화학공학소재연구정보센터
Journal of the Electrochemical Society, Vol.166, No.12, A2518-A2522, 2019
Particle-Scale Path-Dependent Behavior of LixNi0.5Mn1.5O4 Electrode in Li-Ion Batteries: Part II. Mathematical Modeling
A mathematical model was developed to study the voltage behavior of LixNi0.5Mn1.5O4(LNMO) electrode at particle scale. The phase transition process of Li-1 -> Li-0.5 -> Li-1 in spinel LNMO was modeled by Avrami equation, which was incorporated into lithium transport process in the particle. By simulating the charge and discharge process, numerical results indicated that phase distributions in the LNMO particle are different between charge and discharge at the same SOC condition, which can lead to different capacity utilization in practical battery operation. Results of average phase fractions also qualitatively demonstrated the existence of path dependent behavior of phase transformation inside LNMO electrode, which can be attributed to the competition between diffusion and phase transformation. The path-dependent behavior at different SOC conditions were then studied. Results show that longer phase change time can result in more capacity utilization. The relaxation impact was investigated at last. Numerical results showed that the path-dependence behavior can be reduced by long relaxation, and this is because phase transformation reactions take place during the relaxation period and eventually can reduce the path-dependence effect. (C) 2019 The Electrochemical Society.