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Evaluation of lithium ion conduction in PAN/PMMA-based polymer blend electrolytes for Li-ion battery applications

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Abstract

Polymer blend electrolytes composed of poly(acrylonitrile) (PAN) and poly(methyl methacrylate) (PMMA) as host polymers and lithium perchlorate as a salt were prepared by solution casting technique. The electrolytes were prepared for different ratios of host polymers with standard weight ratio of the ionic salt (LiClO4). Among the different concentrations, the polymer electrolyte film containing PAN/PMMA (75:25 wt.%) was found to be a suitable candidate for the battery applications on the basis of ionic conductivity and thermal stability. Complexation, structural reorganizations and ionic conductivity as a function of temperature were studied using X-ray diffraction analysis, Fourier transform infrared, and ac impedance analysis, respectively. Thermal stability of the electrolyte film having maximum ionic conductivity was also studied using thermogravimetric analysis.

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... (1492 cm −1 ) compared to (1499 cm −1 ) PMMA [32]. Similarly, the vibrational deformation frequency of OCH 3 group shows decrease in value for Z2 (1372 cm −1 ) and slight increase for Z5 (1388 cm −1 ) when compared to PMMA (1387 cm −1 ) [31]. ...
... The increase in carbonyl stretching frequency for samples Z2 and Z5 (~1730 cm −1 ) when compared to PMMA (1711 cm −1 ) is due to the presence and interaction of plasticizers EC and PC along with polymer blend containing PMMA with Lithium ion [31]. There is not much change in the C=C ring stretching and C-H ring bending vibrations in samples Z2 and Z5 compared to SAN [32]. This indicates that the electron rich aromatic ring of poly(styrene-co-acrylonitrile) does not interact with either lithium ion or ZrO 2 nanofiller. ...
... Ionic conductivity increases with increasing content of ZrO2 nano-filler up to 6 wt% and decreases further (Fig. 4). The maximum ionic conductivity of 2.32 × 10 −4 S cm −1 at room temperature and 6.59 × 10 −4 S cm −1 at 70°C is obtained for sample Z2 (6 wt% ZrO 2 ) respectively and is comparable with similar systems in literature [20,31,32,36]. The increase in ionic conductivity is due to increase in charge carriers in the polymer matrix of the electrolyte [41,42]. ...
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The plasticized composite solid polymer electrolytes (CSPE) involving polymer blends poly(methyl methacrylate)-poly(styrene-co-acrylonitrile) (PMMA-SAN), plasticizers ethylene carbonate (EC), and propylene carbonate (PC) with lithium triflate (LiCF3SO3) as salt and varying concentration of composite nano-filler zirconium oxide (ZrO2) is prepared by solution casting technique using THF as solvent. The powder X-ray diffraction (XRD) studies reveal amorphous nature of the CSPE samples. Fourier transform infrared (FT-IR) spectroscopy studies reveal interaction of Li+ ion with plasticizers, both C=O and OCH3 group of the PMMA, while nitrile group of SAN is inert. AC impedance and dielectric studies reveal that the ionic conductivity (σ), dielectric constant (ε’), and dielectric loss (ε”) of the prepared CSPE samples increase with increasing content of ZrO2 nano-filler up to 6 wt% and decrease with further additions. The temperature dependence of ionic conductivity follows Arrhenius relation and indicates ion-hopping mechanism. The sample Z2 (6 wt% ZrO2) with relaxation time τ of 8.13 × 10–7 s possess lowest activation energy (Ea = 0.23 eV) and highest conductivity (2.32 × 10–4 S cm−1) at room temperature. Thermogravimetric analysis (TGA) reveals thermal stability of highest conducting sample Z2 up to 321 °C after complete removal of residual solvent, moisture, and its impurities. Differential scanning calorimetric (DSC) studies reveal absence of glass transition temperature (Tg) corresponding to atactic PMMA for the CSPE Z2, while isotactic PMMA component shows Tg around 70 °C, which is due to increased interaction of filler with PMMA leading to change in its tacticity. Scanning electron microscopy (SEM) analysis reveals blending of PMMA/SAN polymers and lithium triflate salt. The incorporation of nano-filler ZrO2 leads to change in surface topology of polymer matrix. Rough surface of the CSPE Z2 leads to new pathway for ionic conduction leading to maximum ionic conductivity.
... Both two samples show the characteristic adsorption peaks of RAFT agent at 3433, 1675, 1384 and 1093 cm À 1 , which can be assigned to hydroxyl stretching vibration, C ¼O stretching vibration of carboxyl group, C(CH 3 ) 2 stretching vibration and C ¼ S, respectively [29,32]. For PAN macro-RAFT agent, the peak located at 2240 cm À 1 corresponds to symmetric C≡N stretching vibration, which is the characteristic peak of PAN [33]. After the MMA induced by PAN macro-RAFT agent, the peak for C ¼O stretching vibration of carbonyl group at 1730 cm À 1 was observed, which is the characteristic peak of -PMMA block [31]. ...
... FTIR was used to study the composition of polymer membrane [32]. The FTIR spectrum of hybrid polymer membrane is shown in Fig. 3, which displayed both the characteristic adsorption bands of PAN and PMMA as follows: the peaks at 2240 and 1250 were assigned to symmetrical C≡N and inplane symmetrical C-N stretching vibrations, respectively [33]. The vibration frequencies at 2930, 1727, 1446 and 1193 were attributed to CH 3 , C¼ O, O-CH 3 stretching and C-C-O vibration [33][34][35]. ...
... The FTIR spectrum of hybrid polymer membrane is shown in Fig. 3, which displayed both the characteristic adsorption bands of PAN and PMMA as follows: the peaks at 2240 and 1250 were assigned to symmetrical C≡N and inplane symmetrical C-N stretching vibrations, respectively [33]. The vibration frequencies at 2930, 1727, 1446 and 1193 were attributed to CH 3 , C¼ O, O-CH 3 stretching and C-C-O vibration [33][34][35]. The above result confirms that the prepared membrane combined the homopolymer of PAN and the triblock copolymer of PAN-b-PMMA-b-PAN [34]. ...
... Polymer blending technology is a promising method to regulate the crystallinity of PEO for improving Li-ion conductivity, thermal stability and electrochemical window. [26][27][28][29][30][31][32] In general, low glass transition temperature and good flexibility are necessary for the co-added polymers used as polymers for blending due to their high ionic conductivity. ...
... [33][34][35][36][37][38][39] Besides the polymer blending, the addition of nano-metal oxides such as SiO 2 to CPE can not only adjust the crystallinity of PEO, but also enhance its mechanical properties. 27,[36][37][38] Polysiloxanes, also known as silicones, have highly flexible backbones, with the barrier to bond rotation being only 0.8 kJ mol −1 , very low glass-transition energies (T g ) and high free volumes. 20,[39][40][41][42] It is well known that silicone is a renewable material and exhibits outstanding properties such as environmental friendliness, chemical stability and thermal stability. ...
