Lithium Ion Conducting Polymer Electrolytes Research Articles

Lithiated Nafion membrane as a single-ion conducting polymer electrolyte in lithium batteries

AbstractSingle lithium-ion conducting polymer electrolytes are promising candidates for next generation safer lithium batteries. In this work, Li+-conducting Nafion membranes have been synthesized by using a novel single-step procedure. The Li-Nafion membranes were characterized by means of small-wide angle X-ray scattering, infrared spectroscopy and thermal analysis, for validating the proposed lithiation method. The obtained membranes were swollen in different organic aprotic solvent mixtures and characterized in terms of ionic conductivity, electrochemical stability window, lithium stripping-deposition ability and their interface properties versus lithium metal. The membrane swollen in ethylene carbonate:propylene carbonate (EC:PC, 1:1 w/w) displays good temperature-activated ionic conductivities (σ ≈ 5.5 × 10–4 S cm−1 at 60 °C) and a more stable Li-electrolyte interface with respect to the other samples. This Li-Nafion membrane was tested in a lithium-metal cell adopting LiFePO4 as cathode material. A specific capacity of 140 mAhg−1, after 50 cycles, was achieved at 30 °C, demonstrating the feasibility of the proposed Li-Nafion membrane.

Opportunity for lithium-ion conducting polymer electrolytes beyond polyethers

Lithium-ion conducting solid polymer electrolytes (SPEs) are of particular interest for battery applications. In addition to their relatively easy scalability to industrial scale, the ductility and processability of SPEs allows intimate contact between electrode and electrolyte materials, which ensures low cell resistance and thus better cycling performance. Herein, we focus on the non-polyether-based polymers developed for building lithium-ion conducting SPEs, with the aim of circumventing the dilemmas encountered by classic polyether-based SPEs. This review highlights the recent progresses and advances in the development of several kinds of interesting polymer host matrices, including carbonyl-containing polymers [e.g., polycarbonates, polyesters], ionomers-based polymers [e.g., poly(ionic liquids)], fluorine-based polymers, nitrile-based polymers, and so on. Particular attention is paid to the differences between alternative polymer chemistries and polyether systems, in terms of ion transport behavior [e.g., ionic conductivity, cationic transport number], electrochemical properties [e.g., anodic and cathodic stability], compatibility with electrode materials, etc. Possible solutions to further enhance the performances of non-polyether-type SPEs are also discussed.

The role of nanoceramic additives surface charge on the ionic transport of single lithium-ion conducting polymer electrolytes

The role of nanoceramic additives surface charge on the ionic transport of single lithium-ion conducting polymer electrolytes

Chain length dependence of structural and transport properties of single lithium-ion conducting polymer electrolytes: A molecular dynamics simulation study

In this work, the parameters affecting the performance of polymer electrolytes, for utilization in lithium-ion batteries (LiBs) are investigated. For this purpose, by using density functional theory (DFT) and molecular dynamics (MD) simulation, the structural and transport properties of single lithium-ion conducting polymer electrolytes (SLICPEs) based on boron ethylene glycol (BEG), as the anion, with the molecular structure ofBO3−−C2H4On−BO4− are evaluated. The calculated structural properties, include density, glass transition temperature, and radial distribution function (RDF). The simulated transport properties are diffusion coefficient, transference number, and ionic conductivity. In the first step, the optimization of molecular structures is obtained by DFT calculations with B3LYP functional approximation and Mullikan partial charges for the polymer chain lengths of 1, 4, 8, and 15 monomers. Then, by using MD simulations and an ten-stages compression-expansion procedure, the studied electrolyte systems are equilibrated. The results indicate that the transference numbers of these electrolytes are significantly higher than those of commonly used electrolytes based on polyethylene oxide (PEO). Inspection of the obtained results indicates that the diffusion and ionic conductivity coefficients are influenced by the interaction of Li+ with oxygen atoms in the polymer chain. Analysis of the transport properties of Li+ along the polymer chain structure reveals that the presence of a boron atom in the polymer chain backbone induces a significant non–uniform charge distribution along the polymer chain and as a result weakens the interaction between Li+ with an oxygen atom in the polymer chain. Therefore compared to the conventional electrolytes, Li+ can move more freely along the polymer chain, and as a result, the performance of LiBs is promoted significantly.

