Synthesis and characterization of SrBi4Ti4O15 ferroelectric filler based composite polymer electrolytes for lithium ion batteries

Composite polymer electrolytes (CPEs) based on poly (ethylene oxide) (PEO) (Mol.Wt similar to 6 x 10(5)) complexed with LiN(CF3SO2)(2) lithium salt and SrBi4Ti4O15 ferroelectric ceramic filler have been prepared as films. Citrate gel technique and conventional solid state technique were employed for the synthesis of the ferroelectric fillers in order to study the effect of particle size of the filler on ionic conductivity of the polymer electrolyte. Characterization techniques such as X-ray diffraction (XRD), differential thermal analysis (DTA), scanning electron microscopy (SEM) and temperature dependant DC conductivity studies were taken for the prepared polymer composite electrolytes. The broadening of DTA endotherms on addition of ceramic fillers to the polymer salt complex indicated the reduction in crystallinity. An enhancement in conductivity was observed with the addition of SrBi4Ti4O15 as filler to the (PEO)(8)-LiN(CF3SO2)(2) polymer salt complexes. Among the investigated samples (PEO)(8)-LiN(CF3SO2)(2) +10 wt% SrBi4Ti4O15 (citrate gel) polymer composite exhibits a maximum conductivity

Ionic conductivity and electrochemical stability of poly(methylmethacrylate)-poly(ethylene oxide) blend-ceramic fillers composites

The role of inorganic ceramic fillers namely nanosized A12O3 (15-25 nm) and TiO2 (10-14 nm and ferroelectric filler SrBi4Ti4O15 (SBTCIT) (0.5 m) synthesized by citrate gel technique (CIT) on the ionic conductivity and electrochemical properties of polymer blend 15 wt% PMMA+PEO8:LiC1O4 + 2 wt% EC/PC electrolytes were investigated. Enhancement in conductivity was obtained with a maximum of 0.72 x 10-5 S cm-1 at 21C for 2 wt% of SrBi4Ti4O15 (SBT CIT) composite polymer electrolyte. The lithium-ion transport number and the electrochemical stability of the composite polymer electrolytes at ambient temperature were analysed. An enhancement in electrochemical stability was observed for polymer composites containing 2 wt% if SrBi4Ti4O15 (SBT CIT) as fillers

Electrochemical studies on LiFe1-xCoxPO4/carbon composite cathode materials synthesized by citrate gel technique for lithium-ion batteries

LiFePO4/carbon and LiFe1-xCoxPO4/carbon (x = 0.02, 0.04, 0.08 and 0.1) composite cathode materials were synthesized by citrate gel technique. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to study the phase and morphology of un-doped and Co doped lithium iron phosphate/carbon composites. The SEM images revealed that the particles were agglomerated and the particle sizes were almost homogeneously distributed. The particle size was found to be between 200 and 300 nm from transmission electron microscopy. Cyclic voltammetric studies were taken to investigate the electrochemical performance of the prepared composite materials. The high intensity of the anodic and cathodic peaks indicates that Li-ions and electrons were participating actively in redox reactions due to the carbon coating. Charge/discharge studies carried out on a CR2032 coin cell revealed that the carbon coated LiFePO4/carbon composite exhibited an improved discharge capacity of 157 mAh/g at low rates. We found that cobalt doping does not have a favourable effect on the electrochemical performance of lithium iron phosphate cathode materials

Towards Efficient Energy Storage Materials: Lithium Intercalation/Organic Electrodes to Polymer Electrolytes—A Road Map

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PEDOT Radical Polymer with Synergetic Redox and Electrical Properties

The development of new redox polymers is being boosted by the increasing interest in the area of energy and health. The development of new polymers is needed to further advance new applications or improve the performance of actual devices such as batteries, supercapacitors, or drug delivery systems. Here we show the synthesis and characterization of a new polymer which combines the present most successful conjugated polymer backbone and the most successful redox active side group, i.e., poly­(3,4-ethylenedioxythiophene) (PEDOT), and a nitroxide stable radical. First, a derivative of the 3,4-ethylenedioxythiophene (EDOT) molecule with side nitroxide stable radical group (TEMPO) was synthesized. The electrochemical polymerization of the PEDOT-TEMPO monomer was investigated in detail using cyclic voltammetry, potential step, and constant current methods. Monomer and polymer were characterized by NMR, FTIR, matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS), electron spin resonance (ESR) spectroscopy, elemental analysis, cyclic voltammetry, and four-point probe conductivity. The new PEDOT-TEMPO radical polymer combines the electronic conductivity of the conjugated polythiophene backbone and redox properties of the nitroxide group. As an example of application, this redox active polymer was used as a conductive binder in lithium ion batteries. Good cycling stability with high Coulombic efficiency and increased cyclability at different rates were obtained using this polymer as a replacement of two ingredients: conductive carbon additive and polymeric binders

A Hierarchical Hybrid MXenes Interlayer with Triple Function for Room-Temperature Sodium-Sulfur Batteries

Room temperature sodium sulfur (RT Na-S) batteries with high theoretical energy density and low cost have recently gained extensive attention for potential large-scale energy storage applications. However, the shuttle effect of sodium polysulfides is still the main challenge that leads to poor cycling stability, which hinders the practical application of RT Na-S batteries. Herein, a multifunctional hybrid MXene interlayer is designed to stabilize the cycling performance of RT Na-S batteries. The hybrid MXene interlayer comprises a large-sized Ti3C2Tx nanosheets inner layer followed by a small-sized Mo2Ti2C3Tx nanoflake outer layer on the surface of the glass fiber (GF) separator. The large-sized Ti3C2Tx nanosheet inner layer provides an effective physical block and chemical confinement for the soluble polysulfides. The small-sized Mo2Ti2C3Tx outer layer offers an excellent polysulfide trapping capability and accelerates the reaction kinetics of polysulfide conversion, due to its superior electronic conductivity, large specific surface area, and Mo-rich catalytic surfaces. As a result, RT Na-S batteries with this hybrid MXene interlayer modified glass fiber separator deliver a stable cycling performance over 200 cycles at 1 C with an enhanced capacity retention of 71%. This unique structure design provides a novel strategy to develop 2D material-based functional interlayer for high-performance metal-sulfur batteries

Two-Dimensional Unilamellar Cation-Deficient Metal Oxide Nanosheet Superlattices for High-Rate Sodium Ion Energy Storage

Cation-deficient two-dimensional (2D) materials, especially atomically thin nanosheets, are highly promising electrode materials for electrochemical energy storage that undergo metal ion insertion reactions, yet they have rarely been achieved thus far. Here, we report a Ti-deficient 2D unilamellar lepidocrocite-type titanium oxide (Ti0.87O2) nanosheet superlattice for sodium storage. The superlattice composed of alternately restacked defective Ti0.87O2 and nitrogen-doped graphene monolayers exhibits an outstanding capacity of similar to 490 mA h g(-1) at 0.1 A g(-1), an ultralong cycle life of more than 10000 cycles with similar to 0.00058% capacity decay per cycle, and especially superior low-temperature performance (100 mA h g(-1) at 12.8 A g(-1) and -5 degrees C), presenting the best reported performance to date. A reversible Na+ ion intercalation mechanism without phase and structural change is verified by first-principles calculations and kinetics analysis. These results herald a promising strategy to utilize defective 2D materials for advanced energy storage applications © 2018 American Chemical Societ