Enhanced electrochemical properties of fluoride-coated LiCoO2 thin films
The electrochemical properties of fluoride-coated lithium cobalt oxide [LiCoO2] thin films were characterized. Aluminum fluoride [AlF3] and lanthanum fluoride [LaF3] coating layers were fabricated on a pristine LiCoO2 thin film by using a spin-coating process. The AlF3- and LaF3-coated films exhibited a higher rate capability, cyclic performance, and stability at high temperature than the pristine film. This indicates that the AlF3 and LaF3 layers effectively protected the surface of the pristine LiCoO2 film from the reactive electrolyte.
Improve the structure and electrochemical performance of LiNi0.6Co0.2Mn0.2O2 cathode material by nano-Al2O3 ultrasonic coating
Abstract The LiNi 0.6 Co 0.2 Mn 0.2 O 2 powder was coated with nano-Al 2 O 3 particles via ultrasonic coating, and its electrochemical performances were improved greatly. The X-ray diffraction, scanning electron microscopy, transmission electron microscope and energy dispersive spectroscopy were employed to research the structure variation, surface appearance and coating status. The results show that the nano-Al 2 O 3 particles are successfully coated and the thickness of coating layer is about 20–25 nm. The XRD test results indicate that appropriate amount of Al 2 O 3 coated is beneficial to form a better layered structure with smaller cation disorder. The charge–discharge results show that LiNi 0.6 Co 0.2 Mn 0.2 O 2 coated with Al 2 O 3 of 1.0 wt.% has initial discharge capacity of 197.1 mA h g −1 , initial coulombic efficiency of 91.2% at 0.2 C over 2.8–4.5 V and capacity retention of 91.0% much more than the pristine one of 82.9.0% after 30 cycles at 1 C. Especially, the rate capability of 1.0 wt.% Al 2 O 3 -coated sample is improved evidently, it shows a high discharge capacity of 153.5 mA h g −1 after 5 cycles under a 10 C rate, whereas the pristine one is only 126.3 mA h g −1 under the same conditions. The electrochemical impedance spectroscopy tests results also show that the impedance of LiNi 0.6 Co 0.2 Mn 0.2 O 2 is significantly reduced by Al 2 O 3 coating during the cycling.
"Flying Triangulation" - a new optical 3D sensor enabling the acquisition of surfaces by freehand motion
In order to obtain complete 3D surface information of an object it is often necessary to acquire many partial 3D views. For this purpose, the sensor has to be moved (e.g. for the acquisition of sculptures or rooms). Further, in many cases a motion of the object relative to the sensor is unintended but inevitable (e.g. for medical applications such as intraoral measurements of teeth). Nearly all existing optical 3D sensors either lack an easy handling or require a standstill during the acquisition of a single partial 3D view, since usually multiple camera shots have to be taken for this purpose. This makes such measurements elaborate or even impossible.