Nanoscale Ionic Materials for Nafion Based Nanocomposites Membranes As Single Lithium-Ion Conducting Polymer Electrolytes for Lithium Sulfur Batteries

Currently, rechargeable batteries with the lithium–sulfur (Li–S) chemistry has attracted great interest as one of the most promising candidates for next generation electrochemical energy storage systems. Research into these high energy density devices is critical to the development of thinner, lighter, and lower cost battery systems. One of the biggest obstacles for practical applications of Li-S batteries is caused by the soluble nature of the highly ordered lithium polysulfides (Li2Sn) in the organic electrolytes and induce a so-called “shuttle effect”. A solid-state electrolyte (SPEs) could be a valid alternative in terms of reducing the polysulfides dissolution and shuttle, as well as to protect the lithium metal anode and to minimize dendrite formation, which is beneficial for improving the safety and cycle life of Li−S batteries. SPEs are typically dual-ion conductor systems both cations and anions are mobile and cause a concentration polarization leading to poor performances of batteries. Recently, single lithium-ion conducting solid polymer electrolytes (SLIC-SPEs) have been proposed for polymer electrolytes, where anions are covalently bonded to the polymer, inorganic backbone, or immobilized by anion acceptors and only the Li+ cation will contribute to a permanent flow of charge. They have advantages over conventional dual-ion conducting SPEs such as unity transference number, absence of harmful effect of anion polarization, extremely low rate of Li dendrite growth and immobilization of the lithium polysulfides in the lithium-sulfur (Li-S) batteries. Polymer electrolytes based on ionomers (e.g., Nafion) with easily ionizable groups (e.g., sulfonic groups covalently bonded to the polymer side-chains, −CF2SO3 −) are promising thanks to the high concentration of weakly coordinating anions (counterions). In this work, lithiated Nafion and Nafion-nanocomposites membranes based on Nanoscale Ionic Materials (NIMs) were synthesized, and their ionic conductivity and lithium transference number were investigated in common nonaqueous organic solvents (EC/PC and Glymes).A thorough and systematic study of the lithium-ion transport was conducted by p 1H and 7Li pulsed field gradient (PFG) NMR spectroscopy and electrochemical impedance spectroscopy (EIS), while the mechanical properties of the film electrolytes have been tested by dynamic mechanical analysis (DMA) in a wide temperature range. The electrochemical studies have been conducted both in Li/Li symmetric cell and in secondary Li-S cells. The preliminary results are very interesting, showing ionic conductivities of the order of 5 × 10-4 S/ cm at 25°C satisfactory properties in terms of stability window and stability of the lithium stripping. The lithium transport number is very close to unity thus confirming the complete immobilization of the negative charge carriers.

Hybrid gel polymer electrolyte based on 1-methyl-1-Propylpyrrolidinium Bis(Trifluoromethanesulfonyl) imide for flexible and shape-variant lithium secondary batteries