Article
Solid-state lithium metal batteries have emerged as a promising alternative to exist liquid Li-ion batteries and power the future storage market considering the higher energy outputs and better safety. Among various solid electrolyte, polymer electrolytes have received more attention due to their potential advantages, including wide electrochemical windows, ease of processing, low interface impedance and low cost. Polymeric electrolyte based on poly (ethylene oxide) (PEO) as a well-known polymer matrix has been extensively studied because of its highly flexible EO segments in the amorphous phase that can provide channels for lithium ion transport. However, obtaining a PEO-based solid electrolyte with high Li ion conductivity and without sacrificing mechanical strength is still a huge challenge. In this study, the polymethylhydrogen-siloxane (PMHS) with low glass transition temperature and good flexibility was blended into the PEO to optimize the ion transportion by solution casting technique. The hybrid electrolyte membrane with 40% PMHS exhibited high ionic conductivity(2.0×10-2 S cm-1 at 80 °C), large electrochemical windows (5.2 V), high degree flexibility, and thermal stability. When assembling a Li/LiFePO4 battery, a reversible capacity close to 140 mA h g-1 (0.1 C) at 60 °C was delivered. In addition, a cell with this polymer electrolyte exhibits excellent stability. These results demonstrate that the solid polymer electrolyte systems are eligible for next-generation high energy density all-solid-state lithium ion batteries.
... The TG curve shows gradual weight loss of 9% up to 169 °C. This initial weight loss is due to the presence of solvent and little moisture while loading the sample [41]. The film is found to be stable from 169 to 333 °C with a weight loss of 6%, after which the sample undergoes drastic weight loss of 54% at 439 °C. ...
... The filler particles are not embedded into the system. The CSPE sample T5 (9 wt% TiO 2 ) shows surface morphology in which the presence of nano-filler TiO 2 and lithium triflate salt with the polymer electrolyte surface does not lead to heterogeneity of the polymer blend (Fig. 12b) [41]. The amorphous nature is retained thus enhancing ionic mobility and hence ionic conductivity. ...
Article
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The composite solid polymer electrolyte (CSPE) samples, comprising of poly(methylmethacrylate) (PMMA)/poly(styrene-co-acrylonitrile) (SAN)/ethylene carbonate (EC)/propylene carbonate (PC)/lithium trifluoromethanesulfonate (LiCF3SO3)/anatase-TiO2 as nano-filler (0, 5, 6, 7, 8 and 9 wt% for samples T0, T1, T2, T3, T4 and T5 respectively) were prepared by solution casting technique. Fourier transform infrared (FT-IR) spectral studies indicate the interaction of PMMA and plasticizers (EC, PC) with Lithium ion and nano-filler TiO2 in samples. From AC impedance studies ionic conductivity, dielectric constant increase with increase in the concentration of nano-filler TiO2 up to 9 wt%. The sample T5 shows lowest activation energy (Ea) of 0.14 eV, very short relaxation time (τ) of 1.49 × 10⁻⁷ s and exhibits maximum ionic conductivity of 1.05 × 10⁻⁴ S cm⁻¹ at room temperature. The conductivity-temperature dependence studies showed that the conductivity of all samples depict Arrhenius behaviour suggesting ion-hopping mechanism. Dielectric studies reveal ion conducting nature of CSPE samples. Thermogravimetric analysis indicate the thermal stability of CSPE sample T5 up to 333 °C with maximum degradation at 388 °C. DSC studies reveal absence of glass transition temperature (Tg) of atactic component of PMMA in CSPE sample T5 indicating amorphous nature. X-ray diffraction patterns shows shift in the position of peaks confirming the complex formation of the PMMA-SAN-EC-PC-LiCF3SO3-TiO2 system. SEM analysis indicates that the presence of lithium salt and filler TiO2 on polymer host does not lead to heterogenous polymer blend thus retaining its amorphous nature.
... Polyacrylonitrile (PAN) has been studied as a separator material and PAN-based separators show promising properties, including high ionic conductivity, good thermal stability, high electrolyte uptake and good compatibility, with Li metal [18]. Polymethylmethacrylate (PMMA) has also been used as a separator material due to its good compatibility with Li and high affinity to liquid electrolyte [19,20]. Blending PAN and PMMA can potentially lead to new separators with enhanced microstructure, porosity and electrochemical properties that cannot be achieved by single-component polymer membranes. ...
... Blending PAN and PMMA can potentially lead to new separators with enhanced microstructure, porosity and electrochemical properties that cannot be achieved by single-component polymer membranes. Different blend separators including PVDF/PMMA-co-PEGMA microporous separators [21], PVDF-co-HFP/PAN microporous membranes [22], PVDF/PMMA microporous membranes [19,23], electrospun PVDF/PAN membranes [18], and electrospun PVDF-HFP/PMMA [24] have been reported so far, and results demonstrated that blend separators have the advantages of improved electrolyte uptake, ionic conductivity, and cycling performance. In this work, centrifugal spinning was utilized to produce PAN/PMMA blend membranes for use as high-performance separator for Li-ion batteries. ...
Article
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Electrospun nanofiber membranes have been extensively studied as separators in Li-ion batteries due to their large porosity, unique pore structure, and high electrolyte uptake. However, the electrospinning process has some serious drawbacks, such as low spinning rate and high production cost. The centrifugal spinning technique can be used as a fast, cost-effective and safe technique to fabricate high-performance fiber-based separators. In this work, polymethylmethacrylate (PMMA)/polyacrylonitrile (PAN) membranes with different blend ratios were produced via centrifugal spinning and characterized by using different electrochemical techniques for use as separators in Li-ion batteries. Compared with commercial microporous polyolefin membrane, centrifugally-spun PMMA/PAN membranes had larger ionic conductivity, higher electrochemical oxidation limit, and lower interfacial resistance with lithium. Centrifugally-spun PMMA/PAN membrane separators were assembled into Li/LiFePO4 cells and these cells delivered high capacities and exhibited good cycling performance at room temperature. In addition, cells using centrifugally-spun PMMA/PAN membrane separators showed superior C-rate performance compared to those using microporous polypropylene (PP) membranes. It is, therefore, demonstrated that centrifugally-spun PMMA/PAN membranes are promising separator candidate for high-performance Li-ion batteries.
