High performance PEO-based polymer electrolytes and their application in rechargeable lithium polymer batteries

Solvent-free, lithium-ion-conducting, composite polymer electrolytes have been prepared by a double dispersion of an anion trapping compound, i.e., calyx(6)pyrrole, CP and a ceramic filler, i.e., super acid zirconia, S-ZrO₂ in a poly(ethylene oxide)-lithium bis(oxalate) borate, PEO–LiBOB matrix. The characterization, based on differential thermal analysis and electrochemical analysis, showed that while the addition of the S-ZrO₂ has scarce influence on the transport properties of the composite electrolyte, the unique combination of the anion-trapping compound, CP, with the large anion lithium salt, LiBOB, greatly enhances the value of the lithium transference number without depressing the overall ionic conductivity. These unique properties make polymer electrolytes, such as PEO₂₀LiBOB(CP)_0.125, of practical interest, as in fact confirmed by tests carried out on lithium battery prototypes.     

Solving central charge constraints in extended super-Yang-Mills theories

We obtain a local lagrangian involving unconstrained fields for the N = 2 and 4 non-abelian super-Yang-Mills in the central charge version obtained by dimensional reduction by Legendre transformation from five dimensions. The resulting Lorentz and supersymmetry transformations do possess non-locality, however.     

Mechanochemical synthesis and electrochemical properties of nanostructured electrode materials for Li ion batteries

We focus on the synthesis by ball milling and on the electrochemical characterization of nanocrystalline bimetallic and composite materials to be employed as anodes in Li ion batteries. Ni₃Sn₄ and Ni₃Sn₂ based compounds were obtained by ball milling of three different Ni–Sn mixtures. The properties of the resulting anodes for Li ion batteries were evaluated as a function of composition. Moreover, a biphasic system is presented, with CoSn₂ and CoSn type structures, arising from the synthesis of the Sn₃₁Co₂₈C₄₁ composition. When cycled in a Li cell, this material showed a high reversible specific capacity, about 450 mA h g⁻¹, and a very good electrochemical and structural stability, making it of interest for application purposes. Contribution to the Fall Meeting of the European Materials Research Society, Symposium D: 9th International Symposium on Electrochemical–Chemical Reactivity of Metastable Materials, Warsaw, 17th–21st September, 2007.     

Hybrid membranes based on sulfated titania nanoparticles as low-cost proton conductors

This work reports on a novel, hybrid solid-state membrane based on sulfated titania nanoparticles stabilized by a polyvinylidene fluoride–hexafluoropropylene copolymer. A fast solvent-casting technique was adopted as a valid alternative to a fully dry, hot-pressing preparation procedure. Self-standing, flexible membranes with high proton conductivity were obtained.     

A low-cost,high-energy polymer lithium-sulfur cell using a composite electrode and polyethylene oxide (PEO) electrolyte

Herein, we report a polymer cell using high-energy lithium metal anode, a composite sulfur-carbon cathode, and polyethylene oxide (PEO)-lithium trifluoromethan sulfonate (LiCF₃SO₃) electrolyte. The limited cost of raw materials as well as the very simple synthetic procedures, involving planetary ball milling (for S-C cathode) and solvent casting (for PEO-electrolyte), are expected to reflect into remarkable reduction of the economic impact of the proposed battery. Furthermore, the high energy of the Li-S cell and safety of the polymer configuration represent additional bonuses of the system. The S-C material, revealing a maximum capacity as high as 700 mAh g^?1 in liquid electrolyte, is employed in a lithium-sulfur battery with the polymer configuration. The polymer cell delivers a capacity of 450 mAh g^?1 at a voltage of about 2 V; hence, a theoretical energy density of 900 Wh kg^?1 that may reflect into a high practical value, suitable for energy storage applications.     

An advanced lithium ion battery based on high performance electrode materials

In this paper we report the study of a high capacity Sn-C nanostructured anode and of a high rate, high voltage Li[Ni(0.45)Co(0.1)Mn(1.45)]O(4) spinel cathode. We have combined these anode and cathode materials in an advanced lithium ion battery that, by exploiting this new chemistry, offers excellent performances in terms of cycling life, i.e., ca. 100 high rate cycles, of rate capability, operating at 5C and still keeping more than 85% of the initial capacity, and of energy density, expected to be of the order of 170 Wh kg(-1). These unique features make the battery a very promising energy storage for powering low or zero emission HEV or EV vehicles.     

Synthesis of pyrazolo[1,5-a]pyridines and pyrazolo[1,5-c]pyrimidines by reaction of heterocyclic amidrazones with 1,3-dicarbonyl compounds

1,3-Dicarbonyl compounds 2 react with 1-amino-2(1H)-pyridin-2-imines or 1-amino-2(1H)-pyrimidin-2-imines 1 giving new pyrazolo[1,5-a]pyridines or pyrazolo[1,5-c]pyrimidines 5 respectively by addition, oxidation and condensation. Isolation of an intermediate 3 shows that surprisingly the addition of the CH acidic 1,3 -dicarbonyl compound to position 6 of the pyrimidine 1 is the initial step.     

Bathochromic 1-amino-2(1H)-pyrimidinimines and hydrazones by substitution/dimroth rearrangement of 1-amino-2-methylthiopyrimidinium salts

1-Amino-2-methylthiopyrimidinium salts 1 and 9 react with hydrazines 2 or alkylamines 6 by substitution of the methylthio group and Dimroth rearrangement affording violet or purple 2(1H)-pyrimidinehydrazones 5 and 7 or orange hydrazones 8 , rather than the non-rearranged hydrazones 10 or zwitterionic 1-amido-2-hydrazinopyrimidinium ylides 4 as previously reported.