Lithium ion conducting polymer electrolytes with broad electrochemical stability, good mechanical strength, high thermal stability, and easy processability are necessary for all-solid-state and shape-variant lithium secondary batteries. Hybrid gel polymer electrolytes incorporating an ionic liquid have been attracting attention for application in solid-state lithium secondary batteries owing to their superior thermal properties compared to conventional electrolyte systems. In this study, a variety of polymer electrolytes based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP), lithium bis(trifluoromethanesulfonyl) imide (LiTFSI), and 1-methyl-1-propylpyrrolidinium bis(trifluoromethanesulfonyl) imide (PMPyrrTFSI) are prepared, and an in-depth study of their composition dependence and electrical properties is conducted to develop the optimum composition. The composition dependent ionic conductivity of the polymer electrolyte increases with increasing LiTFSI and PMPyrrTFSI and reaches a maximum value of 6.93 × 10−4 S cm−1 at room temperature (25 °C) when the polymer electrolyte contains 30 wt% LiTFSI and 60 wt% PMPyrrTFSI. In addition, the optimized gel polymer electrolytes consisting of PVdF-HFP/LiTFSI/PMPyrrTFSI (70/30/60 by weight, i.e., 70PVdF-HFP/30LiTFSI/60PMPyrrTFSI) look transparent and exhibit high mechanical stability and excellent thermal stability up to 420 °C. Finally, the lithium iron phosphate (LiFePO4)/lithium metal solid-state cells coupled with the optimized gel polymer electrolyte are prepared, and their discharge characteristics are studied. The 70PVdF-HFP/30LiTFSI/60PMPyrrTFSI based solid-state cell delivered a maximum discharge capacity of 151 mAh g−1 at room temperature with a good rate capability and cycling performance.

Fire-retardant sp3 boron-based single ion conducting polymer electrolyte for safe, high efficiency and dendrite-free Li-metal batteries

Single lithium ion conducting polymer electrolytes (SIPEs) are an emerging class of alternative polymer electrolytes for protecting lithium metal anode. This work explores a fully aromatic sp3 boron based SIPE, lithium poly (4,4′-dihydroxydiphenyl sulfone borate), Li-PSB, via a one-step synthetic procedure. A series of highly porous SIPE membranes, defined as po-PBSBs, comprising of Li-PSB and a fully aromatic polybenzimidazole (PBI) binder are firstly prepared. As a polymer electrolyte, po-PBSB exhibits high lithium ion transference number of close to unity, high ionic conductivity, excellent thermal dimensional stability and promising flame-retardant. X-ray Photoelectron Spectroscopy (XPS) and Density Functional Theory (DFT) calculations depict multi-coordinated lithium ion transport channels in the po-PBSB membranes. By serving as polymer electrolyte in lithium metal batteries (LMBs), Li/LiFePO4 (LFP) cell, the po-PBSB shows an effective suppression of lithium dendrite growth. As a consequence, po-PBSB based Li/LFP cell demonstrates superior cycling performance remaining 76.1% of its initial capacity with nearly 100% coulombic efficiency at 1.0C after 200 cycles. The excellent performance may be ascribed to the remarkable lithium ion transference number, high organic solvent absorption in pores and thermal and electrochemical stabilities of the po-PBSB. We believe that the novel SIPE materials have great potential for application in high-safety LMBs.

The D.C electrical properties of Lithium ion conducting solid polymer electrolyte based on polyvinyl alcohol

Lithium ion conducting polymer electrolyte films based on polyvinyl alcohol (PVA) with different concentration of lithium perchlorate salt, using a solution cast technique, have been prepared. The Solid polymer electrolyte (SPE) hasbeen characterized by XRD technique. The XRD analysis reveals the amorphous nature of the polymer electrolyte. Polymer sample of PVA with different concentration of lithium salt (0, 5, 10, 20) wt% with double distilled water as solvent have been prepared and studied. High conductivity of 1.85771X10-07 has been observed for the PVA with 20% LiClO4. The temperature dependent conductivity of polymer electrolyte follows the Arrhenius relationship which shows hopping of ion in the polymer system. The experiment result showed that the D.C electrical conductivity increased with increasing the lithium salt concentration.

High Conductivity, Lithium Ion Conducting Polymer Electrolyte Based on Hydrocarbon Backbone with Pendent Carbonate