... Supercapacitors have emerged as most promising sustainable energy storage devices due to long cycle life, high power density, and ultra-fast charging/ discharging time [4][5][6][7][8]. Moreover, due to the burgeoning research area of carbon-based nanomaterials such as graphene, nanotubes, nanodots, and quantum dots, the intensive development of supercapacitor energy storage devices has also been increased [9][10][11]. Studies reveal many research works have been focused on the synthesis of materials and their composites with other hybrids demonstrating high capacitance, wide potential window, lesser impedance, and good capacitive retention [12]. ...
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Herein, we demonstrate the fabrication of highly capacitive activated carbon (AC) using a bio-waste Kusha grass ( Desmostachya bipinnata ), by employing a chemical process followed by activation through KOH. The as-synthesized few-layered activated carbon has been confirmed through X-ray powder diffraction, transmission electron microscopy, and Raman spectroscopy techniques. The chemical environment of the as-prepared sample has been accessed through FTIR and UV–visible spectroscopy. The surface area and porosity of the as-synthesized material have been accessed through the Brunauer–Emmett–Teller method. All the electrochemical measurements have been performed through cyclic voltammetry and galvanometric charging/discharging (GCD) method, but primarily, we focus on GCD due to the accuracy of the technique. Moreover, the as-synthesized AC material shows a maximum specific capacitance as 218 F g ⁻¹ in the potential window ranging from − 0.35 to + 0.45 V. Also, the AC exhibits an excellent energy density of ~ 19.3 Wh kg ⁻¹ and power density of ~ 277.92 W kg ⁻¹ , respectively, in the same operating potential window. It has also shown very good capacitance retention capability even after 5000th cycles. The fabricated supercapacitor shows a good energy density and power density, respectively, and good retention in capacitance at remarkably higher charging/discharging rates with excellent cycling stability. Henceforth, bio-waste Kusha grass-derived activated carbon (DP-AC) shows good promise and can be applied in supercapacitor applications due to its outstanding electrochemical properties. Herein, we envision that our results illustrate a simple and innovative approach to synthesize a bio-waste Kusha grass-derived activated carbon (DP-AC) as an emerging supercapacitor electrode material and widen its practical application in electrochemical energy storage fields.
... Figure 4a shows the temperature-dependent ionic conductivity. It is evident that the rise in temperature contributes to the improvement in electrolyte conductivity from Fig. 4a which may be due to the promotion on thermal movement of ions and polymer chains by the volume expansion of the polymer during heating [45]. Calculated in Eq. (4), the corresponding ionic conductivity of the Celgard 2320 separator and PM-0, PM-1, PM-2, and PM-3 membranes at 26°C are 0.84, 1.43, 1.55, 2.03, and 2.18 mS cm −1 , respectively. ...
Article
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A gel polymer electrolyte based on the blending membranes of poly(vinylidene fluoride) (PVDF)/polymethyl methacrylate (PMMA) has been manufactured through the non-solvent-induced phase separation (NIPS) method. Its physical and electrochemical properties are characterized, and the blending compatibility of the PVDF/PMMA polymer is demonstrated by thermodynamic analysis. The increase in PMMA content has a great effect on surface morphologies of the PVDF/PMMA blending membranes, especially in terms of PM-3 (membrane with the weight ratio of PVDF/PMMA = 6:4). The PM-3 membrane presents satisfactory ionic conductivity (2.18 mS cm−1 at 26 °C), acceptable thermal stability, and superior compatibility with lithium. In addition, its cycle performance (130.7 mAh g−1 after circulating 200 cycles at 1 C) and rate capability (133.3 mAh g−1 at 4 C) are superior to those of the Celgard 2320 (PP/PE/PP) separator. It is indicated that the PVDF/PMMA blending membrane is promising for the fabrication of rechargeable lithium-ion battery.
... Helan et al. have been reported outstanding thermal stability up to 230 ? C for PAN/PMMA blends, but with quite low ionic conductivity, of the order of 2 ? 10 ?7 S cm ?1 [18]. Very interesting electrical behavior and dimensional stability have been obtained by Choi et al. on PEO-PAN blend gel electrolytes, despite no evidence regarding mechanical resistance being provided [19]. ...
Article
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Composite gel polymer electrolytes (GPEs) based on organo-modified montmorillonite clays have been prepared and investigated. The organo-clay was prepared by intercalation of CTAB molecules in the interlamellar space of sodium smectite clay (SWy) through a cation-exchange reaction. This was used as nanoadditive in polyacrylonitrile/polyethylene-oxide blend polymer, lithium trifluoromethanesulphonate (LiTr) as salt and a mixture of ethylene carbonate/propylene carbonate as plasticizer. GPEs were widely characterized by DSC, SEM, and DMA, while the ion transport properties were investigated by AC impedance spectroscopy and multinuclear NMR spectroscopy. In particular, 7Li and 19F self-diffusion coefficients were measured by the pulse field gradient (PFG) method, and the spin-lattice relaxation times (T1) by the inversion recovery sequence. A complete description of the ions dynamics in so complex systems was achieved, as well as the ion transport number and ionicity index were estimated, proving that the smectite clay surfaces are able to “solvatate” both lithium and triflate ions and to create a preferential pathway for ion conduction.
... A growing number of such hybrid materials and approaches have been developed by integration of a batterytype electrode and a capacitive electrode in a single device [7][8][9][10][11][12][13][14]. Battery-type electrodes such as lithium titanate (Li 4 Ti 5 O 12 ) [15], lithium manganese oxide (LiMn 2 O 4 ) [16], silicon (Si) [17], nickel oxyhydroxide (NiO(OH)) [18,19], lead dioxide (PbO 2 ) [20], transition metal oxides [21,22], and electroactive polymers [23] have been reported. ...
Article
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The integration of a battery-type electrode and of a capacitor-type electrode in a single device by proper design is an effective strategy in developing energy storage devices with high energy and power densities. Herein, we present a battery-supercapacitor hybrid device using metallic zinc as anode, a biodegradable ionic liquid (IL) as electrolyte, and graphite as cathode. The recently developed choline acetate ([Ch]OAc) biodegradable IL-based electrolyte enables reversible deposition/stripping of Zn(II). Spongy-like Zn with a high surface area is obtained, which allows fast charge/discharge at high rates. The adsorption/desorption of ions on the surface of the graphite cathode and intercalation/deintercalation of anions into/from the graphite layers occur at the graphite cathode. Raman spectra and X-ray photoelectron reveal the intercalation of IL into and the adsorption of IL on the graphite. Highly reversible adsorption/desorption of ions on the surface of the graphite electrodes in the [Ch]OAc-based electrolyte was demonstrated by a symmetric cell. The Zn/graphite hybrid device delivers an energy density of 53 Wh kg⁻¹ at a power density of ~ 145 W kg⁻¹ and 42 Wh kg⁻¹ at ~ 400 W kg⁻¹. The hybrid device also exhibits a long cycle life with ∼ 86% specific capacitance retained after 1000 cycles at a current density of 0.5 A g⁻¹. The combination of well-available zinc, inexpensive graphite, and a biodegradable IL electrolyte in a cell could open new avenues for sustainable energy applications. Graphical abstractᅟ
... In the aspect of materials, these electrolyte membranes are made of similar polymer materials with non-electrolyte membranes, but they are incorporated with ionically conductive components, e.g. lithium salts to form solid polymer electrolytes [524][525][526][527] or liquid lithium-based electrolyte such as lithium hexafluorophosphate and lithium polyvinyl alcohol oxalate borate to form gel polymer electrolytes [528][529][530][531][532][533][534][535][536]. Recently, ion exchange membranes with lithiated perfluorinated sulfonic groups, swollen with organic solvents, have been investigated [537][538][539], demonstrating high thermal and mechanical stability and good interfacial compatibility with the electrodes. ...
