Fundamental in-situ and ex-situ studies of energy storage related materials including different applications of voltammetry

Abstract: This thesis is a summary and discussion of eight papers dealing with failures and structural aspects of Ni-Cd industrial pocket plate batteries, applications of voltammetry in adsorption studies on goethite (a-FeOOH) surfaces and synthesis and characterisation of nanostructured carbons. The work consists of different areas of chemistry; electrochemistry, structural chemistry and solution chemistry. Several experimental methods have been used; voltammetric methods, potentiometric titrations, X-ray diffraction methods, SEM, EDS, TEM and electrical testing.An in-situ X-ray diffraction method was developed to study the positive active material in the Ni-Cd industrial pocket plate battery. Voltammetry was used to study the battery materials electrochemically. The literature structural model of b-NiOOH (charged positive material) was questioned, the complexity of the positive material was shown and a new positive discharged phase of b-Ni(OH)2 was observed in this study. The failures of the batteries investigated were mainly connected to the presence of graphite in the positive electrodes and the extent of carbonation.The voltammetric technique, anodic stripping voltammetry, was thoroughly studied and was found to work satisfactory for determination of low metal ion concentrations in aqueous solution, as well as in goethite suspensions at different pH, using a mercury plated GC electrode and a Teflon cell. It was shown that the recently developed equilibrium models for Pb(II), Zn(II) and Cu(II) complexation on goethite at different pH could be used to predict the speciation in a wide concentration range, in single-metal as well as in the different two-metal systems.A chlorination synthesis method, by which it may be possible to produce bulk amounts, was used in order to produce nanostructured carbons. The initial carbide structure and the synthesis temperature were important parameters to determine the final carbon structure. The carbon structure formed from Al4C3 and CaC2 showed a nanoporous amorphous structure at low temperatures (400 oC) and at elevated temperatures (400 - 1000 oC) the structure became more graphitic. At intermediate temperatures (700 oC) the carbon from Al4C3 also showed a nanotube like structure (nanobarrels).