Solid polymer electrolytes (sPE) offer a pathway for safer, less flammable lithium batteries. However, developing a polymer that provides high Li+ mobility as well electrochemical stability remains a challenge, because ion conductive functional units in the polymer main-chain (e.g., polycarbonate and polyether) usually suffer from poor electrochemical stability at high and low potentials. Herein, an sPE with pendent carbonate on a hydrocarbon backbone has been designed and synthesized to overcome conductivity and electrochemical stability problems. This pendant polycarbonate is different from conventional polycarbonate electrolytes because the carbonate moiety is in the sidechain, which mitigates polycarbonate backbone stability problems while still providing high ionic conductivity when used with a plasticizer. Conductivity as high as 1.1 mS cm−1 at 22 °C was obtained. Stable lithium metal plating and stripping using the sPE was observed for 1,200 h and electrochemical stability up to 4.6 V vs Li+/Li has been demonstrated. The low interfacial resistance (<160 ohm∙cm2 at 22 °C) and reasonable ionic conductivity have enabled acceptable cycling performance in a Li-LiFePO4 battery at 0.98 mA cm−2 for 2,300 cycles.

A Novel Li+-Nafion-Sulfonated Graphene Oxide Membrane as Single Lithium-Ion Conducting Polymer Electrolyte for Lithium Batteries

Single lithium-ion conducting polymer electrolytes are an innovative concept of solid-state polymer electrolytes (SPEs) for lithium-battery technology. In this work, a lithiated Nafion nanocomposit...

Charge Delocalization on BO4– Centers to Improve Conductivity on Single Lithium Ion Conducting Polymer Electrolytes: A Computational/Experimental Approach

Single lithium ion conducting polymer electrolytes (SLICPEs) could be one of the best options for safer lithium ion batteries, only if new strategies can be envisaged to improve their ionic conduct...

Semi-Interpenetrating Networks for All-Solid-State Lithium Metal Batteries

In the past two decades, exponentially growing markets of mobile consumer electronics and electric vehicles caused an increasing demand towards higher energy and power density in energy storage technologies. Aiming to overcome the intrinsic limitations of state of the art liquid organic carbonate-based electrolytes with regard to higher energy densities and cost efficient cells solid state electrolytes are a promising topic of research. Enabling not only the use of electrolyte layers in the range of a few micrometers and a reduction of needed security features of the cell housing, but also the utilization of lithium metal as anode. Besides the prominent classes of oxidic ceramic and sulfidic glassy electrolytes, the class of lithium ion conducting polymer electrolytes comprises a large variety of different subclasses. The subclass of semi-interpenetrating networks (s-IPNs) defines a combination of at least two polymer networks penetrating each other without a covalent bonding between the different polymer species. Thanks to its excellent interface wetting ability, processability and lithium metal compatibility, polyethylene oxide (PEO) was selected as lithium ion conducting polymer.[1] This combination of different polymer types allows the tailoring of vital physicochemical and electrochemical properties of the resulting s-IPN membranes. Possible benefits of a second interwoven polymer matrix refer to the reduction/suppression of PEO crystallization inside of confinements, thus allowing the utilization of polymer membranes at ambient temperature, an enhanced mechanical stability of thin film membranes compared to single polymer materials and the improved homogeneity of lithium precipitation by a more defined interface structure.[2] Depending on the preparation route of the s-IPN, not only the polymer itself but also the polymer interfaces can be tuned selectively by introduction of, for example, highly hydrophobic substances like siloxanes, which tend to accumulate at the membrane surfaces.[3] The prepared s-IPN membranes in this work were investigated by means of selected thermal, electrochemical and spectroscopy techniques including differential scanning calorimetry, galvanostatic and potentiostatic experiments as well as impedance spectroscopy. This work aims for an economic approach to tailor vital physicochemical properties of s-IPN electrolyte membranes by utilization of PEO as lithium ion conductor and lithium metal as anode material using a single-step solution casting synthesis route towards advanced all-solid-state lithium metal batteries.

