Journal article
Li-O2 kinetic overpotentials: Tafel plots from experiment and first-principles theory
We report the current dependence of the fundamental kinetic overpotentials for Li-O2 discharge and charge (Tafel plots) that define the optimal cycle efficiency in a Li-air battery. Comparison of the unusual experimental Tafel plots obtained in a bulk electrolysis cell with those obtained by first-principles theory is semiquantitative.
The kinetic overpotentials for any practical current density are very small, considerably less than polarization losses due to iR drops from the cell impedance in Li-O2 batteries. If only the kinetic overpotentials were present, then a discharge-charge voltaic cycle efficiency of ∼85% should be possible at ∼10 mA/cm2 superficial current density in a battery of ∼0.1 m2 total cathode area.
We therefore suggest that minimizing the cell impedance is a more important problem than minimizing the kinetic overpotentials to develop higher current Li-air batteries.
Language: | English |
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Year: | 2013 |
Pages: | 556-560 |
ISSN: | 19487185 |
Types: | Journal article |
DOI: | 10.1021/jz400019y |