Issue 13, 2019

Understanding the electrochemical potential and diffusivity of MnO/C nanocomposites at various charge/discharge states

Abstract

Li-ion diffusion and lithiation kinetics in MnO/C nanocomposites were systematically investigated by monitoring the change in the charge transfer resistance and the ion diffusion coefficient, and the kinetically predominant process at various charge/discharge states. Crystal field analysis and density functional theory (DFT) calculations were introduced to reveal the relationship between the electronic structure of the phase compositions, the displayed electrochemical potential and its profile. The split 3d orbitals in the Mn ion determine the ordering of the electron migration and energy difference, leading to the different potential profiles in the lithiated/delithiated process. The phase compositions strongly affect the intrinsic properties of the MnO/C nanocomposites, increasing the ion diffusion coefficient from ∼10−15 to 10−11 cm2 s−1 when the electrode progressed from the fully charged to fully discharged state, while both the surface redox reaction and the solid-state diffusion could be the limiting process depending on the lithiation/delithiation states. In addition, the MnO/C anode delivers an energy efficiency of 90% in a Li-ion hybrid capacitor, suggesting a promising and competitive application in the future.

Graphical abstract: Understanding the electrochemical potential and diffusivity of MnO/C nanocomposites at various charge/discharge states

Supplementary files

Article information

Article type
Paper
Submitted
03 Jan 2019
Accepted
25 Feb 2019
First published
27 Feb 2019

J. Mater. Chem. A, 2019,7, 7831-7842

Author version available

Understanding the electrochemical potential and diffusivity of MnO/C nanocomposites at various charge/discharge states

C. Liu, H. Fu, Y. Pei, J. Wu, V. Pisharodi, Y. Hu, G. Gao, R. J. Yang, J. Yang and G. Cao, J. Mater. Chem. A, 2019, 7, 7831 DOI: 10.1039/C9TA00056A

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