State of Health Estimation for Lithium-Ion Batteries

Abstract

The state of health (SoH) of lithium-ion batteries and battery packs must be monitored effectively to prevent failure and accidents, and to prolong the useful lifetime of the batteries. Many studies have suggested that temperature and discharge/charge current rate are the primary factors causing battery aging. However, due to the complex and often poorly understood internal dynamics of lithium-ion batteries, no reliable mathematical models to predict the battery SoH are available. In this article, we introduce two SoH prediction models: (1) the decreasing battery V0+ model and (2) the increasing CV charge capacity model. Additionally, we derive a simple thermal model for the cell based on variation of temperature data.