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<p>Metal hydrides hydrogen storage materials have the ability to reversibly absorb and release large amounts of hydrogen at low temperature and pressure. In this study, metal hydride materialsemployed as negative electrodes in Ni-MH batteries are investigated. Attention is on AB5 alloys due to their intermediate thermodynamic properties. However, AB5 alloys a have&nbsp / tendency of forming oxide film on their surface which inhibits hydrogen dissociation and penetration into interstitial sites leading to reduced capacity. To redeem this, the materials were micro-encapsulated by electroless deposition with immersion in Pd and Pt baths. PGMs were found to increase activation, electrochemical activity and H2 sorption kinetics of the MH alloys. Between the two catalysts the one which displayed better performance was chosen. The materials were characterized by X-ray difractommetry, and the alloys presented hexagonal CaCu5 &ndash / type&nbsp / structure of symmetry P6/mmm. No extra phases were found, all the modified electrodes displayed the same behavior as the parent material. No shift or change in peaks which corresponded to Pd or Pt were observed. Scanning Electron Microscopy showed surface morphology of the materials modified with Pd and Pt particles, the effect of using different reducing agents (i.e., N2H4 and NaH2PO2), and alloys functionalized with &gamma / -aminosopropyltrietheosilane solution prior to Pd deposition. From all the surface modified alloys, Pt and Pd particles were observed on the&nbsp / surface of the AB5 alloys. Surface modification without pre-functionalization had non-uniform coatings, but the prefunctionalized exhibited more uniform coatings. Energy dispersive X-ray Spectroscopy and Atomic Absorption Spectroscopy determined loading of the Pt and Pd on the surface of all the alloys, and the results were as follows: EDS ( Pt 13.41 and Pd 31.08wt%), AAS (Pt 0.11 and Pd 0.78wt%). Checking effect of using different reducing agents N2H4 and NaH2PO2 for electroless Pd plating the results were as follows: EDS (AB5_N2H4_Pd- 7.57 and AB5_NaH2PO2_Pd- 31.08wt%), AAS (AB5_N2H4_Pd- 11.27 and AB5_NaH2PO2_Pd- 0.78wt%). For the AB5 alloys pre-functionalized with &gamma / -APTES, the results were: EDS (10.24wt%) and AAS (0.34wt%). Electrochemical characterization was carried out by charge/discharge cycling controlled via potential to test the AB5 alloy. Overpotential for unmodified, Pt and Pd modified&nbsp / electrodes were -1.1V, -1.24V, and -1.60V, respectively. Both modified electrodes showed discharge overpotentials at lower values implying higher specific power for the battery in comparison with the unmodified electrodes. However, Pd electrode exhibited higher specific power than Pt. To check the effect of the reducing agent the results were as follows: AB5_ N2H4_Pd (0.4V) and AB5_NaH2PO2_Pd (-0.2V), sodium hypophosphite based alloy showing lower overpotential values, implying it had higher specific power than hydrazine based bath. Alloy prefunctionalized with &gamma / -APTES, the overpotential was (0.28V), which was higher than -0.2V of the alloy without pre-functionalization, which means pre-functionalization with &gamma / -APTES did not improve the performance of the alloy electrode. Polarization resistance of the electrodes was investigated with Electrochemical Impedance Spectroscopy. The unmodified alloy showed high resistance of&nbsp / 21.6884 while, both Pt and Pd modified electrodes exhibited decrease 14.7397 and 12.1061 respectively, showing increase in charge transfer for the modified electrodes. Investigating the effect of the reducing agent, the alloys exhibited the following results: (N2H4 97.8619 and NaH2PO2 12.1061) based bath. Alloy pre-functionalized with &gamma / -APTES displayed the&nbsp / resistance of 9.3128. Cyclic Voltammetry was also used to study the electrochemical activity of the alloy electrodes. The voltammograms obtained displayed the anodic current peak at -0.64V&nbsp / o -0.65V for the Pt and Pd modified electrodes, respectively. Furthermore, the electrode which was not coated with Pt or Pd the current peak occurred at -0.59V. The Pd and Pt coated&nbsp / alloy electrodes represented lower discharge overpotentials, which are important to improve the battery performance. Similar results were also observed with alloy electrodes Pd modified&nbsp / using N2H4 (-0.64V) and NaH2PO2 (-0.65V). For the electrode modified with and without &gamma / -APTES the over potentials were the same (-0.65V). PGM deposition has shown to significantly&nbsp / improve activation and hydrogen sorption performance and increased the electro-catalytic activity of these alloy electrodes. Modified electrodes gave better performance than the unmodified&nbsp / electrodes. As a result, Pd was chosen as the better catalyst for the modification of AB5 alloy. Based on the results, it was concluded that Pd electroless plated using NaH2PO2 reducing agent&nbsp / had better performance than electroless plating using N2H4 as the reducing agent. Alloy electrode pre-functionalized with &gamma / -APTES gave inconsistent results, and this phenomenon needs to&nbsp / be further investigated. In conclusion, the alloy modified with Pd employing NaH2PO2 based electroless plating bath exhibited consistent results, and was found to be suitable candidate for&nbsp / use in Ni-MH batteries.</p>

Batteries are important energy storage devices and are used in different applica- tions. The purpose of this thesis is to study behavior and characteristics of batter- ies when used in system-level design process. In addition, the use of hardware-in- loop (HIL) simulation of batteries for power system applications is studied. The thesis also aims to investigate the ability of HIL in alleviating the need for extensive and detailed modeling of battery storage systems and to improve the accuracy of the simulation of systems where they are used. The major problem of using battery models is that they are greatly aff ected by external factors such as temperature and history of the charge/discharge regimes. An HIL scheme eliminates the need for mathematical modeling of batteries by interfacing them directly to the simula- tor, where charging and discharging regimes, state of charge estimation methods and efficiency can be investigated.

