Lithiated MnO2 Phases as Cathodes for 3 V Li and Li‐Ion Cells
| Autor: | G. Pistoia, A. Antonini |
|---|---|
| Rok vydání: | 1997 |
| Předmět: |
Renewable Energy
Sustainability and the Environment Chemistry Analytical chemistry Electrolyte Condensed Matter Physics Electrochemistry Redox Cathode Surfaces Coatings and Films Electronic Optical and Magnetic Materials Ion law.invention Rutile law X-ray crystallography Materials Chemistry Electrochemical potential |
| Zdroj: | Journal of The Electrochemical Society. 144:1553-1559 |
| ISSN: | 1945-7111 0013-4651 |
| DOI: | 10.1149/1.1837640 |
| Popis: | Some polymorphs of MnO 2 , i.e., α-, β-, γ-MnO 2 (the latter in the form of two electrochemical MnO 2 and a chemical MnO 2 ), and ramsdellite (R-MnO 2 ), have been submitted to electrochemical potential spectroscopy (EPS) tests. This quasi-equilibrium technique affords a better deconvolution of the various redox steps, thus giving more information with respect to previous tests based on cyclic voltammetries. The electrochemical behavior has been correlated to the type of channels present in the structures and the rutile content of the polymorphs. R-MnO 2 is the form showing the highest reversibility (55% up to 3.4 V). EPS tests were also applied to thermally lithiated α-, γ-, and R-MnO 2 . The higher charge/discharge efficiencies of these forms (up to 87%) are related to the structure stabilization induced by spinel-like domains in the lithiated pristine frameworks. A simple in situ lithiation technique was applied to a cell having Li -0.3 R-MnO 2 as a cathode. By interposing a Li sheet between cathode and current collector, Li was gradually inserted in the cathode upon electrolyte addition, so to form Li -1 R-MnO 2 . Li cells with Li x R-MnO 2 (x ∼0.3 or ∼1) show an excellent behavior especially when a galvanostatic-potentiostatic charging regime is applied. Stable capacities of 0.15 Ah/g may be reached, this producing specific energies above 400 Wh/kg, a value which compares fairly well with that of a 4 V, LiMn 2 O 4 -based cell. The in situ full lithiation of a Li -0.3 R-MnO 2 cathode permits fabrication of 3 V Li-ion cells with this efficient material |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|