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Dual-Functioning Molecular Carrier of Superoxide Radicals for Stable and Efficient Lithium-Oxygen Batteries

Cited 7 time in Web of Science Cited 5 time in Scopus
Issue Date
2020-10
Citation
Advanced Energy Materials, Vol.10 No.40, p. 1904187
Keywords
electron paramagnetic resonance;in situ differential electrochemical mass spectroscopy;lithium-oxygen batteries;stability;superoxide
Abstract
Low round-trip efficiency and poor cycle stability remain the major challenges associated with lithium-oxygen (Li-O-2) batteries. These issues are primarily triggered by or correlated to the radical species produced during the operation of Li-O(2)cells, which lead to significant deterioration of the electrolytes and air electrodes. Regulation of the reactivity of these radical species would thus open up opportunities to suppress such side reactions. Herein, a dual-functioning molecule that is capable of mitigating the reactivity of radical species produced in a Li-O(2)cell by reversibly forming stable intermediate complex during both the discharge and charge processes is introduced. Specifically, 5,5-dimethyl-1-pyrroline N-oxide (DMPO) is exploited, which has been widely used as a chemical agent to detect oxygen radicals, to induce the reversible formation of an intermediate complex, DMPO-O-2(-), in the presence of superoxide radicals. It is demonstrated that DMPO mediates the O-2(-)-involved electrochemical reaction, leading to significant suppression of side reactions and a remarkably improved oxygen efficiency. Unexpectedly, it is also observed that upon charging, DMPO actively scavenges the superoxides from the surface of discharge products, thus substantially lowering the charging overpotential. The combined radical mediation and scavenging of superoxides result in cycle stability of a practical Li-O(2)cell over 200 cycles with a specific capacity of 1000 mAh g(-1). The findings indicate the importance of controlling the reactivity of radical species and suggest a new pathway toward the realization of stable and efficient Li-O(2)batteries.
ISSN
1614-6832
URI
https://hdl.handle.net/10371/178477
DOI
https://doi.org/10.1002/aenm.201904187
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