This paper presents in situ characterization of lithium-ion diffusion at nano- to micro-meter scales in a Li-rich layered oxide thin film cathode under external bias by using Electrochemical Strain Microscopy (ESM) and Atomic Force Microscopy (AFM) techniques. The local variations of the diffusion coefficient are calculated and visualized from the ESM images. The results indicate that the Li-ion movement is closely correlated with the changes in the surface topography when the Li-rich cathode is subjected to an external bias. Furthermore, bias-induced Li-ion redistribution is partially reversible. Topography evolution due to Li-ion diffusion and relaxation behaviour are observed. The results from this in situ study provide the insight into the Li-ion diffusion mechanism in the cathode material and pave the way for studying the details of the diffusion-related phenomenon in Li-ion battery materials.
This paper presents the results of in situ characterization of grain boundary effects on Li-ion diffusion in Li1.2Co0.13Ni0.13Mn0.54O2 thin film cathode by using various Scanning Probe Microscopy (SPM) techniques.
This paper presents the in situ mapping of temperature-dependent lithium-ion diffusion at the nanometer level in thin film LiCoNiMnO cathode using electrochemical strain microscopy. The thin-film LiCoNiMnO cathode exhibits higher lithium-ion diffusivities with increasing temperature, which explains the higher capacity observed in the lithium-ion batteries with a Li-rich cathode at elevated temperature. In addition, the activation energy for lithium-ion diffusion can be extracted in an Arrhenius-type plot at the level of grain structure with the assumption that the ionic movement is diffusion controlled. Compared with the grain interiors, the grain boundaries show relatively lower activation energy; hence, it is the preferred diffusion path for lithium ions. This study has bridged the gap between atomistic calculations and traditional macroscopic experiments, showing direct evidence as well as mechanisms for ionic diffusion for Li-rich cathode material.
Purpose: To develop a novel conditionally replicative adenovirus vector that targets telomerase-positive cancer cells.Experimental Design: A telomerase gene-derived promoter was used to control the expression of the E1a gene so that the E1a gene is only expressed in telomerase-positive tumor cells. In addition, a reporter gene was also engineered into the vector so that its infection and replication can be monitored easily. Conclusions: The telomerase-targeted adenovirus vector has significant potential as an oncolytic virus as well as a tumor-specific therapeutic gene delivery vehicle.
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