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Water and energy have always been crucial for the world’s social and economic growth. Their supply and use must be sustainable. This review discusses opportunities for membrane technologies in water and energy sustainbility by analyzing their potential applications and current status; providing emerging technologies and scrutinizing research and development challenges for membrane materials in this field.
... This results is in agreement with the results of the free volume and positron annihilaton studies in PEO:NH 4 ClO 4 systems [12]. Knowing the facts about PMMA system some literature are also exist in which researchers are applied it in battery application [26,27]. ...
Article
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The ionic conductivity, dielectric constant and X-ray diffraction (XRD) studies are reported on the solution casted film of [xPEO + (100-x) PMMA]:NH4ClO4 for x= 0-100 weight percent. The NH4ClO4 crystallizes out in the films with large amounts of polymethyl methacrylate (PMMA). However, addition of a small amount of PMMA in PEO: NH4ClO4 matrix enhances the ionic conductivity. The thermally activated conductivity variation is explained in terms of the electrolyte dissociation theory.
... Blending different polymers may help address these issues. Flora et al. 271 reported PAN/PMMA based gel polymer electrolytes by the solution casting technique and their results showed that the electrolyte containing PAN/PMMA (75 : 25 wt%) was thermally stable up to 200 C. Subramania et al. 272 and Gopalan et al. 273 blended PAN with PVDF to prepare gel polymer electrolytes, and it was found that the introduction of PAN led to reduced dendrite growth, higher mechanical stability and improved interfacial characteristics compared with PVDF based electrolytes. 273 278 Composite electrolytes can be obtained by the introduction of inorganic llers into solid polymer electrolytes or gel polymer electrolytes. ...
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In this paper, the recent developments and their characteristics of membrane separators for lithium-ion batteries are reviewed. In recent years, there have been intensive efforts to develop advanced battery separators for rechargeable lithium-ion batteries for different applications such as portable electronics, electric vehicles, and energy storage for power grids. Separator is a critical component of lithium-ion batteries since it provides a physical barrier between the positive and negative electrodes in order to prevent electrical short circuits. The separator also serves as the electrolyte reservoir for the transport of ions during the charging and discharging cycles of a battery. The performance of lithium-ion batteries is greatly affected by the materials and structure of the separators. This paper introduces the requirements of battery separators and the structure and properties of four important types of membrane separators which are microporous membranes, modified microporous membranes, non-woven mats, and composite membranes. Each separator type has inherent advantages and disadvantages which influence the performance of lithium-ion batteries. The structures, characteristics, manufacturing, modification, and performance of separators are described in this review paper. The outlooks and future directions in this research field are also given.
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The current all-solid-state battery (ASSB) technology must stride through meticulous research work to reap the much-sought benefits of high energy density, stable cycling life and economical fabrication of ASSBs for large scale applications. Among all the prevailing scientific challenges, low room temperature ionic conductivity and interfacial impedance are the major roadblocks which need to be addressed before introducing them in large scale application in the high-power devices such as electric vehicles. Herein, we briefly discuss the background and the advances of polymeric and composite solid electrolyte systems with their fundamental ion transport mechanism, followed by a discussion on understanding the chemistry of various interfaces and interphases phenomena, various types of (in)stability issues, other bottleneck and challenging parameters, and the proposed solution to these in cell design strategies. In addition, this review also critically introspects the current measurement methods for collecting and reporting data on the ionic conductivity and reliability of the acquired data. The insights into these aspects will not only enlighten the readers about the recent trends in polymeric solid electrolytes but also will assist determining the correct type of measurement methods and the right cell design strategies.
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The development of gel polymer electrolytes (GPEs) is considered to be an effective strategy to drive practical applications of high-voltage lithium metal batteries (HLMBs). However, rare GPEs that can satisfy the demands of HLMBs have been developed because of the limited compatibility with lithium anodes and high-voltage cathodes simultaneously. Herein, a novel strategy for constructing polymer matrixes with a customized frontier orbital energy for GPEs is proposed. The as-investigated polymer matrix (P(CUMA-NPF6))-based GPE (P(CUMA-NPF6)-GPE) obtained via in situ random polymerization delivers a wide voltage window (0-5.6 V vs Li+/Li), large lithium-ion transference number (tLi+, 0.61), and superior electrode/electrolyte interface compatibility. It is to be noted that such a tLi+ of P(CUMA-NPF6)-GPE, which is one of the largest tLi+ among high-voltage GPEs in a fair comparison, results from the high dissociation of lithium salts and effective anion immobilization abilities of P(CUMA-NPF6). Ultimately, the as-assembled HLMB delivers more enhanced cycle performance than its counterpart of commercial liquid electrolytes. It is also demonstrated that P(CUMA-NPF6) can scavenge the active PF5 intermediate generated in the electrolyte at the anode side, thus suppressing the PF5-mediated decomposition reaction of carbonates. This work will enlighten the rational structure design of GPEs for HLMBs.
Conference Paper
In this work, the effect of inert fillers on poly(methyl methacrylate) (PMMA) composite polymer electrolytes (CPEs) are investigated. The PMMA–LiCF3SO3–EC–Al2O3 composite polymer electrolytes were prepared using solution casting method at room temperature. Lithium trifluoromethanesulfonate (LiCF3SO3) is used as the electrolyte salt which plays an important role in Li ion transfer. In order to soften the polymer matrix, ethylene carbonate (EC) is introduced into the CPEs to help in the disassociation of lithium salt ion pairs. Nano sized aluminium oxide (Al2O3) is then incorporated to enhance mechanical strength and ionic conductivity of the polymer electrolyte. The optimum of 2 wt.% 50 nm Al2O3 was added into the PMMA polymer electrolyte sample. Through Electrochemical Impedance Spectroscopy (EIS) measurements, the highest ionic conductivity at room temperature is determined as 1.52×10-4 S/cm. FTIR spectra analysis showed CH2 twisting mode at 1383.43 cm-1, C=O stretching mode at 1721.56 cm-1 which proven the interaction between host polymer and lithium salt and CH3 stretching mode at 2981.34 cm-1. XRD analysis had also been performed to study the structural behaviour of the PMMA polymer electrolyte. The intense peak at position 2θ angle of 15.04°, 30.92° and 45.58° occur upon interaction with Al2O3. Lastly, the surface morphology is studied through SEM+EDX analysis.
