EXPERIMENTAL STUDY OF THE BEHAVIOUR OF A 10Ah SODIUM SULPHUR BATTERY (NaS) CELL

Sodium sulphur batteries (NaS) are ideally suited to constant temperature energy storage because they have a good high energy density, it is one of the main batteries used for energy storage in medium to large scale storage. There has been a surge in the popularity of NaS batteries also known as molten metal batteries in recent years owing to their high specific energy density capacity and long-life cycle in energy storage.
This research is centred on a feasibility study of an electrical energy storage receiver / solar parabolic trough collector developed at the University of Leeds. The receiver is a heat collecting device with integrated thermal storage of NaS batteries. This research is looking at the battery cell at how they cope with hybridization in a renewable system with solar thermal. The work is on the heat treatment to the battery cell from room temperature to 360°C and was undertaken in collaboration with and at the request of the company Ionotec ltd who provided the batteries for the research, presently the current literature only refers to experimentation when the cell is at operational temperature, this work is looking at taking the battery cell up from room temperate to operating temperature, charge, and discharge.
This thesis presents a background into energy storage and the reason for incorporating renewable energy into the energy generation mix. Also presented is a brief overview of two types of energy storage technologies and battery charging methods. In addition, presented is a summary of work done in preparation for experimental work and recommissioning of the rig.
The stand-alone system consisting of the sodium sulphur cell and a furnace was constructed. The system was designed to fit the test parameters developed for the experiments. An automated monitoring system was developed based on the initial system with LabView. Heating trials and charging and discharging of the sodium sulphur cell were conducted using the stand-alone system and results were obtained. The system was tested and validated to the results. Three Heating rates of 1°C/min, 2°C/min and 3°C/min of the NaS cell were developed and experimented with successfully. At all three rates at operating temperature, they showed an open circuit voltage indicating a fully functioning cell.
Findings were subsequently analysed, and conclusions are drawn. Recommendations based on the findings were made regarding prospective improvements to the system.