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A survey of cured fish establishments in 5 countries of South East Asia, revealed that cured fish is a nutritionally and economically important commodity in the region and that insect infestation, in particular blowfly infestation during processing and dermestid beetle infestation during storage, are major causes of losses in cured fish. Many processors have responded by illegally applying household and agricultural insecticides to their fish. Field investigations in Indonesia and Thailand, identified Chrysomya megacephala (Fab.) as the most widespread cause of infestation during processing. Lucilia caprina (Wied.) was also a common cause of infestation. Dermestes maculatus (Degeer), D. carnivorus (Fab.), D. ater (Degeer) and Piophila casei (L.), were the most common causes of infestation during storage. These species were able to tolerate the relatively high salt concentrations of the processed fish. Field infestation reduction trials, demonstrated that salting the fish for an extended period failed to provide protection against insect infestation. Guarding the salting tank with a closely fitting lid, prevented blowfly infestation during salting. Flyscreens were found to reduce blowfly infestation during drying, but the design used, presented practical difficulties and was not acceptable to the processor. The pyrethroid insecticide Fastac (alphacypermethrin), prevented blowfly infestation during processing at concentrations as low as 0.00.3% and had a marked repellent effect against blowflies at a concentration of 0.001%. Fastac, applied at a concentration of 0.006%, protected fish against dermestid beetle infestation and damage. Fastac residues in fish treated with a 0.006% dip decreased to less than 2 rag/kg after drying and 1 week's storage. The pyrethroid insecticide deltamethrin, prevented insect infestation during processing and storage, when applied as a 0.003% dip before drying. The FAO/WHO approved insecticide piriraiphos-methyl, reduced blowfly infestation and prevented damage during processing and reduced dermestid beetle infestation during storage, when applied as a 0.03% dip before drying. This treatment resulted in residues, after processing, that were within the FAO/WHO maximum residue limit of 10 mg/kg.Spray applications of pirimiphos-methyl, at dosages of 5-20 mg/kg and deltaraethrin, at dosages of 1-3 mg/kg, were effective in reducing dermestid beetle infestation of smoked fish during storage. Laboratory investigations demonstrated that C. megacephala produced similar numbers of male and female offspring and that there was no difference between the mortalities of the 2 sexes. Female flies greatly outnumbered male flies at the processing site. Mean lifespans of C. megacephala cage populations ranged from 47-54 days and the maximum survival time ranged from 80-98 days. C. megacephala eggs matured within 3 weeks of adult emergence and the mean egg count for the adult female flies was 221.The presence of C. megacephala eggs on fish, stimulated oviposition by C. megacephala and freshly laid eggs were found to have a higher stimulatory effect than eggs which had been previously boiled. Fish being salted exerted a marked, differential attractive effect on gravid, female flies. When presented with fish of a range of salt concentrations, C. megacephala preferentially oviposited on the fish with the lowest salt concentration. In the absence of choice, C. megacephala readily oviposited on fish with relatively high salt contents of 30-40% (dwb). A feeding medium salt content of 33.8% was necessary to significantly reduce larval growth rate and salt contents in excess of 39.5% were necessary to obtain high larval mortalities. Salt contents of up to 39.5% had no effect on pupal mortality.

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Complex spinel-structure oxides based on Li₂MM'₃O₈ and LiMM'O₄ have been systematically investigated on the basis of solid state chemistry and thermodynamics, and are found to constitute a novel family of cathode materials for 5 V lithium batteries. We have targeted lithium cathode materials that operate over 5 V, linked to large capacity and good cycling stability. The spinels prepared by solid state synthesis have been characterised using powder X-ray and neutron diffraction, impedance measurements, thermal analyses, magnetic measurements, XANES spectroscopy, Mossbauer spectroscopy and electrochemical measurements. In a single lithium cell, Li₂CoMn₃O₈ and LiCoMnO₄ are shown to be the first cathode materials to operate at discharge voltages over 5 V; Li₂FeMn₃O₈ operates at a discharge plateau commencing at 5 V and centred on 4.9 V, offering potentially great economic and environmental advantages as a lithium cathode. LiCoMnO₄ exhibits a discharge capacity of <I>ca</I>. 95 mAhg^-1 at a long plateau centred on 5.0 V in a cell, Li/LiPF₆, propylene carbonate / LiCoMnO₄, and therefore has superior energy density to LiMn₂O₄, the cathode material used in state-of-the-art cells. This renders LiCoMnO₄ potentially very attractive as a cathode material in practical 5 V lithium battery systems.

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