| Summary: | 碩士 === 輔仁大學 === 化學系 === 106 === In this study, the tungsten modified LiNi0.8Co0.2O2 (W-LNCO) cathode materials had been successfully synthesized via a solid-state mixing method. Under the scanning electron microscope observations, these images of materials show the synthesized precursor particles with spherical morphologies and the particle sizes of about 8~15 μm. All the powders were confirmed to have a well-defined α-NaFeO2-type structure (space group, R-3m) by the XRD tests. Electrochemical testing results show the discharge capacity of 0.5%W-LNCO and 1.0%W-LNCO are 186.5 mAh/g and 173.2 mAh/g, respectively. The corresponding values for LNCO are 189.2 mAh/g. 0.5%W-LNCO returned values for rate capability and cycle-life that were superior to those of LNCO and 1.0%W-LNCO. Electrochemical impedance spectroscopy (EIS) analysis showed that the tungsten modified LNCO cathode material suppressed the reactions of electrolytes with the material and inhibited increases in resistance. In addition, tungsten modified LNCO cathode material could also accelerate the Li+ ion diffusion based on results of potentiostatic intermittent titration technique (PITT). Finally, the 0.5%W-LNCO cathode material showed higher exothermic temperature and smaller level of exothermic heat than the pristine LNCO by the differential scanning calorimetry (DSC) analysis.
|
|---|