Synthesis of Single Lithium-Ion Conducting Polymer Electrolyte Membrane for Solid-State Lithium Metal Batteries

Synthesis of single lithium-ion conducting polymer electrolyte membrane (SLIC-PEM) composed of polymerized lithium 4-styrenesulfonyl(trifluoromethylsulfonyl)imide (PLiSTFSI), poly(ethylene glycol) methyl ether methacrylate (PEGM), poly(ethylene glycol) dimethacrylate (PEGDMA), and ethylene carbonate (EC) is reported. SLIC-PEM combines the advantages of single lithium-ion conducting polymer electrolytes, cross-linked flexible polymer electrolytes, and the liquid electrolyte of carbonate. The synthesized SLIC-PEMs have superior thermostability, high ionic conductivity, a wide electrochemical window, and high lithium-ion transference number. The corresponding LiFePO4|SLIC-PEM|Li cell delivers high Coulombic efficiency and excellent discharge capacity and cycling performance, demonstrating that SLIC-PEMs will have promising application in next-generation safe lithium metal batteries.

New single lithium ion conducting polymer electrolyte derived from delocalized tetrazolate bonding to polyurethane

In this work, a new class of single Li-ion conducting polyelectrolytes (SLICPs) were skillfully synthesized from highly delocalized lithium tetrazolate, polyethylene glycols (PEGs) and diisocyanates. The chemical composition of SLICPs was confirmed by FT-IR, NMR and XPS, and the physical and electrochemical properties were investigated with XRD, SEM, DSC, TG, EIS, LSV, etc. The results showed that the related properties could be tailored using various diisocyanates and PEGs, and the SLICPs comprising PEG1000 exhibited higher ionic conductivities and Li+ transference number. It was noted that the conductivity of SLICP prepared from isophorone diisocyanate, lithium tetrazolate and PEG 1000 (IPULi-1000) could be close to 1 × 10−4 S cm−1 at 80 °C without uptake of any organic solvents. Besides, the polymer electrolytes could endure an oxidation potential up to 4.2 V (vs. Li+/Li), and the stable cycle (more than 200 cycles for Li/Li symmetric cell at 30 °C) indicated that the developed SLICPs were compatible with lithium electrode. Hence, the developed SLICPs were promising solid polymer electrolytes materials for Lithium batteries.

Electrochemical Characterization of Single Lithium-Ion Conducting Polymer Electrolytes Based on sp3 Boron and Poly(ethylene glycol) Bridges

A novel series of single lithium-ion conducting polymer electrolytes (SLICPE) based on sp3 boron and poly(ethylene glycol) (PEG) bridges is presented, in the context of the development of a new generation of batteries, with the aim to overcome the problems related to concentration overpotential and low ion transport numbers in conventional solid polymer electrolytes (SPE). The phase separation generated by the physical mixture of SPE with plasticizers such as poly(ethylene oxide) is still a serious problem. In this work, the use of PEG with different chain lengths, for the polycondensation reaction with LiB(OCH3)4, to synthesize SLICPE allows preventing phase separation while tuning the predominant conduction mechanism, and thus the electrical properties, especially the lithium-ion transference number. The ionic transport is promoted by chain mobility as the chain length is increased. SLICPE with the best ionic conductivity values (4.95 ± 0.05) × 10-6 S cm-1 was the one synthesized from poly(ethylene glycol) with an average MN of 400 (BEG8), having an O/Li+ ratio of 20. The lithium transference number ( tLi+) and electrochemical stability window of SLICPE membranes at 25 °C decreased as the PEG bridge length between sp3 boron atoms increased from 0.97 to 0.88 and 5.4 to 4.2 V vs Li0/Li+, respectively, for SLICPE synthesized from PEG with an average MN of 50-400 (BEG1 to BEG8).

Investigation on the Electrical Properties of Lithium Ion Conducting Polymer Electrolyte Films Based on Biodegradable Polymer Blends

