A High Temperature Lithium-Oxygen/Air Fuel Cell Formulation

Abstract

The formulation presented in this paper has been developed for the design and performance analysis of a high temperature lithium/oxygen or air fuel cell. The formulation predicts the cell open-circuit voltage (EMF), thermodynamic efficiency; the lithium (fuel) fractional conversion and formation of the solid product (di-lithium monoxide) as a function of the cell operational time; the net cell-mass increase rate at a constant cell current; and the ratio of (the net cell-mass increase rate) to (its electric power delivery to an external electric load) as a function of the cell temperature. The numerical data calculated from the formulation predicts a decrease in the cell open-circuit voltage with an increase in the cell temperature. The cell open-circuit voltage is larger at 5bar than that at 1bar with air being the cell oxidant source over the temperature range of 298.15-1100 K. The cell ideal thermodynamic efficiency decreases with an increase in the cell operational temperature from about 94 to 77% over the temperature range mentioned above. Also, the ratio of [(the net cell-mass increase rate) to (the cell electric power delivery to an external electric load)] increases with an increase in the cell operational temperature. Finally, it is recommended that a physical system of the type sketched in Figure 1 be built for the acquisition of the open-circuit cell voltage as well as the operational cell voltage data for the constant cell current levels at the isothermal and isobaric conditions to validate the predictions of the presented formulation.