Alpha-MnO2 As a Hybrid Li-Ion/Li-O2 Battery Material -- Operando Characterization and First Principles Modeling
Authors: Yang Zhenzhen , Ford Denise , Kim Hacksung , Ren Yang , Park Joong Sun , Johnson Christopher , Chan Maria K. Y. , Thackeray Michael M. 
Published: February 2020

Hollandite α-MnO2, with an open tunnel structure, is of interest as a cathode material for 3 V lithium batteries [1,2] and as an electrocatalyst for Li-O2 cells [3]. We recently proposed [4] that α-MnO2 belong to a class of materials that can be used as the cathode in hybrid Li-ion/Li-oxygen battery systems, which can incorporate/release both lithium and oxygen during cycling with redox reactions occurring on both the transition metal ions and oxygen ions of the electrode. In this talk, we will present in-situ and operando characterization and first principles modeling results of α-MnO2 during electrochemical cycling in conventional lithium cells and in Li-O2 cells [5,6]. Operando synchrotron x-ray diffraction (XRD) results, combined with first principles density functional theory (DFT) modeling, indicate insertion of lithium and oxygen into, as well as partial removal of these species from, the tunnel structure during cycling. On heating hydrated α-MnO2, in-situ XRD and Raman studies provide information about structural changes and diffusional properties of the oxygen species in the tunnel structure. DFT studies find low diffusion barriers for H2O and H3O+species in the tunnel. The implications of the results on other high-capacity, hybrid Li-ion/Li-oxygen materials will be discussed.

Acknowledgements

This work was supported as a part of the Center for Electrochemical Energy Science, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Basic Energy Sciences under award number DE-AC02–06CH11. Use of the Advanced Photon Source, a US DOE Office of Science User Facility operated by Argonne National Laboratory, was supported by DOE under Contract No. DE-AC02-06CH11357. Use of the Center for Nanoscale Materials, an Office of Science user facility, was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

References

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