A multi-technique approach to understanding delithiation damage in LiCoO2 thin films

TL;DR

This study employs multiple advanced techniques to analyze how delithiation causes structural damage in LiCoO2 thin films, revealing different regimes of surface, bulk, and damage processes, and highlighting inhomogeneities.

Contribution

It introduces a comprehensive multi-technique approach to understand delithiation-induced damage in LiCoO2, emphasizing the role of surface and bulk processes and local inhomogeneities.

Findings

Identification of three delithiation regimes: surface, bulk, and damage.

Only some grains are affected, leading to local inhomogeneities.

Chemical delithiation avoids electrolyte issues, aiding in in situ studies.

Abstract

We report on the delithiation of LiCoO2 thin films using oxalic acid (C2H2O4) with the goal of understanding the structural degradation of an insertion oxide associated with Li chemical extraction. Using a multi-technique approach that includes synchrotron radiation x-ray diffraction, scanning electron microscopy, micro Raman spectroscopy, photoelectron spectroscopy and conductive atomic force microscopy we reveal the balance between selective Li extraction and structural damage. We identify three different delithiation regimes, related to surface processes, bulk delithiation and damage generation. We find that only a fraction of the grains is affected by the delithiation process, which may create local inhomogeneities. The chemical route to Li extraction provides additional opportunities to investigate delithiation while avoiding the complications associated with electrolyte breakdown and could simplify in situ measurements.