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| Hauptseite > Publikationsdatenbank > Crystallization behavior and electrochemical performance of pure LiFePO4 thin films deposited on aluminum foil by unbalanced radiofrequency (RF)-magnetron sputtering |
| Hauptseite > Publikationsdatenbank > Crystallization behavior and electrochemical performance of pure LiFePO4 thin films deposited on aluminum foil by unbalanced radiofrequency (RF)-magnetron sputtering |
| Abstract | FZJ-2014-00506 |
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2014
Abstract: In literature on sputter deposition of thin film LiFePO4, substrates like stainless steel or substrates coated with titanium or platinum were used almost exclusively. Due to the reasonable temperature stability of these materials, amorphous thin films can be crystallized over a wide temperature range. However, for commercial applications, these substrates are either too expensive or have unfavorable high densities and therefore reduce the specific energy density. An alternative substrate material with a comparable low price and a lower density is aluminum, which is also used in standard Li Ion batteries as current collector. However, because of the low melting point of aluminum the temperature range for the crystallization of as deposited LiFePO4 films is limited to 660 °C. The aim of this work is to characterize the crystallization and electrochemical behavior of unbalanced RF-magnetron sputtered LiFePO4 thin films on aluminum substrates. Moreover, the effect of charging and discharging on the LiFePO4 on the composition and structure is analyzed. Pure LiFePO4 is deposited on 250 µm thick aluminum foils. Due to the unbalanced plasma, the substrates heat up to 100 °C during the deposition process. For crystallization of the LiFePO4 thin films, a subsequent annealing step at temperatures between 300 °C and 500 °C was conducted in Argon atmosphere. The structure and morphology was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) before and after electrochemical measurements in Sawgelok® cells with liquid electrolyte. The electrochemical performance was investigated using cyclic voltammetry and charge/discharge measurements of the LFP thin films.
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