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Mechanism for Singlet Oxygen Production in Li-Ion and Metal–Air Batteries
journal contribution
posted on 2020-05-21, 22:04 authored by Gregory Houchins, Vikram Pande, Venkatasubramanian ViswanathanSinglet
oxygen has emerged as a real mystery puzzling battery science,
having been observed in Li–O2 and Na–O2 batteries, in conventional Li-ion batteries with NMC cathodes,
and during the oxidation of Li2CO3. The formation
of singlet oxygen has been directly linked to the degradation and
catastrophic fade seen in these battery chemistries. While there are
several proposed hypothesis for its origin, the exact mechanism for
the formation of singlet oxygen remains unclear. In this Letter, we
attempt to unify these findings by proposing a mechanism of singlet
oxygen production in metal–air and Li-ion batteries. We show
that a potential dependence of surface termination explains the onset
potentials of singlet oxygen release, and in all considered cases
the mechanism of singlet oxygen generation is through the chemical
disproportionation of the uncoordinated superoxide anion in solution;
therefore, the singlet oxygen yield is determined by the concentration
of free superoxide versus alkali superoxide ion pairs in solution.