Energy is the determining factor of productivity and quality of living. Electric energy is the most used energy form and lack of reserve for it hinders widespread use of renewable energy technologies. Advancements in renewable energy technologies, electric vehicles and consumer electronics are highly dependent on developments of new battery technologies. High energy density, long service life, using benign and abundant materials are few of the key requirements for next generation batteries. A model, a mathematical description of the system, is an effective tool to predict the behavior of batteries under specific conditions, thus reducing cost and time for the development. A mathematical model using finite element method was designed to simulate the discharge behavior of an experimental nickel-zinc battery that includes composite zinc and commercial nickel electrodes. The model employs thermodynamic and kinetic expressions for porous electrodes considering the concentration dependency of battery characteristics. The effects of initial zinc and nickel concentrations, anodic transfer coefficients of zinc and nickel electrode reactions on the electrochemical performance of the battery have been simulated. The discharge voltage, electrode porosities, and species concentrations in electrodes as a function of model parameters and time have been evaluated. It is observed that the model results are consistent with the experiment results considering that the battery operation is limited with zinc concentration. Initial zinc concentration is the major determining factor on discharge duration. Nickel oxyhydroxide concentration affects voltage magnitude. Transfer coefficients have only limited effects on discharge voltage and concentrations.