Measurement of concentration profile during charging of Li battery anode materials in LiClO4-PC electrolyte

• Published in: Electrochimica acta Vol. 53; no. 1; pp. 218 - 223
• Main Authors: NISHIKAWA, K, FUKUNAKA, Y, SAKKA, T, OGATA, Y. H, SELMAN, J. R
• Format: Conference Proceeding Journal Article
• Language: English
• Published: Oxford Elsevier 20.11.2007
• Subjects: Applied sciences; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Exact sciences and technology; Scanning electron microscopy; Anode; Organic carbonate; Tin alloy; Lithium Perchlorates; Secondary cell; Concentration profile; Electrode material; X ray diffraction; Surface structure; Lithium battery; Ni-Sn alloy; Incubation period; Morphology; Li metal; Electrodeposition; Holographic interferometry; Electrochemical reaction; Nickel alloy; Binary alloy; Concentration distribution
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2007.06.034

Li metal was galvanostatically electrodeposited on a horizontally positioned, downward-facing Li metal cathode in 0.5M LiClO4- electrolyte. The refractive index profile corresponding to the transient Li+ ion concentration profile formed in the electrolyte solution upon applying a current step was measured in-situ by holographic interferometry. The configuration of the electrolytic cell was such that mass transfer was governed only by transient diffusion and migration, in the absence of convection. Between the moment of closing the current circuit and the time at which the interference fringes started to shift, an incubation period was observed. Such an incubation period had earlier been observed in lithium electrodeposition at a vertical planar Li metal cathode. The incubation period for the horizontal Li cathode was roughly half that for a vertical one. To study the effect of the electrode material on the incubation period, interferometry measurements were also made at an electrodeposited Ni-Sn alloy electrode. The concentration profile formed near the Ni-Sn alloy electrode during lithiation (alloying or intercalation of Li+ into the electrode) agrees well with predictions made by means of the one-dimensional diffusion equation. Only very short incubation period was detected, but the magnitude was negligibly smaller than that of Li metal electrodeposition. The incubation period therefore appears to be characteristic for Li metal electrode only.