Article

A rechargeable lithium–oxygen battery with dual mediators stabilizing the carbon cathode

  • Nature Energy 2, Article number: 17118 (2017)
  • doi:10.1038/nenergy.2017.118
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Abstract

At the cathode of a Li–O2 battery, O2 is reduced to Li2O2 on discharge, the process being reversed on charge. Li2O2 is an insulating and insoluble solid, leading ultimately to low rates, low capacities and early cell death if formed on the cathode surface. Here we show that when using dual mediators, 2,5-Di-tert-butyl-1,4-benzoquinone [DBBQ] on discharge and 2,2,6,6-tetramethyl-1-piperidinyloxy [TEMPO] on charge, the electrochemistry at the cathode surface is decoupled from Li2O2 formation/decomposition in solution. Capacities of 2 mAh cmareal−2 at 1 mA cmareal−2 with low polarization on charge/discharge are demonstrated, and up to 40 mAh cmareal−2 at rates 1 mA cmareal−2 are anticipated if suitable gas diffusion electrodes can be devised. One of the major barriers to the progress of Li–O2 cells is decomposition of the carbon cathode. By forming/decomposing Li2O2 in solution and avoiding high charge potentials, the carbon instability is significantly mitigated (<0.008% decomposition per cycle compared with 0.12% without mediators).

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Acknowledgements

P.G.B. is indebted to the EPSRC, including the SUPERGEN programme, for financial support.

Author information

Author notes

    • Xiangwen Gao
    •  & Yuhui Chen

    These authors contributed equally to this work.

Affiliations

  1. Departments of Materials and Chemistry, Parks Road, University of Oxford, Oxford OX1 3PH, UK

    • Xiangwen Gao
    • , Yuhui Chen
    • , Lee R. Johnson
    • , Zarko P. Jovanov
    •  & Peter G. Bruce

Authors

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Contributions

X.G. and Y.C. designed experiments and analysed the data. X.G. performed electrochemical performance tests and characterizations with contributions from Z.P.J. Y.C. performed the 13C-carbon experiments and analysed the data. P.G.B., X.G., Y.C., L.R.J. and Z.P.J. interpreted the data. P.G.B. wrote the paper.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Peter G. Bruce.

Supplementary information

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    Supplementary Information

    Supplementary Figures 1–8