Abstract
We report on the potential and temperature dependences of the differential intercalation capacitance, Cdif, and the chemical diffusion coefficient, D, during Li intercalation into a graphite anode by a combined application of slow-scan rate cyclic voltammetry (SSCV) and the potentiostatic intermittent titration technique (PITT). Drastically different behavior was observed within the short-time ranges of the PITT response measured for a two-phase coexistence domain and a solid solution of phases 4 and 3. Electroanalytical evidence for small droplet formation (nucleation) of a new phase in the bulk of the old one was found for the former domain, showing good correlation with in situ XRD studies. SSCV data obtained in the 25-80 °C temperature range were in excellent agreement with the published temperature-concentration phase diagrams built on the basis of detailed XRD characterizations. The simultaneous appearance of maxima on Cdif versus E plots and minima on the related log D versus E plots in the two-phase domains was rationalized in terms of a lattice gas model with single site energy, and highly attractive interactions between the intercalated guest atoms. The electroanalytical behavior of graphite within the solid-solution domain (a mixture of phases 4 and 3) was interpreted semi-quantitatively on the basis of a model that took into account the presence of two sub-lattices of different energy (a model of "energetic heterogeneity") for Li accommodation, and attractive interactions between the guest atoms on each sub-lattice, or, alternatively, due to in-plane order-disorder transitions because of short-range repulsive interactions between the intercalated guest species.
Original language | English |
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Pages (from-to) | 187-203 |
Number of pages | 17 |
Journal | Journal of Electroanalytical Chemistry |
Volume | 562 |
Issue number | 2 |
DOIs | |
State | Published - 1 Feb 2004 |
Bibliographical note
Funding Information:This work has been supported by the Grant Agency of Academy of Sciences of the Czech Republic, N IAA 1010207. We are grateful to Dr. E. Vakarin for helpful discussions of the results related to application of surface heterogeneity model to Li intercalation in the solid-solution domain of Li x C 6 .
Funding
This work has been supported by the Grant Agency of Academy of Sciences of the Czech Republic, N IAA 1010207. We are grateful to Dr. E. Vakarin for helpful discussions of the results related to application of surface heterogeneity model to Li intercalation in the solid-solution domain of Li x C 6 .
Funders | Funder number |
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Akademie Věd České Republiky | N IAA 1010207 |
Keywords
- Diffusion coefficient
- Elevated temperatures
- First-order phase transition
- Lattice gas model
- Li-ion cell
- LiC
- PITT