Lithium-conducting Polymer Electrolytes Research Articles

Designing Boron‐Based Single‐Ion Gel Polymer Electrolytes for Lithium Batteries by Photopolymerization

AbstractSingle‐ion lithium conducting polymer electrolytes based on delocalized borate groups are designed and synthesized by rapid UV‐photopolymerization. For this purpose, three different functional lithium boron sp3 anionic monomers, containing fluorinated, ethoxy, or a blend of both functionalities are synthesized. These monomers are photopolymerized in the presence of a poly(ethylene glycol) dimethacrylate crosslinker and tetraglyme as plasticizer. By this method, gel polymer electrolytes endowed with lithium single‐ion conduction are prepared (SIGPEs). The impact generated by the different functionalities of the borate groups and the addition of plasticizer on the electrochemical and ion conducting properties of the synthesized polymer electrolytes are analyzed in detail. These polymer electrolytes show high ionic conductivity (1.71 × 10−4 S cm−1 at 25 °C) and high lithium transference number values (up to 0.85). Finally, they are investigated as solid electrolytes in lithium metal symmetrical cells showing good performance (<0.85 V at ±0.2 mA cm−2 for 175 h).

Single‐Ion Lithium Conducting Polymers with High Ionic Conductivity Based on Borate Pendant Groups

AbstractA family of single‐ion lithium conducting polymer electrolytes based on highly delocalized borate groups is reported. The effect of the nature of the substituents on the boron atom on the ionic conductivity of the resultant methacrylic polymers was analyzed. To the best of our knowledge the lithium borate polymers endowed with flexible and electron‐withdrawing substituents presents the highest ionic conductivity reported for a lithium single‐ion conducting homopolymer (1.65×10−4 S cm−1 at 60 °C). This together with its high lithium transference number t =0.93 and electrochemical stability window of 4.2 V vs Li0/Li+ show promise for application in lithium batteries. To illustrate this, a lithium borate monomer was integrated into a single‐ion gel polymer electrolyte which showed good performance on lithium symmetrical cells (<0.85 V at ±0.2 mA cm−2 for 175 h).

Single-Ion Lithium Conducting Polymers with High Ionic Conductivity Based on Borate Pendant Groups.

A family of single‐ion lithium conducting polymer electrolytes based on highly delocalized borate groups is reported. The effect of the nature of the substituents on the boron atom on the ionic conductivity of the resultant methacrylic polymers was analyzed. To the best of our knowledge the lithium borate polymers endowed with flexible and electron‐withdrawing substituents presents the highest ionic conductivity reported for a lithium single‐ion conducting homopolymer (1.65×10−4 S cm−1 at 60 °C). This together with its high lithium transference number t Li+ =0.93 and electrochemical stability window of 4.2 V vs Li0/Li+ show promise for application in lithium batteries. To illustrate this, a lithium borate monomer was integrated into a single‐ion gel polymer electrolyte which showed good performance on lithium symmetrical cells (<0.85 V at ±0.2 mA cm−2 for 175 h).

Study of the structure and electrical conductivity of lithium-conducting polymer electrolytes based on PEG-1500—LiX (X = SCN, N(CF3SO2)2)

A comprehensive study of lithium-conducting polymer electrolytes based on polyethylene glycol 1500 and lithium salts (LiSCN and LiN(CF3SO2)2) was carried out using thermogravimetry, differential thermal analysis, electrometry, and vibrational spectroscopy. Their phase composition was refined, structural changes resulting from varying the concentration of lithium salts were determined, the most probable structures of complex solvate and ionic complexes were established.

Ion aggregation and phase separation in amorphous poly(nitrile)-based lithium conducting polymer electrolytes

In this paper, we analyse ion association, the formation of high ionic aggregates and phase separation in amorphous solvent-free polymer electrolytes based on a butadiene and acrylonitrile (PBAN) copolymer and lithium salts having different anion geometries – LiClO4, LiAsF6 and LiBr. The analysis is carried out on the basis of the results of quantum chemical calculations at the RTF + MP2/6-311G** level of theory using the GAMESS (US) and Firefly software packages. It is established that the solubility of the salts under study in PBAN is strongly correlated with the dimensionality of the most stable high ionic aggregates {Li+X−}m (where X− = Br−, ClO4−, AsF6− and m = 1–6): the formation of 3D species causes salt precipitation, while the 1D and 2D species determine the high solubility of the salts. On the basis of thermodynamic considerations, we conclude that ion clustering in PBAN-based electrolytes can be attributed to the existence of metastable supersaturated solutions near the limit of salt solubility. These ion clusters can be considered as fluctuations in salt concentration stabilised through the coordination of nitrile groups being part of polynitriles.

