Deep understanding of LiCoO2 electrode degradation for optimized recycling strategies

Abstract

Empowered by a synergistic combination approach of Scanning Transmission X-ray Microscopy (STXM) imaging and X-ray Absorption Near Edge Structure (XANES) spectroscopy, a quantitative analysis on the composition and spatial distribution of the cathode in a failed 18650 LiCoO2 (LCO) battery was conducted. Distinct compositional differences between the central and peripheral cathode regions in the failed LCO battery were discerned by utilizing bulk XANES in Total Electron Yield (TEY) and Fluorescence Yield (FY) modes. The central region shows more severe degradation in terms of LCO reduction and excess cathode-electrolyte interface (CEI) buildup. Meanwhile, the STXM technique precisely imaged a specific region of interest in the center of the cathode, covering C, O, and F K-edges, and Co L2,3-edge, to deeply investigate the degradation. Quantitative chemical mapping with spatially resolved XANES spectroscopy, facilitate an in-depth understating of the interfacial reactions on battery electrodes and battery failure fundamentals.