Lithium-oxygen (Li-O2) batteries process the highest energy density (3505 Wh/kg based on the reaction Li+O2→Li2O2) among the rechargeable batteries and have been paid much attention. Their development is hindered by the large polarization and short cycling life. Herein, in virtue of the oxyhalogen-sulfur chemistry, our Li-O2 cells are performed similarly to the conventional Li-ion batteries. The charged and discharged potential profiles are almost overlapped in the voltage range of 2.8-3.0 V. When the specific capacity is limited to 500 mAh/g, stable long-term (&gt;250 cycles) cycling performance is achieved at 0.5 C. Analysis by Raman and X-ray photoelectron spectroscopy discloses a new mechanism: O is (de-)attached to sulfide cathode reversibly via the S=O chemical bonding. Upon discharge, the O2 is reduced, and the sulfide is oxidized. Inverse process occurs when the cell is charged. Our findings provide a new high-energy batteries system based on the oxyhalogen-sulfur chemistry and shed light on exploring other anion-redox for electrochemical devices.

Li-O2 batteries based on oxyhalogen-sulfur chemistry

253rd National Meeting (2017)

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