The internal distributed physicochemical characteristics of a battery significantly affect its performance. However, these properties are difficult to measure experimentally. This study presents a validated three-dimensional (3D) battery model covering the conservation of charge, mass, and energy and the electrochemical reaction of a laminated 10 Ah lithium iron phosphate battery. Using this 3D battery model, the space and time distributions of the internal physicochemical properties of the battery are investigated. The results indicate that the maximum gradients of the properties are at the transition region between the tabs and electrode plates. Thus, the tabs in a battery should be reasonably designed. For this LiFePO4/Graphite battery, anode plays a more important role than cathode in the overall overpotential and is likely to be crucial in the sharp decrease of output voltage at the later discharge process. And a higher battery capacity can be obtained by increasing the amount of anode material.