Low-temperature structures of the lithium manganese spinels were determined using TOF neutron Rietveld analysis. The spinels LiMn2O4 with different values, (0.016, 0.040, and 0.132) showed the cubic-orthorhombic phase transitions, and the lattice distortion decreased with decreasing . Although no anomaly corresponding to the cubic-orthorhombic phase transition was observed in the DSC curve for ...

Porous solids have an important role in addressing some of the major energy-related problems facing society. Here we describe a porous solid, α-MnO2, with a hierarchical tetramodal pore size distribution spanning the micro-, meso- and macro pore range, centred at 0.48, 4.0, 18 and 70  nm. The hierarchical tetramodal structure is generated by the presence of potassium ions in the precursor solut...

We describe synchroton based X-ray diffraction techniques and issues related to in situ studies of intercalation processes in battery electrodes. We then demonstrate the utility of this technique, through a study of two batches of LiMn2O4 cathode materials. The structural evolution of these spinel materials was monitored in situ during the initial charge of these electrodes in actual battery ce...

This dissertation reports on the synthesis, structural and thermal characterization and electrical and thermal transport properties of a variety of strongly correlated spinels. General structure property relationships for electrical and thermal transport are discussed. However, the relationship between thermopower and features of the crystal structure such as spin, crystal field, anti-site diso...

Anatase TiO2 modified FeS nanowires assembled by numerous nanosheets were synthesized by using a typical hydrothermal method. The carbon-free nanocoated composite electrodes exhibit improved reversible capacity of 510 mAh g(-1) after 100 discharge/charge cycles at 200 mA g(-1), much higher than that of the pristine FeS nanostructures, and long-term cycling stability with little performance degr...

Este trabalho reporta medidas de condutividade iônica realizadas para o LiHf2(PO4)3 calcinado a 1100 °C. As respostas devidas aos grãos in te rior e junção puderam ser identificadas tanto nas curvas de impedância, como na parte real das curvas de condutividade vs. freqüência. A energia de ativação, associada ao movi men to dos íons Li no in te rior dos grãos, é 0,33 eV, enquanto que aquela asso...

To understand inhomogeneous reactions perpendicular to the current collector in an electrode for batteries, a method combining operando synchrotron X-ray diffraction and two-layer electrodes with different porosities is developed. The two layers are built using two different active materials (LiNi0.80Co0.15Al0.05O2 and LiMn2O4), therefore, tracing each diffraction pattern reveals which active m...

Cathode degradation is a key factor that limits the lifetime of Li-ion batteries. To identify functional coatings that can suppress this degradation, we present a high-throughput density functional theory based framework which consists of reaction models that describe thermodynamic and electrochemical stabilities, and acid-scavenging capabilities of materials. Screening more than 130,000 oxygen...