Year: 2025
Type: article
Abstract: Determining the solid diffusion coefficient of lithium in graphite anode active materials for lithium-ion batteries is challenging due to the complex intercalation dynamics, the structural complexity, particle size/shape distribution, and the superposition of liquid electrolyte transport processes in the pores of an electrode. To minimize these influences, we examined the lithiation of highly oriented pyrolytic graphite (HOPG) disk electrodes, with the basal planes stacked normal to the disk thickness (0.5 mm). At first, the radially progressing lithiation of the HOPG disks was followed in situ by top-view optical monitoring of the golden LiC6 phase. However, post-mortem analysis of split HOPG disks revealed that HOPG crystal surface imperfections lead to the artefact that the apparent LiC6 phase progression determined from top-view images does not correspond to that in the bulk of the disks. Thus, the LiC6 phase front position can only be quantified through post-mortem analysis of split HOPG disks. The intercalation time and temperature dependence of the LiC6 phase progression can be reasonably well described by a Fickian diffusion model in cylindrical geometry, yielding an apparent diffusion coefficient of the LiC6 phase front of D 0 = 0.6–1.0 × 10−13 m2 s−1 at 25 °C, with an activation energy of E a = 35.4–39.0 kJ mol−1 (between 10–55 °C).
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $1,950
OpenAlex ID: W4409497262