Fundamentals and Applications of Lithium-ion Batteries in Electric Drive Vehicles
by Jiuchun Jiang, Caiping Zhang
2Performance Modeling of Lithium-ion Batteries
The battery model describes the mathematical relationship between voltage, power, current, state of charge (SOC), temperature, and other factors which impact performance during working. It not only shows the basis of state estimation, performance analysis, scientific evaluation and use, but also works as a bridge from external characteristics to the internal state. So the battery model has been of wide interest to researchers.
2.1 Reaction Mechanism of Lithium-ion Batteries
A lithium-ion battery is a high-energy battery in which Li+ embeds into and escapes from positive and negative materials when charging and discharging. As illustrated in Figure 2.1, from left to right, a battery consists of a cathode current collector, negative electrode active materials, electrolyte, a separator, positive electrode active materials, and an anode current collector. Positive electrode materials of lithium-ion batteries are intercalation compounds of lithium-ion, commonly LiCoO2, LiNiO2, LiMn2O4, LiFePO4 and LiNixCo1-2xMnxO2, and so on. Negative electrode materials are commonly LixC6, TiS2, V2O5, and so on. The electrolyte is an organic solvent in which the lithium salts, such as LiPF6, LiBF4, LiClO4, LiAsF6, and so on, are soluble. The solvents are mainly ethylene carbonate ( EC), propylene carbonate ( PC), dimethyl carbonate ( DMC), chlorine methyl carbonate ( ClMC), and so on. The main role of the separator in a battery is to isolate the positive ...