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Plasticized polymer electrolytes comprising of ethylene carbonate as the plasticizing agent in poly (vinyl chloride) [PVC]–poly (butyl methacrylate) [PBMA] blended polymer electrolytes were prepared by solution casting technique. Complex formation, structural elucidation, conductivity, dielectric parameters (Ɛ′, Ɛ″, M′, and M″), thermal stability, and surface morphology are brought out from FTIR, XRD, ac impedance analysis, dielectric studies, thermogravimetry/differential thermal analysis, and scanning electron microscopic studies, respectively. Polymer electrolytes are found to exhibit higher ionic conductivity at higher concentration of plasticizer at the cost of their mechanical stability. Conductivity of 1.879 × 10⁻⁴ S cm⁻¹ is exhibited by the polymer electrolyte consisting of 69% of plasticizer with appreciable thermal stability up to 523 K. Temperature and frequency dependence of conductivity is found to follow Vogel Tammann Fulcher relation and Jonscher power law, respectively. Real and imaginary parts of dielectric constants are found to decrease with increase in frequency which could be due to the electrode polarization effect.
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Poly(vinyl chloride) (PVC)—poly(butyl methacrylate) (PBMA) blended polymer electrolytes with lithium perchlorate (LiClO4) as the complexing salts are prepared by solution casting technique. The addition of PBMA into PVC matrix is found to induce considerable changes in physical and electrical properties of the polymer electrolytes. Addition of PBMA into PVC matrix is found to increase the conductivity by two orders of magnitude (1.108 × 10−5 S cm−1) when compared with that of the pristine PVC polymer electrolyte (10−7 S cm−1). Structural, thermal, mechanical, morphological, and polymer–salt interactions are ascertained from X-ray diffraction (XRD), thermogravimetry/differential thermal analysis (TG/DTA), mechanical analysis, scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR) respectively. A thermal stability upto 250 °C is asserted from the TG/DTA analysis. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44939.
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Polymer electrolytes prepared by the complexation of lithium salts with poly(ethylene oxide) (PEO) and poly(vinylidene chloride-co-acrylonitrile) (PVdC-co-AN) will be of great use as separators in lithium polymer batteries. The amorphous nature of the blend electrolyte shows that the conductivity increases by the addition of lithium salts. The presence of C N and C = N in PVdC-co-AN are confirmed from the Fourier transform infrared studies. Among the various lithium salts studied, lithium trifluoro methane sulfonoimide [LiN(CF3SO2)(2)] based electrolyte exhibits the highest ionic conductivity of the order of 0.265 x 10(-5) Scm(-1) at room temperature. The sample having a maximum ionic conductivity PEO(80 wt%)/PVdC-co-AN(20 wt%)/LiN(CF3SO2)(2)(8 wt%) is supported by the lower optical band gap in UV-Visible analysis and low intensity in luminescence studies. Two and three dimensional topographic images of the above sample reveal the presence of micropores. Thermal stability of the prepared electrolytes is studied by thermo gravimetric/differential thermal analysis. Using differential scanning calorimetric analysis, the minimum glass transition temperature (30 degrees C) is observed for the sample doped with LiN(CF3SO2)(2). The cyclic voltammetric studies reveal the strong capacitive behavior of the prepared polymer electrolytes. The electrochemical stability windows for the prepared samples are observed using linear sweep voltammetry.
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Polymer blend electrolytes are prepared for various concentration of LiClO4 salt with the constant ratio of PAN and PMMA polymers using solution casting technique. The structural and complex formations of the basic constituents and their complexes are analyzed by XRD and FTIR spectroscopic techniques. The effect of salt concentration on the ionic conductivity and the temperature dependence of ionic conductivity in the range 302-373K have been studied using ac impedance spectroscopy analysis. The maximum ionic conductivity value is found to be of the order of 0.562 x 10-5 Scm-1 for the film containing PAN (75 wt.%) PMMA (25wt.%) with LiClO4 (wt.8%). The thermal behaviours of the films are ascertained from thermo gravimetric analysis and differential scanning calorimetry. The sample exhibits higher ionic conductivity has also been subjected to scanning electron microscopy inorder to study the micro structure of the electrolyte system.
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A new composite gel polymer electrolyte of nonwoven fabric (NWF) and methyl cellulose (MC) with good mechanical property and outstanding thermal and electrochemical stability is prepared by a simple and green casting process followed by absorbing liquid electrolyte. Its characteristics are investigated by scanning electron microscopy, FT-IR, thermogravimetric analysis (TGA). Due to the synergistic action between MC matrix and the NWF framework, the composite gel polymer electrolyte achieves higher ionic conductivity (0.29 mS cm-1) at ambient temperature and larger lithium ion transference number (0.34) than those (0.21 mS cm-1 and 0.27, respectively) for the conventional Celgard 2730 separator in 1mol L-1 LiPF6 electrolyte, and their activation energies are similar. In addition, the composite membrane shows better mechanical strength than the pure MC membrane. The evaporation rate of the liquid electrolyte at elevated temperature is much decreased. The assembled Li//LiFePO4 cell using this composite gel membrane exhibits better cycling retention and higher discharge capacity than those based on Celgard 2730 separator and pure MC gel membrane. These fascinating characteristics suggest that this unique composite gel polymer electrolyte can be used for lithium ion batteries with good performance and low cost.
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In lithium ion battery systems, the separator plays a key role with respect to device performance. Polymer composites and polymer blends have been frequently used as battery separators due to their suitable properties. This review presents the main issues, developments and characteristics of these polymer composites and blends for battery separator membrane applications. This review is divided into two sections regarding the composition of the materials: polymer composite materials, subdivided according to filler type, and polymer blend materials. For each category the electrolyte solutions, ionic conductivity and other relevant physical-chemical characteristics are described. This review shows the recent advances and opportunities in this area and identifies future trends and challenges.
