デジタルマイクロ天秤による鉛蓄電池充放電反応のその場測定

概要

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Many electrode reactions have the mass change in addition to the charge transfer. In this study, a peculiar system was built and tested using a digital microbalance with the sensitivity of 10-5 g in order to measure in-situ the mass change of the active materials in a lead-acid battery during charge-discharge reaction. On close inspection by the Cu electrodeposition, the mass change in-site measured by the system, which was corrected on account of the buoyancy of the electrolyte to the electrode, was good agreement with the value obtained by the ex-situ measurement before and after the test. On the other hand, the higher the current density during electrolytic oxidation of Pb, the smaller the production rate of PbSO4 and the larger that of PbO2. High concentration of H2SO4 also brought larger amount of PbO2 for all the same quantity of electricity. Moreover, a part of the discharge product PbSO4 could not returned to the PbO2 during charge-discharge cycling, as the cycling proceeded. The difference of the electrode mass was eventually observed between the start of the cycling and the finish of the 3rd charging. The in-situ measurement also revealed that the reaction of PbSO4 to Pb and that of Pb to PbSO4 could start in the latter half of discharging and at the beginning of charging respectively.
2008-03-25