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Characterization of thermally aged AlPO4-coated LiCoO2 thin films.

Jung E, Park YJ - Nanoscale Res Lett (2012)

Bottom Line: The wide and smooth surface of the thin film electrode might provide an opportunity for one to observe surface reactions with an electrolyte.Based on secondary ion mass spectrometry analysis and scanning electron microscopy images of the surface, it was confirmed that the coating layer was successfully protected from the reactive electrolyte during storage at 90°C.In contrast, the surface of the pristine sample was severely damaged after storage.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Advanced Materials Engineering, Kyonggi University, Suwon, Gyeonggi-do, 443-760, Republic of Korea. yjpark2006@kyonggi.ac.kr.

ABSTRACT
The electrochemical properties and stability during storage of pristine and AlPO4-coated LiCoO2 thin films were characterized. The wide and smooth surface of the thin film electrode might provide an opportunity for one to observe surface reactions with an electrolyte. The rate capability and cyclic performance of the LiCoO2 thin film were enhanced by AlPO4 surface coating. Based on secondary ion mass spectrometry analysis and scanning electron microscopy images of the surface, it was confirmed that the coating layer was successfully protected from the reactive electrolyte during storage at 90°C. In contrast, the surface of the pristine sample was severely damaged after storage.

No MeSH data available.


SEM images of (a) Pristine and (b) AlPO4-coated LiCoO2 thin films. The EDS peak of the coating layer is shown on the right.
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Figure 1: SEM images of (a) Pristine and (b) AlPO4-coated LiCoO2 thin films. The EDS peak of the coating layer is shown on the right.

Mentions: The cross-sectional image of the pristine and AlPO4-coated LiCoO2 thin films is presented in Figure 1. The thickness of the LiCoO2 film was approximately 4 μm. The coating layer of the coated film was not clearly observed in the scanning electron microscopy [SEM] image, which may have been due to the thin coating thickness. However, the Al and P elements were confirmed using energy dispersive spectroscopy [EDS] analysis, which implied the existence of an AlPO4 coating layer. To confirm the coating effect on the electrochemical property, the discharge capacity and cyclic performance were measured at current densities of 0.2, 0.4, and 0.6 mA·cm-2 in a voltage range of 4.25 to 3.0 V. The current densities could be converted to approximately 1-C, 2-C, and 3-C rates, considering that the average capacity of the LiCoO2 thin film is approximately 50 μAh·cm-2·μm-1. The film electrodes do not contain conducting agents, such as carbon, and they are vulnerable at the rate capability. As shown in Figure 2a, the initial discharge capacities of the pristine and AlPO4-coated samples were similar. However, with an increase in the current density, the coated film showed a superior discharge capacity and cyclic performance. Figures 2b and 2c present the voltage profiles of the pristine and coated samples at current densities of 0.2, 0.4, and 0.6 mA·cm-2 as a function of the capacity (the first cycle of Figure 2a at each current density). The discharge capacity of the pristine film dropped rapidly at a high current density. However, the coated film showed much improved capacity retention under the identical condition.


Characterization of thermally aged AlPO4-coated LiCoO2 thin films.

Jung E, Park YJ - Nanoscale Res Lett (2012)

SEM images of (a) Pristine and (b) AlPO4-coated LiCoO2 thin films. The EDS peak of the coating layer is shown on the right.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3275528&req=5

Figure 1: SEM images of (a) Pristine and (b) AlPO4-coated LiCoO2 thin films. The EDS peak of the coating layer is shown on the right.
Mentions: The cross-sectional image of the pristine and AlPO4-coated LiCoO2 thin films is presented in Figure 1. The thickness of the LiCoO2 film was approximately 4 μm. The coating layer of the coated film was not clearly observed in the scanning electron microscopy [SEM] image, which may have been due to the thin coating thickness. However, the Al and P elements were confirmed using energy dispersive spectroscopy [EDS] analysis, which implied the existence of an AlPO4 coating layer. To confirm the coating effect on the electrochemical property, the discharge capacity and cyclic performance were measured at current densities of 0.2, 0.4, and 0.6 mA·cm-2 in a voltage range of 4.25 to 3.0 V. The current densities could be converted to approximately 1-C, 2-C, and 3-C rates, considering that the average capacity of the LiCoO2 thin film is approximately 50 μAh·cm-2·μm-1. The film electrodes do not contain conducting agents, such as carbon, and they are vulnerable at the rate capability. As shown in Figure 2a, the initial discharge capacities of the pristine and AlPO4-coated samples were similar. However, with an increase in the current density, the coated film showed a superior discharge capacity and cyclic performance. Figures 2b and 2c present the voltage profiles of the pristine and coated samples at current densities of 0.2, 0.4, and 0.6 mA·cm-2 as a function of the capacity (the first cycle of Figure 2a at each current density). The discharge capacity of the pristine film dropped rapidly at a high current density. However, the coated film showed much improved capacity retention under the identical condition.

Bottom Line: The wide and smooth surface of the thin film electrode might provide an opportunity for one to observe surface reactions with an electrolyte.Based on secondary ion mass spectrometry analysis and scanning electron microscopy images of the surface, it was confirmed that the coating layer was successfully protected from the reactive electrolyte during storage at 90°C.In contrast, the surface of the pristine sample was severely damaged after storage.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Advanced Materials Engineering, Kyonggi University, Suwon, Gyeonggi-do, 443-760, Republic of Korea. yjpark2006@kyonggi.ac.kr.

ABSTRACT
The electrochemical properties and stability during storage of pristine and AlPO4-coated LiCoO2 thin films were characterized. The wide and smooth surface of the thin film electrode might provide an opportunity for one to observe surface reactions with an electrolyte. The rate capability and cyclic performance of the LiCoO2 thin film were enhanced by AlPO4 surface coating. Based on secondary ion mass spectrometry analysis and scanning electron microscopy images of the surface, it was confirmed that the coating layer was successfully protected from the reactive electrolyte during storage at 90°C. In contrast, the surface of the pristine sample was severely damaged after storage.

No MeSH data available.