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A new type of organic–inorganic hybrid polymer electrolyte based on poly(propylene glycol)-blockpoly( ethylene glycol)-block-poly-(propylene glycol)bis(2-aminopropyl ether), polyacrylonitrile (PAN), 3-(glycidyloxypropyl)trimethoxysilane (GLYMO) and 3-(aminopropyl)trimethoxysilane (APTMS) complexed with LiClO4 via the co-condensation of organosilicas was synthesized. The structural and electrochemical properties of the materials were systematically investigated by a variety of techniques including differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), multinuclear (13C, 29Si, 7Li) solid-state NMR, AC impedance, linear sweep voltammetry (LSV) and charge– discharge measurement. A maximum ionic conductivity value of 7.4 �x 10-�5 S cm�-1 at 30 �C and 4.6 �x 10-�4 S cm�-1 at 80 �C is achieved for the solid hybrid electrolyte. The 7Li NMR measurements reveal the strong correlation of the lithium cation and the polymer matrix, and the presence of two lithium local environments. After swelling in an electrolyte solvent, the plasticized hybrid membrane exhibited a maximum ionic conductivity of 6.4 x � 10-�3 S cm-�1 at 30 �C. The good value of the electrochemical stability window (�4.5 V) makes the plasticized hybrid electrolyte membrane promising for electrochemical device applications. The preliminary lithium ion battery testing shows an initial discharge capacity value of 123 mA h g�-1 and a good cycling performance with the plasticized hybrid electrolyte.
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Ionically conducting polymer membranes (polymer electrolytes) might enhance lithium-battery technology by replacing the liquid electrolyte currently in use and thereby enabling the fabrication of flexible, compact, laminated solid-state structures free from leaks and available in varied geometries. Polymer electrolytes explored for these purposes are commonly complexes of a lithium salt (Lix) with a high-molecular-weight polymer such as polyethylene oxide (PEO). But PEO tends to crystallize below 60 °C, whereas fast ion transport is a characteristic of the amorphous phase. So the conductivity of PEO-LiX electrolytes reaches practically useful values (of about 10-4S cm-1) only at temperatures of 60-80 °C. The most common approach for lowering the operational temperature has been to add liquid plasticizers, but this promotes deterioration of the electrolytes mechanical properties and increases its reactivity towards the lithium metal anode. Here we show that nanometre-sized ceramic powders can perform as solid plasticizers for PEO, kinetically inhibiting crystallization on annealing from the amorphous state above 60 °C. We demonstrate conductivities of around 10-4 S cm-1 at 50 °C and 10-5 S cm-1 at 30 °C in a PEO- LiClO4 mixture containing powders of TiO2 and Al2O3 with particle sizes of 5.8-13 nm. Further optimization might lead to practical solid-state polymer electrolytes for lithium batteries.
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Polymer blend electrolytes comprising of poly(vinyl acetate), poly(vinylidene fluoride-co-hexafluoropropylene), LiClO4, and EC-based plasticizer combinations (EC+PC, EC+GBL, EC+DMP, EC+DBP, EC+DEC) are prepared by solvent casting technique. Ionic conductivities of the electrolytes are determined by ac impedance studies in the temperature range 303–363K. Among the various combinations of plasticizers, EC+PC added complex exhibits maximum ionic conductivity of the order of 10−4Scm−1 and the temperature-dependent ionic conductivity plots seem to obey the VTF relation. The structural and complex formations of the prepared samples have been confirmed by X-ray diffraction analysis. DSC technique is used to study the thermal behaviour. The surface images of the sample having maximum ionic conductivity are analyzed with the help of SEM and AFM techniques. KeywordsPoly(vinyl acetate)–Ionic conductivity–Plasticizers–Atomic force microscopy–Scanning electron microscopy
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Ionic conductivities of plasticized poly(vinylchoride) (PVC)/poly(methylmethacrylate) (PMMA) blend electrolyte films containing two different lithium salts, viz., lithium tetrafluroborate (LiBF4) and lithium perchlorate (LiClO4) are studied using the AC impedance technique at 25°C, 40°C, 50°C and 60°C. A mixture of ethylene carbonate (EC) and propylene carbonate (PC) is used as the plasticizer. Pure PMMA and PMMA-rich phases exhibited better conductivity. The variation of ionic conductivity for different plasticizer contents and for different lithium salts is reported. The variation in film morphology is examined by scanning electron microscopic examination. Finally, the existence of ion–ion pairs has been identified using Fourier Transform Infrared analysis (FT-IR) measurements.
Book
Electroactive polymers have been the object of increasing academic and industrial interest and in the past ten to fifteen years substantial progress has been achieved in the development and the characterization of this important new class of conducting materials. These materials are usually classified in two large groups, according to the mode of their electric transport. One group includes polymers having transport almost exclusively of the ionic type and they are often called 'polymer electrolytes' or, in a broader way, 'polymer ionics'. The other group includes polymeric materials where the transport mechanism is mainly electronic in nature and which are commonly termed 'conducting polymers'. Ionically conducting polymers or polymer ionics may be typically described as polar macromolecular solids in which one or more of a wide range of salts has been dissolved. The most classic example is the combina­ tion of poly(ethylene oxide), PEO, and lithium salts, LiX. These PEO-LiX polymer ionics were first described and proposed for applications just over ten years ago. The practical relevance of these new materials was im­ mediately recognized and in the course of a few years the field expanded tremendously with the involvement of many academic and industrial lab­ oratories. Following this diversified research activity, the ionic transport mechanism in polymer ionics was soon established and this has led to the development of new host polymers of various types, new salts and advanced polymer architectures which have enabled room temperature conductivity to be raised by several orders of magnitude.
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The properties of the electrode interfaces in polymer electrolytes based on the combination of poly(ethylene oxide) (PEO) and lithium salts, such as LiClO4, have been investigated by impedance spectroscopy. Three main dispersion phenomena characterize the a.c. impedance spectra of the Li/PEO-LiClO4 interface. The evolution of these spectra as a function of time of storage has been explained and interpreted using a solid-polymer layer (SPL) model assuming that the passivation of the lithium surface may be described by a combination of solid inorganic and polymeric layers. The time evolution of the impedance parameters indicates that a passivation film grows rapidly on the lithium surface. The kinetics of the passivation process may be controlled by incorporating into the electrolyte membrane-suitable inhibition agents.
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The discharge/charge characteristics of Li/polymeric solid electrolyte/LiMn2O4 batteries at room temperature were investigated. The battery exhibited a large realizable capacity and long cycle life. The reaction of the interface between lithium electrode and polymeric solid electrolyte is controlled by both the ionic diffusion and the electrochemical reaction, but that of spinel LiMn2O4/polymeric solid electrolyte interface is only limited by the diffusion of lithium cation in the crystal lattice of spinel LiMn2O4, and the diffusion coefficient is 2.1 × 10−12 cm2/s.
