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QQ4.08 - A Study on Li-Ion Intercalation and Phase Transition Characteristics in Cathode of Li-Ion Battery 
April 23, 2014   11:30am - 11:45am

Li-ion batteries are widely used for power source of portable devices and electric vehicles due to its high energy density. Many researchers study Li-ion diffusion in a Li-ion battery including cathode, anode and electrolyte. Because the Li-ion diffusion directly affects electron flows. Diffusion of Li-ion is faster in electrolyte than each electrode. The reason for these phenomena is Li-ion diffuses freely in electrolyte but hard to diffuse in cathode because intercalation sites are limited. Li-ion stagnation which induces disturbance of Li-ion intercalation occurs at an interface between electrode and electrolyte since the diffusivity of Li-ion is different. The Li-ion intercalation and diffusion in the electrodes are primary depending on material properties of electrode. Moreover, other important factors such as phase transition and Li-ion distribution characteristics on affecting Li-ion intercalation have been proposed. The specific characteristics are different in each electrode. Generally, carbon is suggested for anode material but many transient metals are considered as candidates of cathode. Numerical study has been performed to analyze Li-ion intercalation in cathodes and evaluate performance of the Li-ion batteries with various transient metals. The both of phase transitions and Li-ion distributions are considered in the computational model. The Li-ion distribution behaviors in cathode materials can be classified as continuous and discrete types. In the case of cathodes reside in the continuous distribution, the Li-ion concentration is gradual increasing or decreasing as Li-ion is intercalated or extracted. And ratio of each phase can be expressed as function of Li-ion concentration and changes smoothly. On the other hand, Li-ion concentration is also changed in the discrete case. The Li-ion concentration only exists at specific values to ensure that the structure is in the stable state. Li-ion concentration still exists at specific values and only ratio of each phase is changed when giving different Li-ion concentration. In the cathode, the specific Li-ion concentration corresponds to the phase, Li-ion concentration jumps between the stable values. Here, we construct phase field model of the Li-ion diffusion incorporate phase transition. The computational method provides a detailed understanding on the process of Li-ion intercalation and enhances the cathode structure for high capacity battery..

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Panel Discussion - Different Approaches to Commercializing Materials Research
Business Challenges to Starting a Materials-Based Company
Fred Kavli Distinguished Lectureship in Nanoscience
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