In the present work, the polyvinyl alcohol/poly (N-vinyl pyrrolidone)/Lithium carbonate (PVA/PVP/Li2CO3) blend polymer electrolyte films were prepared via the solution casting technique, with varying concentration of Li2CO3 salt (0 to 25 wt%). The surface morphology of these blend electrolyte films was examined using polarized optical microscopy (POM). The electrical properties such as impedance (Z), quality factor (Q-factor) and phase angle () of PVA/PVP/Li2CO3 blend electrolyte films were elucidated using impedance analyzer in the frequencies from 50 Hz to 20 MHz and temperatures from 30 °C to 150 °C. It was observed that the inclusion of Li2CO3 salt into the PVA/PVP blend matrix led to an increase in the Z,  and Q-factor values. The maximum Z of 1.19 x 107 Ω (50 Hz, 30 °C) was observed for blend electrolyte film containing 25 wt% Li2CO3 salt. The  also increased from 139° (20 MHz, 90 °C) for PVA/PVP blend to 179° (20 MHz, 40 °C) for blend electrolyte film containing 25 wt% Li2CO3 salt. The Q-factor values was increased from 27.4 (10 MHz, 140 °C) for PVA/PVP blend to 56.2 (5 MHz,salt, 80 °C) for blend electrolyte film containing 25 wt% Li2CO3 salt.

Asymmetrical Sp 3 Boron Atoms with Poly(Ethylene Glycol) Bridges As Single Lithium Ion Conducting Polymer Electrolytes

Single lithium ion conducting polymers electrolytes (SLICPE) are characterized by a high lithium ion transference number and low concentration polarization [1]. However, the ionic conductivity values need to be increased in order to obtain better performance in batteries. In general, two different approaches are used to increase the ionic conductivity in SLICPE, the first consists of a simple process of mixing lithium polymer salts with flexible polymers such as Poly(ethylene oxide) (PEO) . However, in this type of SLICPE phase separation between the polymer matrix and the lithium polymer salt can be generated, causing loss of contact between the electrode and the electrolyte, as well as conductivity decrease. The second form of elaboration of SLICPE consists of the synthesis of copolymers containing units with a relatively large segmental movement, which have anions covalently bonded to the polymer. However, the synthesis of this type of SLICPE is generally complicated and expensive [2]. In this work, we report the electrochemical characterization of a series of SLICPE based on sp3 boron atoms, homogeneously distributed in a way by means of poly(ethylene glycol) PEG bridges of different lengths that allow easily modulating the physical, electrochemical and ionic conduction properties. SLICPE were synthesized by a conventional fusion method, and samples were characterized by NMR, and electrochemical impedance spectroscopy (EIS) in symmetrical cells in the range between 20 and 90°C. In addition, the effect of charge delocalization present in BO4 - groups, associated to strong electron-withdrawing substituents and their effect on the ionic conductivity in SLICPE, was studied. Results indicate a decrease on the activation energy for Li+ transport as function of the ethoxy chains length from 0.053 to 0.023 eV for the PEG chain of one and eight ethoxy groups, respectively. These results suggest that in short ethoxy chains the ion conduction mechanism is predominantly owed to hopping between boron centers (B-EO-B) while in larger chains it evolves to a hopping mechanism between boron atoms and ethoxy groups (B-(EO)n-B). In general, the analysis of the results indicates that the ionic conductivity (10-4 Scm-1 @ 60°C). However, these values can increase in a function of the degree of delocalization of negative charge on the receptor anion and make this class of polymer electrolytes promising candidates for LIB specially at elevated temperatures [3]. Acknowledgements This work was supported by Fondo de Sustentabilidad project 245754 “Predicción, síntesis, elaboración y calibración de celdas fotovoltaicas y baterías de flujo. ER thanks CONACYT (project 253155), GR thanks (project seciti/080/2017) IG thanks CONACYT (proyect 237343) for financial support. G. Guzman is grateful to CONACYT for the scholarship granted to pursue his doctoral studies. Reference s : [1] V. Di Noto, S. Lavina, G.A. Giffin, E. Negro, B. Scrosati, Electrochimica Acta, 57 (2011) 4-13. [2] H. Zhang, C. Li, M. Piszcz, E. Coya, T. Rojo, L.M. Rodriguez-Martinez, M. Armand, Z. Zhou, Chemical Society Reviews, 46 (2017) 797-815. [3] G. Guzmán-González, H. J. Ávila-Paredes1, E. Rivera, I González. ACS Applied Materials & Interfaces - under reviews.

