Metal Foam Electrodes Incorporated with Molten Active Materials for Thermal Batteries

A Li-Si/FeS₂ electrochemical system, which is widely used for thermal batteries, has limited energy density and power capability due to the partial utilization of the active materials. A single cell with a molten lithium anode or a molten sulfur cathode has a high energy density with a high open circuit voltage compared to that with a Li-Si/FeS₂ couple. The main challenges in the molten electrodes arise from the instability of liquid active materials which can directly react with the other electrode and results in catastrophic thermal runaways, such as vent, fire or even explosion. For the practical application to thermal batteries which operates at above the melting point of the active electrode materials, the immobilization of the molten electrode is inevitably required. The combination of the porous metal foams with liquid active materials is found to be quite effective solution to attain unconventionally high energy density as well as high power capability. In this study, highly conductive nickel foam electrodes are incorporated with pure lithium or sulfur. The electrochemical characteristics are investigated along with the single cell tests and the microstructural analysis.