Identification of dopant site and its effect on electrochemical activity in Mn-doped lithium titanate

Editors' Suggestion

Identification of dopant site and its effect on electrochemical activity in Mn-doped lithium titanate

Harishchandra Singh, Mehmet Topsakal, Klaus Attenkofer, Tamar Wolf, Michal Leskes, Yandong Duan, Feng Wang, John Vinson, Deyu Lu, and Anatoly I. Frenkel

Phys. Rev. Materials 2, 125403 – Published 20 December 2018

Abstract

Doped metal oxide materials are commonly used for applications in energy storage and conversion, such as batteries and solid oxide fuel cells. The knowledge of the electronic properties of dopants and their local environment is essential for understanding the effects of doping on the electrochemical properties. Using a combination of x-ray absorption near-edge structure spectroscopy (XANES) experiment and theoretical modeling we demonstrate that in the dilute ( $1 at . %$ ) Mn-doped lithium titanate ( $L i_{4 / 3} T i_{5 / 3} O_{4}$ , or LTO) the dopant $M n^{2 +}$ ions reside on tetrahedral ( $8 a$ ) sites. First-principles Mn K-edge XANES calculations revealed the spectral signature of the tetrahedrally coordinated Mn as a sharp peak in the middle of the absorption edge rise, caused by the $1 s \to 4 p$ transition, and it is important to include the effective electron-core hole Coulomb interaction in order to calculate the intensity of this peak accurately. This dopant location can explain the impedance of Li migration through the LTO lattice during the charge-discharge process, and, as a result, the observed remarkable $20 %$ decrease in electrochemical capacity of the $1 %$ Mn-doped LTO compared to pristine LTO.

Received 24 September 2018
Corrected 13 March 2019

DOI:https://doi.org/10.1103/PhysRevMaterials.2.125403

Physics Subject Headings (PhySH)

Dopants Electrochemical properties Electronic structure

X-ray absorption near-edge spectroscopy

Condensed Matter, Materials & Applied Physics

Corrections

13 March 2019

Correction: The fourth sentence of the abstract contained a misspelled word and has been corrected.

Authors & Affiliations

Harishchandra Singh¹, Mehmet Topsakal², Klaus Attenkofer³, Tamar Wolf⁴, Michal Leskes⁴, Yandong Duan⁵, Feng Wang⁵, John Vinson⁶, Deyu Lu^2,*, and Anatoly I. Frenkel^1,7,*

¹Department of Materials Science and Chemical Engineering, Stony Brook University, Stony Brook, New York 11794, USA
²Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, USA
³National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
⁴Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel
⁵Sustainable Energy Technologies Department, Brookhaven National Laboratory, Upton, New York 11973, USA
⁶Materials Measurement Science Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
⁷Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973, USA