Pre-irradiation grafted single lithium-ion conducting polymer electrolyte based on poly(vinylidene fluoride)

In this work, a poly(vinylidene fluoride) (PVDF)-based copolymer is synthesized by grafting two kinds of monomer, 2, 2, 3, 4, 4,-hexafluorobutyl methacrylate (HFMA) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS), onto the PVDF powder with pre-irradiation grafting copolymerization. Then a new single lithium-ion conducting polymer electrolyte (SIPE) is prepared by solution casting of the radiation grafted PVDF-based copolymer powder with subsequent lithiation process. Its chemical structure, crystal form, and membrane morphology are characterized by nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM), etc. The mechanical properties exhibit the elongation at break of 72% and the tensile strength of 28 MPa. Comparatively high values of ionic conductivity, up to 2.08 × 10−5 S cm−1 at 30 °C, are obtained, combined with lithium-ion transference number of 0.93 and stable electrochemically oxidation voltage as high as 4.4 V vs Li/Li+. Except for these promising features, the SIPE cell with lithium ion conduction network has a stable charge/discharge cycling performance with various C-rates at room temperature. As-prepared SIPE shows a great prospect for the application in lithium-ion batteries.

A star-shaped single lithium-ion conducting copolymer by grafting a POSS nanoparticle

Single-ion conducting polymer electrolytes (SCPE) are attractive candidates for high-performance energy storage devices. A star-shaped single lithium-ion conducting polymer electrolyte was synthesized by combining the “grafting to” and “grafting from” strategy utilizing a polyhedral oligomeric silsesquioxane (POSS) nanoparticle as the core. Carboxylic acid terminated polyethylene oxide (PEO) and Reversible Addition Fragmentation Chain Transfer Agent (RAFT-CTA) were attached to the POSS nanoparticle to form a POSS-cored macro RAFT CTA (PMR-CTA). The PMR-CTA was used to mediate the polymerization of potassium (styrene-4-sulfonyltrifluoromethyl-sulfonyl)imide (STF-K+) and subsequent counter ion exchange resulted in a star-shaped single lithium-ion conducting copolymer (SSCP-Li+). The grafting ratio of poly(STF-Li+) and PEO per POSS nanoparticle can be tuned by modifying the feed ratio of the two polymer components. The synthesized star-shaped SCPE-Li+ are characterized by 1H NMR, FT-IR, UV-Vis, DLS, GPC and DSC, and their ionic conductivity is studied by broadband dielectric spectroscopy. The obtained results are compared to a conventional linear homopolymer poly(STF-Li+) and block copolymer PEO-b-poly(STF-Li+), and reveal a significant “decoupling” of ion conductivity from segmental dynamics for all of the studied SCPE-Li+. Blending extra PEOs with SCPE-Li+ was also performed to improve the ionic conductivity.

Lithium ion-conducting polymer electrolytes based on PVA–PAN doped with lithium triflate

Blend polymer electrolytes with optimized composition (92.5 PVA:7.5 PAN) doped with lithium triflate (LiCF3SO3) have been prepared in different concentrations by solution casting technique, using DMF as solvent. The prepared electrolytes have been characterized by XRD, FTIR, DSC, AC impedance, and SEM techniques. The complex formation between the blend polymer and the salt has been confirmed by X-ray diffraction and FTIR analyses. Differential scanning calorimetry thermogram has shown a decrease in glass transition temperature with the addition of salt. It has been observed that the ionic conductivity of the doped blend polymer electrolyte increases as the salt concentration increases. The ionic conductivity has been found to be 4.0 × 10−5 S cm−1 for 92.5 PVA:7.5 PAN:50 M wt% LiCF3SO3 sample at room temperature. The temperature dependence of ionic conductivity has been studied with Arrhenius plot and the activation energies have been calculated. Primary lithium ion battery has been constructed with the configuration Zn + ZnSO4 7H2O/ 92.5 PVA:7.5 PAN:50 M wt% LiCF3SO3/ PbO2 + V2O5 using the maximum conducting blend polymer, and its discharge characteristics have been studied.