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Lithium Rechargeable Batteries (lithium + rechargeable_battery)
Selected AbstractsCombined First-Principle Calculations and Experimental Study on Multi-Component Olivine Cathode for Lithium Rechargeable BatteriesADVANCED FUNCTIONAL MATERIALS, Issue 20 2009Hyeokjo Gwon Abstract The electrochemical properties and phase stability of the multi-component olivine compound LiMn1/3Fe1/3Co1/3PO4 are studied experimentally and with first-principles calculation. The formation of a solid solution between LiMnPO4, LiFePO4, and LiCoPO4 at this composition is confirmed by XRD patterns and the calculated energy. The experimental and first-principle results indicate that there are three distinct regions in the electrochemical profile at quasi-open-circuit potentials of ,3.5,V, ,4.1,V, and ,4.7,V, which are attributed to Fe3+/Fe2+, Mn3+/Mn2+, and Co3+/Co2+ redox couples, respectively. However, exceptionally large polarization is observed only for the region near 4.1,V of Mn3+/Mn2+ redox couples, implying an intrinsic charge transfer problem. An ex situ XRD study reveals that the reversible one-phase reaction of Li extraction/insertion mechanism prevails, unexpectedly, for all lithium compositions of LixMn1/3Fe1/3Co1/3PO4 (0,,,x,,,1) at room temperature. This is the first demonstration that the well-ordered, non-nanocrystalline (less than 1% Li,M disorder and a few hundred nanometer size particle) olivine electrode can be operated solely in a one-phase mode. [source] A Critical Size of Silicon Nano-Anodes for Lithium Rechargeable Batteries,ANGEWANDTE CHEMIE, Issue 12 2010Hyejung Kim Feindispergierte Si-Nanokristalle von ungefähr 5, 10 und 20,nm Größe wurden bei hohem Druck und 380,°C in reversen Micellen hergestellt und als Anodenmaterial für Lithiumbatterien getestet. Die 10-nm-Nanokristalle wiesen eine Anfangs-Ladungskapazität y von 3380,mAh,g,1 auf, und selbst nach 40 Zyklen war die Kapazität nur auf 81,% gesunken, bei Kohlenstoffbeschichtung sogar nur auf 96,% (siehe Bild). [source] Lithium Batteries: (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 10 2009Mater. The cover picture is a scanning electron microscopy image of uncoated and 0.5 wt% TiO2 nanoparticle-coated LiCoO2 cathode particles, which are investigated in the research and development of lithium rechargeable batteries that require high power, high capacity, and high safety. TiO2 nanoparticles with sizes below 100 nm are mixed with LiCoO2 particles with an average particle size of 20,µm in a rotating jar at 200 rpm. The mixed particles are then fired at 1000°C for 5 h in air. The uncoated and 0.5 wt% coated particles show similar surface morphologies to each other. Despite the use of dry coating, Ti atoms appear to distribute uniformly throughout the particles. The advantage of this method is a simplified and cost-effective coating procedure, and these electrochemical enhancements can lead to versatile potential applications of the batteries, and provide breakthroughs in the power supply of mobile electronics. [source] Physical and Electrochemical Properties of PVdF-HFP/SiO2 -Based Polymer Electrolytes Prepared Using Dimethyl Acetamide Solvent and Water Non-SolventMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 8 2007Kwang Man Kim Abstract Poly[(vinylidene fluoride)- co -hexafluoropropylene]/SiO2 polymer electrolytes were prepared by a phase inversion technique using DMAc solvent and water non-solvent. Cast film electrolytes filled with the same amount of SiO2 using DMAc were also made to compare physical and electrochemical properties. DMAc had a higher solubility to PVdF-based polymers than NMP, and DMAc produced highly porous structures with bigger cavities and influenced the reduction of crystallinity. Due to the highly porous nature of phase inversion membranes, the uptake of electrolyte solution reached more than 400% and room-temperature ionic conductivity was more than 10,3 S,·,cm,1. All of the liquid absorbed, however, did not necessarily contribute to increases in ionic conductivity. This was due to the different conduction modes of lithium cations in a complicated porous structure. Comprehensively optimizing all the properties measured, the phase inversion membrane electrolytes with 10,30 wt.-% SiO2 were the best candidates for use as the polymer electrolyte of lithium rechargeable batteries. [source] | ||||||||||