Polarization characteristics of electrochemical battery hybrid system

The polarization characteristics of potential electrochemical components of an unregulated battery hybrid system were studied. The components under study included two lead-acid cells (2 Ah prismatic cell and a 1 Ah cylindrical cell), and a 1.7 Ah cylindrical nickel metal hydride cell as the high power density but low energy density component, and a 30 Ah zinc-air cell as the high energy density but moderate power density component. The prismatic lead-acid cell was found to have more favorable characteristics than the cylindrical design for an electrochemical battery hybrid system. In comparison to the lead-acid system, the nickel-metal hydride cell, because of its greater charge potential and current required, is not a good candidate for an unregulated hybrid system. The zinc-air system has desirable polarization characteristics for the high-energy hybrid component. Overall, under identical load and cut-off voltage, a hybrid system utilizing the zinc-air and lead-acid batteries provided 40% greater energy than a zinc-air/nickel-metal hybrid system, translating to longer operational time