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The development of polymer electrolytes which have potential applications in battery technology has resulted in an escalation of research into the synthesis of new macromolecular supports and the mechanisms of ionic transport within the solid matrix. Investigation of the properties of polymer electrolytes has brought together polymer chemists and electrochemists, and the understanding of the solubility and transport of electrolytes in organic polymers is now developing from this pooled experience. This book deals with experimental, theoretical and applied aspects of solid solutions of electrolytes used in coordinating polymer matrices. Attention is focused on the synthesis and properties of these new materials, the mechanisms of conduction processes and practical applications, especially with regard to battery technology.
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Solid polymer electrolytes comprising poly(vinyl acetate) (PVAc), and poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-co-HFP), low molecular weight plasticizer [Ethylene Carbonate (EC)] and different lithium salts (LiBF4, LiClO4, and LiCF3SO3) are prepared by solution casting technique. The electrolyte films are subjected to various characterization techniques such as XRD, FTIR, DSC, SEM and ac impedance analysis. Ionic conductivity is obtained as a function of frequency at various temperatures ranging from 302 to 363 K. The maximum room temperature ionic conductivity is found to be 1.18 × 10−3 S cm−1 for the film containing LiBF4 and the temperature dependent ionic conductivity values seem to obey VTF relation. Microstructure of the samples has been depicted by means of scanning electron microscope. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Article
A novel group of polymer blend electrolytes based on the mixture of poly(vinyl acetate) (PVAc), poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP), and the lithium salt (LiClO4) are prepared by solvent casting technique. Ionic conductivity of the polymer blend electrolytes has been investigated by varying the PVAc and PVdF-HFP content in the polymer matrix. The maximum ionic conductivity has been obtained as 0.527 × 10−4 Scm−1 at 303 K for PVAc/PVdF-HFP ((25/75) wt.%)/LiClO4 (8 wt.%). The complex formations ascertained from XRD and FTIR spectroscopic techniques and the thermal behavior of the prepared samples has been performed by DSC analysis. The surface morphology and the surface roughness are studied using SEM and AFM scanning techniques respectively.
Article
Poly(vinyl acetate), poly(vinylidene fluoride–hexafluoropropylene), lithium perchlorate salt, and the different plasticizer-based gel polymer electrolytes were prepared by solvent-casting technique. The structural and the complex formation have been confirmed by X-ray diffraction spectroscopic analysis. Thermal stability of the different plasticizer-added electrolyte films has been analyzed by means of thermogravimetric analysis. Ionic conductivity of the electrolyte samples has been found as a function of temperature and the plasticizers. Among the various plasticizers, ethylene carbonate-based complexes exhibit maximum ionic conductivity value of the order of 10−4 Scm−1. Finally, the microstructure of the maximum ionic conductivity sample has been depicted with the help of scanning electron microscope analysis.
Article
We studied the system in order to determine the stability of the polymer electrolyte when applied to various electrode pairs. We investigated the thermal stability of the polymer electrolyte in contact with lithium metal and the cathode materials, amorphous , , , and . The properties of the electrolyte were measured by complex impedance analysis and TG‐DTA. It was demonstrated that the electrolyte was stable with lithium metal up to 220°C, and also was stable with the above mentioned cathode materials at temperatures below about 160°C. The decomposition rate of the polymer electrolyte was faster in air than in Ar gas.
Article
Ionic conductivity values for LiSO3CF3 complexes with two amorphous poly(methoxy polyethylene glycol monomethacrylates) (PEM) were determined and values as high as at 373 K and at 293 K were achieved. These values are compared with those obtained for a poly(ethylene oxide) (PEO)-LiSO3CF3 complex of similar salt concentration with an ether oxygen to Li+ ion ratio of 18. The conductivity results for the complexes are similar at temperatures >343 K but at 293 K the values for the conductivities of the PEM-LiSO3CF3 complexes are approximately two orders of magnitude higher than those for the PEO-LiSO3CF3 complex. This difference is believed to be due at least in part to the presence of a large amount of crystalline material in the PEO-LiSO3CF3 complex below 323 K.
Article
We studied the poly(ethylene oxide)-LiCF3SO3 system in order to determine the stability of the polymer electrolyte when applied to various electrode pairs. We investigated the thermal stability of the polymer electrolyte (PEO)8LiCF3SO3 in contact with lithium metal and the cathode materials, amorphous V2O5, LiV3O8, V6O13, and LiCoO2. The properties of the electrolyte were measured by complex impedance analysis and TG-DTA. It was demonstrated that the electrolyte was stable with lithium metal up to 220 C, and also was stable with the above mentioned cathode materials at temperatures below about 160 C. The decomposition rate of the polymer electrolyte was faster in air than in Ar gas.
Article
The Raman and infrared spectra of the systems of plasticizer/LiClOâ and plasticizer/polyacrylonitrile (PAN)/LiClOâ have been recorded, where the plasticizer includes dimethylformamide (DMF) and propylene carbonate (PC). By comparing the spectra, it is found that the association of Li{sup +} ion is more competitive with DMF than with PC in the liquid or gel electrolytes. Moreover, the addition of PAN into DMF/LiClOâ solution has less influence on the Li{sup +}-solvent association than into PC/LiClOâ solution. Although a strong interaction has been observed between Li{sup +} ions and PAN in PC/LiClOâ/PAN electrolytes, no similar interaction is observed between Li{sup +} ion and PAN in DMF/PAN/LiClOâ system. However, after the plasticizer is removed from the gel electrolytes, apparent interaction is observed between Li{sup +} ion and PAN. These phenomena lead to a conclusion that there is a competition between the plasticizer and the polymer for association with the Li{sup +} ions in the PAN-based electrolytes. In addition, it is found that the multiple ion aggregates are formed without the appearance of the usual solvent-shared ion aggregates in the plasticizer-free electrolyte, which suggests that the Li{sup +} ions may move both in the gel state and with the segmental chain of PAN while the ClOâ⁻ anion migrates mainly in the gel state in a practical PAN-based electrolyte.
Article
The changes in thermal and mechanical properties produced by complexation with NaSCN of a poly(ethylene oxide-b-isoprene-b-ethylene oxide) (PEO-PI-PEO) block polymer are described. The number-average molecular weight of the PEO-PI-PEO polymer was 1.67 × 105, and its PEO weight fraction was 0.14. It is shown that complexation, which occurs selectively with the PEO end blocks, can yield a semicrystalline thermoplastic elastomer that melts at about 450 K. The main characteristics of the complexed block polymer are a crystallization temperature, which occurs 90 K lower than that of complexed homo-PEO, and good dimensional stability at high temperature. However, the tensile strength of the complexed material appears to be considerably reduced with increasing temperature. A pronounced supercooling was also observed for the uncomplexed PEO-PI-PEO block polymer. This phenomenon seems to be a general feature of two-phase block polymers in which the crystallizable component is finely dispersed into isolated microdomains.