Controlling domain orientation of liquid crystalline block copolymer in thin films through tuning mesogenic chemical structures

ABSTRACTControlling the macroscopic orientation of nanoscale periodic structures of amphiphilic liquid crystalline block copolymers (LC BCPs) is important to a variety of technical applications (e.g., lithium conducting polymer electrolytes). To study LC BCP domain orientation, a series of LC BCPs containing a poly(ethylene oxide) (PEO) block as a conventional hydrophilic coil block and LC blocks containing azobenzene mesogens is designed and synthesized. LC ordering in thin films of the BCP leads to the formation of highly ordered, microphase‐separated nanostructures, with hexagonally arranged PEO cylinders. Substitution on the tail of the azobenzene mesogen is shown to control the orientation of the PEO cylinders. When the substitution on the mesogenic tails is an alkyl chain, the PEO cylinders have a perpendicular orientation to the substrate surface, provided the thin film is above a critical thickness value. In contrast, when the substitution on the mesogenic tails has an ether group the PEO cylinders assemble parallel to the substrate surface regardless of the film thickness value. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017, 55, 532–541

Composite gel-type polymer electrolytes for advanced, rechargeable lithium batteries

The main goal of this work was to determine whether the dispersion of ceramic fillers have any promotion effect on the properties of solid-like, gel-type lithium conducting polymer electrolytes. Using a series of different but complementary techniques, which included SEM analysis, voltammetry and impedance spectroscopy, we demonstrate that the dispersion of surface functionalized fumed silica and alumina, respectively, to PVdF–carbonate solvent–lithium salt systems, while not greatly influencing the transport properties, does stabilize the lithium metal interface and the mechanical properties of the resulting composite GPE electrolytes. The relevance of these features in view of practical application is here demonstrated by the response of lithium batteries based on selected GPEs.

Advanced, lithium batteries based on high-performance composite polymer electrolytes

Progress in lithium battery technology may be achieved by passing from a conventional liquid electrolyte structure to a solid-state, polymer configuration. In this prospect, great R&D effort has been devoted to the development of suitable lithium conducting polymer electrolytes. In previous papers [F. Croce, L. Settimi, B. Scrosati, Electrochem. Commun. 8 (2006) 364 [1]; F. Croce, S. Sacchetti, B. Scrosati, J. Power Sources, in press [2]], we have shown that composite membranes based on blends between poly(ethylene oxide) and lithium salts with the dispersion of functionalized ZrO 2 ceramic filler, have unique transport and interfacial properties. In this paper, we complete the study of these advanced polymer electrolytes by evaluating their use in rechargeable lithium batteries. The results confirm the practical interest of these electrolytes which appear to be suitable for the fabrication of batteries directed to application in emerging technologies, such as those associated to hybrid and electric vehicles.

Advanced, high-performance composite polymer electrolytes for lithium batteries

Progress in lithium battery technology may be achieved by passing from a conventional liquid electrolyte structure to a solid-state, polymer configuration. In this prospect, great R&D effort has been devoted to the development of suitable lithium conducting polymer electrolytes. The most promising results have been obtained with systems based on blends between poly(ethylene oxide) and lithium salts. In this work we show that the transport and interfacial properties of these electrolytes may be greatly enhanced by the dispersion of a ceramic filler having an unique surface state condition. The results, in addition to their practical reflection in the lithium polymer electrolyte battery technology, also provide a valid support to the model which ascribes the enhancement of the transport properties of ceramic-added composites to the specific Lewis acid–base interactions between the ceramic surface states and both the lithium salt anion and the PEO-chains .

High performance nanocomposite polymer electrolytes

Solid lithium-conducting nanocomposite polymer electrolytes based on poly(oxyethylene) (POE) were prepared using high aspect ratio cellulosic whiskers and lithium imide salt, LiTFSI. The cellulosic whiskers were extracted from tunicate — a sea animal — and consisted of slender parallelepiped rods that have an average length around 1 μm and a width close to 15 nm. High performance nanocomposite electrolytes were obtained. The filler provided a high reinforcing effect, despite the favorable cellulose/POE interactions that were expected to decrease the possibility of inter-whisker connection and formation of a percolating cellulosic network, while a high level of ionic conductivity was retained with respect to unfilled polymer electrolytes. Cross-linking and plasticizing of the matrix as well as preparation of the composites from an organic medium were also investigated.

Lithium-Conducting Polymer Electrolytes for Chemical Power Sources

Lithium-Conducting Polymer Electrolytes for Chemical Power Sources

PEO-Based Electrolyte Membranes Based on LiBC4 O 8 Salt

New types of solvent-free, lithium-conducting polymer electrolytes have been prepared by hot-pressing a blend of poly(ethylene oxide) (PEO) and a lithium bis(oxalato)borate, (LiBOB) salt. The membranes have been characterized in terms of ionic conductivity and lithium ion transference number. In addition, the thermal and the structural properties were investigated by differential scanning calorimetry and X-ray diffraction. The results show that the PEO-LiBOB membranes have a high ionic conductivity even at low-medium temperatures. © 2004 The Electrochemical Society. All rights reserved.

Effect of Additions of Organic Sulfonates on the Conductivity of Lithium Conducting Polymer Electrolytes

Effect of Additions of Organic Sulfonates on the Conductivity of Lithium Conducting Polymer Electrolytes

Physical and Chemical Properties of Nanocomposite Polymer Electrolytes

The physical and chemical properties of a new class of lithium conducting polymer electrolytes formed by dispersing ceramic powders at the nanoscale particle size into a poly(ethylenoxide) (PEO)− lithium salt, LiX complexes, are reported and discussed. These true solid-state PEO−LiX nanocomposite polymer electrolytes have in the 30−80 °C range an excellent mechanical stability (due to the network of the ceramic fillers into the polymer bulk) and high ionic conductivity (promoted by the high surface area of the dispersed fillers). These important and unique properties are accompanied by a wide electrochemical stability and by a good compatibility with the lithium electrode (assured by the absence of any liquids and by the interfacial stabilizing action of the dispersed filler), all this making these nanocomposite electrolytes of definite interest for the development of advanced rechargeable lithium batteries.