Atomic-scale insights on grain boundary segregation in a cathode battery material

TL;DR

This study uses advanced microscopy techniques to analyze atomic-scale grain boundary segregation in a lithium-ion battery cathode, revealing impurity and element segregation that affect material performance.

Contribution

It provides detailed atomic-scale insights into grain boundary segregation in LiNi0.5Mn1.5O4, a key cathode material, using transmission electron microscopy and atom probe tomography.

Findings

Segregation of Mn, O, Na observed at grain boundaries.

Depletion of Ni and Li at grain boundaries.

Segregation of O and Mn at dislocations.

Abstract

The grain boundary segregation of the Co-free pristine spinel LiNi0.5Mn1.5O4 cathode material has been studied by transmission electron microscopy and atom probe tomography. The segregation of Mn and the depletion of Ni at grain boundaries was observed by electron energy loss spectroscopy. These observations were also confirmed by atom probe tomography at other grain boundaries, which also revealed segregation of O and depletion of Li at grain boundaries. In addition, both methods revealed the occurrence of grain boundary segregation of Na, which is an impurity. Finally, segregation of O and Mn and a depletion of Li are also observed at dislocations. This observation has the potential to provide further support for the segregation behavior at the grain boundaries of this cathode material. These near-atomic-scale observations provide new insights that can be used to improve the synthesis and efficiency of Li-ion battery materials.