Abstract
In electric vehicles, reliable estimation of the state-of-charge (SoC) is crucial to determine the remaining capacity, but the electrochemical
processes in metal-O2 batteries are very different to the Li-ion batteries used today, and current SoC-estimation methods
prove insufficient. In Li-O2 batteries, the capacity is highly dependent on the discharge rate, since different current densities enable
different growth mechanisms of Li2O2, and an on-board calibration of the SoC is therefore needed. Such a calibration is typically
performed by measuring the open-circuit voltage (OCV), but as the OCV of many metal-O2 battery does not change as a function
of capacity, this method cannot be used. In this manuscript, we propose a method, based on a single-frequency electrochemical
impedance measurement, to estimate the remaining capacity and assess the state-of-health of reversible metal-O2 batteries by calculating
the capacitance of the positive electrode where the discharge products are formed. The results from experiments on Li-O2
batteries show that the capacitance is a good measure of the remaining capacity and that the SoC estimation can be improved
significantly by the calibration.
Original language | English |
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Journal | Journal of The Electrochemical Society |
Volume | 162 |
Issue number | 10 |
Pages (from-to) | A2075-A2079 |
ISSN | 0013-4651 |
DOIs | |
Publication status | Published - 2015 |