Analysis of fading characteristics of a lithium ion battery based on an integration model

摘要

We utilize an integration model of capacity degradation in electrochemical kinetics to analyze the fading characteristics of a lithium-ion battery. On the basis of the assumed parameters of the parasitic reaction, the characteristic of the lithium-ion battery are simulated before and after 100 charge-discharge cycles with the Comsol Multiphysics 4.3 software. After 100 cycles, the curves of voltage vs. state of charge under charge or discharge display a descending trend. The charge and discharge capacities decrease 8.0% and 3.85% at 1 C constant current when the cut-off voltages are set at 4.3 V and 2.8 V, respectively. In addition, the decreased capacity is related significantly to the applied current rate. By analysis, the decreased capacity due to the consumed Li* concentration by the solid-electrolyte interphase reaction is only about 0.05%, showing an extremely slight influence. Thus, the elevated film resistance plays a crucial role in decrement of the capacity. The results also display that state of charge should be set at a lower value, at least under 57%, to protect the battery from fading when it is stored for a long time.