −1 . The ionogels can exhibit a high ionic figure of merit (ZT i ) of 1.8 with the ionic Seebeck coefficient of 25.4 mV K −1 and the thermal conductivity of 0.190 W m −1 K −1 . This is the highest recorded ZT i value for ionic conductors.

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Understanding the Role of Solvents on the Morphological Structure and Li-Ion Conductivity of Poly(vinylidene fluoride)-Based Polymer Electrolytes

Cited by 54 publications

References 50 publications

The effect of thermal treatment on ac/dc conductivity and current fluctuations of PVDF/NMP/[EMIM][TFSI] solid polymer electrolyte

The effect of thermal treatment on ac/dc conductivity and current fluctuations of PVDF/NMP/[EMIM][TFSI] solid polymer electrolyte

The Impact of Absorbed Solvent on the Performance of Solid Polymer Electrolytes for Use in Solid-State Lithium Batteries

Significant Enhancement in the Thermoelectric Properties of Ionogels through Solid Network Engineering

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