The effect of O2 concentration on the reaction mechanism in Li-O2 batteries
Artikel i vetenskaplig tidskrift, 2017

The promising lithium-oxygen battery chemistry presents a set of challenges that need to be solved if commercialization is ever to be realized. This study focuses on how the O2 reaction path is effected by the O2 concentration in the electrolyte. An electrochemical quartz crystal microbalance system was used to measure current, potential, and change in electrode mass simultaneously. It is concluded that the mass reversibility is O2 concentration dependent while the coulombic efficiency is not. The mass reversibility is higher at low O2 concentration meaning that more of the deposited Li2O2 is removed during oxidation in relation to the amount deposited during reduction. The first step of the reduction is the formation of soluble LiO2, which is then either reacting further at the electrode or being transported away from the electrode resulting in low current efficiency and low deposited mass per electrons transferred. During the oxidation, the first step involves de-lithiation of Li2O2 at low potential followed by bulk oxidation. The oxidation behavior is O2 concentration dependent, and this dependence is likely indirect as the O2 concentration effects the amount of discharge product formed during the reduction. The O2 concentration at different saturation pressures was determined using a mass spectrometer. It was found that the electrolyte follows Henry's law at the pressures used in the study. In conclusion, this study provides insight to the O2 concentration dependence and the preferred path of the O2 electrochemical reactions in lithium-oxygen batteries.

Electrochemical quartz crystal microbalance

O2 concentration dependence

Reaction mechanism

Mass spectrometer

Atomic force microscope

Non-aqueous lithium-oxygen battery

O2 saturation concentration

Författare

Jonas Lindberg

Kungliga Tekniska Högskolan (KTH)

Björn Wickman

Chalmers, Fysik, Kemisk fysik

Mårten Behm

Kungliga Tekniska Högskolan (KTH)

Ann Cornell

Kungliga Tekniska Högskolan (KTH)

Göran Lindbergh

Kungliga Tekniska Högskolan (KTH)

Journal of Electroanalytical Chemistry

1572-6657 (ISSN)

Vol. 797 1-7

Styrkeområden

Energi

Materialvetenskap

Ämneskategorier

Materialkemi

Annan kemiteknik

DOI

10.1016/j.jelechem.2017.05.005

Mer information

Senast uppdaterat

2018-02-26