The Lithium-air battery has captured so much interest and been considered as a promising candidate for the future renewable energy sources because of its high specific energy density comparable to gasoline. But unfortunately, the maximum amount of the lithium metal utilized is limited because of the tunnel blockage and surface coverage inside cathode, which are caused by insoluble lithium composite generated at cathode. In other words, the total energy capacity is restricted by the cathode under adequate lithium. So if we can fully understand how the deposits work on the cathode, we are supposed to develop a better cathode, which can hold more products per unit volume, with immensely higher energy capacity per unit cathode volume. This paper describes a surface coverage model and two relative dominating effects, electrode passivation and transport resistance. By using the electron conservation combined with experimental formula from previous works, we could investigate how much the insoluble there is and the coverage coefficient used to evaluate what degree deposits damage the effectivity of cathode to. We could use the coverage coefficient to describe the effective surface area under different stage of precipitation. We may go further to obtain the oxygen profile by taking the oxygen transport equation into account. Then we have a chance to use the above model to formulate the loss of effective voltage and total energy capacity. We could eventually split the voltage loss into 2 pieces, one caused by electrode passivation and another caused by oxygen transport resistance. We can compare them to find out which one is the prime force to kill the battery, or that they cooperate together. We can also know how much deposits the cathode can be filled with before exhausted. Then the total energy capacity is ready to come out by integrating the voltage along the time under constant current. By looking into the integral, there are actually three parts, which are the capacity without considering voltage loss effect, and two capacity losses solely considering the voltage loss from the electrode passivation or oxygen transport resistance respectively. If we compare these different part, we could have a knowledge of whether the capacity loss is immense enough to be cared about, or which kind of loss costs more. To validate our model, we will also perform the experiments by using our sandwich cell to get the discharging curve, which will be used to validate our model by comparing the voltage loss and energy capacity loss. The sandwich cell structure from bottom to top is: bottom frame, aluminum foil, lithium metal, separator, rubble sealing ring, top frame with air window and electrolyte pool on top, and cathode. The whole cell is assembled by using screws. We could get open circuit voltage and discharging curves under different current. The data will be used to validate and improve our model mentioned above.