Facilitating the systematic nanoscale study of battery materials by atom probe tomography through in-situ metal coating

TL;DR

This paper introduces a simple, cost-effective in-situ Cr-coating method for atom probe tomography that preserves lithium-ion battery materials during analysis, enabling more accurate nanoscale microstructural studies.

Contribution

The study demonstrates that in-situ Cr-coating on APT specimens prevents delithiation, improves data quality, and allows detailed analysis of battery cathode microstructures.

Findings

Cr-coating significantly reduces specimen failure during APT analysis.

Revealed substantial cation fluctuations and LiMnO presence in NMC811.

Method is simple, cost-effective, and enhances systematic battery material studies.

Abstract

Through its capability for 3D mapping of Li at the nanoscale, atom probe tomography (APT) is poised to play a key role in understanding the microstructural degradation of lithium-ion batteries (LIB) during successive charge and discharge cycles. However, APT application to materials for LIB is plagued by the field induced delithiation (deintercalation) of Li-ions during the analysis itself that prevents the precise assessment of the Li distribution. Here, we showcase how a thin Cr-coating, in-situ formed on APT specimens of NMC811 in the focused-ion beam (FIB), preserves the sample's integrity and circumvent this deleterious delithiation. Cr-coated specimens demonstrated remarkable improvements in data quality and virtually eliminated premature specimen failures, allowing for more precise measurements via. improved statistics. Through improved data analysis, we reveal substantial cation fluctuations in commercial grade NMC811, including complete grains of LiMnO. The current methodology stands out for its simplicity and cost-effectiveness and is a viable approach to prepare battery cathodes and anodes for systematic APT studies.