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EIS diagnostics of aged Li-ion batteries

High-power batteries with long cycling life and adequate storage behaviour are needed as energy sources devices for (hybrid) electric vehicles and lithium-ion rechargeable cells are the most promising candidates. In this work, Li-ion cells with a nominal capacity of 10 Ah were studied. Electrochemical impedance spectroscopy (EIS) was used for studying the cycling ageing effect on discharge capacity fade. EIS me...

Characterisation and performance studies of a LiFePO4 cathode material synthesi...

Lithium iron phosphate with incorporated carbon, LiFePO4-C, was synthesized by the microwave-assisted method. X-ray diffraction analyses showed higher crystallization degrees for samples submitted to higher irradiation times. A particle-agglomerated morphology was associated as revealed by scanning electron microscopy. The electrochemical character-istics of a composite cathode containing the synthesized produc...

The effect of chloride as catalyst layer contaminant on the degradation of PEMFCs

In this work, the effect of chloride as a catalyst contaminant was studied on the performance and durability of a low power open-cathode fuel cell, intended for passive management of water. In an ex-situ study, cyclic voltammetry was used to assess the redox behaviour of platinum in chloride contaminated solutions at room temperature.The cell was operated integrating a range of relative humidity (RH) from ~30 t...

Degradation of a Lithium Iron Phosphate based Cathode in Lithium-ion Batteries ...

Degradation of lithium Iron phosphate-based cathode in lithium-ion batteries: a...

Commercial Li-ion batteries were studied in view to investigate the degradation of the positive electrode in an end-of-life battery condition. Post-mortem analyses were performed by using SEM and DRX techniques; structural and morphological changes after prolonged cycling were evaluated comparatively to a fresh cathode sample. The cycling procedure based on a constant current (CC)/constant voltage (CV) charge a...

Electrólitos poliméricos para sistemas electroquímicos de energia

Tese apresentada no Instituto Superior Técnico para obtenção do Grau de Doutor em Engenharia Química ; Na primeira parte do trabalho são sintetizados filmes poliméricos de poli(óxido de etileno) dopado com cloreto de zinco, iodeto de zinco, cloreto de níquel ou iodeto de níquel. Os filmes, com espessuras na gama 50-100μm, são caracterizados morfológica e microestruturalmente, procedendo-se também à análise do...

Electrochemical characterization of poly(ethylene oxide)- zinc chloride system ...

The system PEOnZnCl2 with n=4-16 was studied in view of its potential application in a solid state rechargeable zinc battery. A.c. conductivity and cationic transference number measurements, in the temperature range 20-150ºC, were performed and the electrochemical stability window was established for the polymer electrolyte with n=4 composition. The ionic conductivity, σ, of this film, follows a VTF behaviour, ...