Article
In order to build solid-state ambient-temperature batteries with stable electrochemical performances over a period of months, the crystallization process in polymer electrolytes can be suppressed by the addition of an elastomer and a styrenic macromonomer of PEO to a PEO-lithium salt electrolyte. Complex impedance measurements and X-ray diffraction studies were carried out in an attempt to understand the effect of the macromonomer on the electrochemical behaviour. The conductivity was found to increase with macromonomer content and values as high as 10−5S cm−1 at room temperature can be obtained. X-ray, diffraction patterns have shown that addition of the elastomer and the macromonomer does not alter the monoclinic unit cell of the crystallized PEO. During ageing, the diffraction lines were found not to vary appreciably over a period of 15 months. Similarly, no appreciable change in the conductivity level was noticed within the same period. The observed behaviour was explained as a suppression of the crystallization process.
Article
Ionic conductivity of poly(vinylchloride) (PVC)/poly(methylmethacrylate) (PMMA) blended electrolytes containing LiCF3SO3 and LiBF4 has been studied using a.c. impedance spectroscopic technique. The variation of conductivity has been investigated as a function of polymer blend ratio, plasticizer content, ethylene carbonate (EC) and propylene carbonate (PC) and lithium salt concentration at 25, 40, 50 and 60°C. Electrolyte films showing conductivities in the 10−3 S cm−1 region have been obtained. A 7:3 PMMA/PVC blend electrolyte at 70% plasticizer content has been found to possess optimal properties in terms of conductivity and mechanical strength.
Article
Electrical conduction in polymers under a relatively low applied electric field is considered to be ionic and is affected strongly by the structural factors of the polymers. The following equation for the electrical conductivity σ was derived in which free volume V<sub>f</sub>, jump energy E<sub>j</sub>, and ionic dissociation energy W were taken into consideration: σ=σ<sub>0</sub> exp - [γ V<sub>i</sub><sup>*</sup>/V<sub>f</sub>+(E<sub>j</sub>+W/2Є)(kT)<sup>-1</sup>] , where σ<sub>o</sub> is a constant, γ the numerical factor to correct the overlap of free volume, V<sub>i</sub><sup>*</sup> the critical volume required for transport of an ion, Є the dielectric constant, k Boltzmann's constant, and T the absolute temperature. This equation describes well the conduction phenomena in polymethylmethacrylate, polystyrene, and an unsaturated polyester. Relationships between electrical conduction and free volume are discussed.
Article
The transport and electrochemical properties of gel-type ionic conducting membranes formed by immobilizing liquid solutions of lithium salts in a poly(methylmethacrylate) matrix have been determined. In particular, the conductivity, the lithium ion transference number and the electrochemical stability window are evaluated and discussed. Finally, particular attention is devoted to the phenomena occuring at the interface between these ionic membranes and the lithium metal electrode.
Article
The electrochemical properties of gel electrolytes formed by the immobilization in a poly(acrylonitrile) matrix of solutions of common lithium salts (eg LiClO4, LiAsF6 and LiN(CF3SO2)2) in organic solvents (eg the propylene carbonate—ethylene carbonate mixture, γ-butyrolactone or the γ-butyrolactone-ethylene carbonate mixture) have been determined. The results indicate that in accordance with previous literature data, these electrolytes have a high ionic conductivity, a wide electrochemical stability window and a high lithium transference number. However, their application in long-life, rechargeable lithium polymer batteries may be hindered by the instability of the negative electrode interface.
Article
Polymer electrolyte membranes comprising poly(vinylidene fluoride), PVDF, Poly(ethylene oxide), PEO, and LiClO4 were prepared and characterised with respect to ambient temperature ionic conductivity (σi). The miscibility studies were performed using XRD and DTA in order to best understand the chemical compatibility between PVDF and PEO. Structural characterisation was carried out on the polymer electrolyte thin film membranes using XRD. The ac-conductivity studies were performed to evaluate the ambient temperature conductivity of the polymer electrolyte membranes. The conductivity and mechanical integrity of PVDF:LiClO4 polymer electrolyte complex were studied as a function of PEO concentration. The addition of PEO into PVDF:LiClO4 complex enhances the room temperature conductivity and mechanical stability of the thin film electrolyte membrane. The maximum conductivity at 30°C was found to be 2.62×10−5 S cm−1 for (PVDF-LiClO4):PEO (80:20) w/o which is two orders of magnitude higher compared to PVDF-LiClO4 system.
Article
Composite polymeric electrolytes form a new group of solid ionic conductors. Several desirable properties make them suitable for application in various electrochemical devices working over a wide temperature range. In this paper some recent developments in the field of composite polymeric electrolytes are described. A comparison between the properties of composite electrolytes containing inorganic and organic fillers is made. This is based on conductivity data obtained from impedance spectroscopy and structural characteristics based on FT-IR, NMR, DSC and EDX methods. A novel concept concerning the mechanism of ionic transport in composite polymeric systems is proposed.
Article
The new plasticised polymer electrolyte comprising the blend of poly-vinyl chloride (PVC) and poly-methylmethacrylate (PMMA) as host polymer is preferable to classical polymer for improving the ionic conductivity in the lithium rechargeable batteries. The nature of plasticizer and lithium salts have been found to influence the ionic conduction of the polymer-blended electrolytes. AC impedance analysis revealed the choice available in imparting ionic conductivity while differential thermogravimetry (DTG) and FTIR analysis have facilitated the effect of molecular interaction on host polymer matrix.
Article
Li+-conductive solid polymer electrolytes with room temperature conductivities of about 2 × 10−3 Ω−1 cm−1 have been developed. Solid-state Li/LiMn2O4 and C/LiNiO2 batteries employing these electrolytes have been fabricated and tested. These batteries have shown room temperature performance reminiscent of their liquid electrolyte counterparts.
Article
The new plasticized polymer electrolyte composed of the blend of poly(vinyl chloride) (PVC) and poly(methyl methacrylate) (PMMA) as a host polymer, the mixture of ethylene carbonate and propylene carbonate as a plasticizer, and LiCF3SO3 as a salt was studied. The effect of the blend ratio and the plasticizer content on the ionic conductions in these electrolytes were investigated. The electrolyte films revealed a phase separated morphology due to immiscibility of the PVC with the plasticizer; the PVC-rich phase and the plasticizer-rich phase were produced during the film casting. The mechanical property was significantly enhanced by the incorporation of PVC into the electrolyte system. The ionic conductivity decreased with increasing the ratio and increased with increasing the plasticizer content. These behaviors were explained in terms of the morphology of the film. Since the plasticizer-rich phase contains much more plasticizer than the PVC-rich phase, the ions preferentially move through plasticizer-rich phase. Due to the slow ionic transport through the PVC-rich phase, the conductivity decreased with increasing ratio.
Applications of electro active polymers. Chap-man & Hall
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