Real-Time Analysis of a Single Secondary Particle Using an Electrochemical Modeling

Abstract

Promising electrode active materials such as LiNiMnCoO2, LiNiCoAlO2 and LiFePO4 is made by a secondary particle containing millions of primary particles to improve its conductivity and diffusion. Therefore, design and analysis of the secondary particle are most important things to improve the performance of the active material so some groups are studying the intrinsic characteristics by a single particle measurement technique which cycle a half-cell of a single active material particle and lithium metal. With this method, we can calculate the diffusion coefficient, exchange current densityNevertheless, it is almost impossible to see what happened inside the particle during cycling and it is hard to optimize particle design by this method to meet the required each condition including high power or long cycle life.To overcome this situation, we developed a single particle model which can easily analyze inside of the particle as well as design the particle. To get the reliability of the model, we compared the experimental result by the single particle measurement technique and the simulation result. Using this model, we can estimate the real-time properties including distributions of lithiation, electric potential and overpotential inside the particle and concentration in a liquid phase. Besides, we analyze the secondary particle with change of the particle design (solid volume fraction, primary particle size and secondary particle size)