Rational design of redox mediators for advanced Li–O2 batteries

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The discovery of effective catalysts is an important step towards achieving Li–O2 batteries with long cycle life and high round-trip efficiency. Soluble-type catalysts or redox mediators (RMs) possess great advantages over conventional solid catalysts, generally exhibiting much higher efficiency. Here, we select a series of organic RM candidates as a model system to identify the key descriptor in determining the catalytic activities and stabilities in Li–O2 cells. It is revealed that the level of ionization energies, readily available parameters from a database of the molecules, can serve such a role when comparing with the formation energy of Li2O2 and the highest occupied molecular orbital energy of the electrolyte. It is demonstrated that they are critical in reducing the overpotential and improving the stability of Li–O2 cells, respectively. Accordingly, we propose a general principle for designing feasible catalysts and report a RM, dimethylphenazine, with a remarkably low overpotential and high stability.

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Figure 1: Role of RM for Li–O2 batteries.
Figure 2: Electrochemical properties of various RMs.
Figure 3: Gas analyses on effect of RMs.
Figure 4: Molecular orbital energies of RMs and TEGDME.
Figure 5: Cyclic voltammetry of RMs.
Figure 6: Effects of DMPZ as a catalyst for Li–O2 batteries.


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This work was supported by the HMC (Hyundai Motor Company), the Project Code (IBS-R006-G1), and the National Research Foundation of Korea(NRF) grant funded by the Korean Government(MSIP) (No. 2015R1A2A1A10055991). Y.Z. and K.C. acknowledge the Global Frontier R&D Program on Center for Multiscale Energy System (NRF-2011-0031571).

Author information

H.-D.L. and Y.Z. designed the experiments with help from J.H., J.K., H.G., Y.K., M.L. and K.C. The computations were performed by B.L. The original idea was conceived by K.K., who supervised all the experiments and calculations. All the authors discussed the results and contributed to preparing the manuscript.

Correspondence to Kyeongjae Cho or Kisuk Kang.

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Supplementary Figures 1–18, Supplementary Tables 1–2, Supplementary Notes 1–9, Supplementary References. (PDF 2205 kb)

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Lim, H., Lee, B., Zheng, Y. et al. Rational design of redox mediators for advanced Li–O2 batteries. Nat Energy 1, 16066 (2016) doi:10.1038/nenergy.2016.66

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