How to Model the Lithium Ion Battery Voltage Curve
The battery voltage curve is a key indicator of the performance and service life of a lithium ion battery. It shows the charge voltage and current levels in the cell that maximize the battery's capacity and power output.
When charging, lithium ions flow from the anode to the cathode through an electrolyte in between the electrodes. The ions then reform at the cathode. When discharging, the ions and electrons flowing from the anode to the cathode release chemical energy stored in the cell in the form of electrical energy.
A lithium ion battery is composed of a non-metallic anode and a graphite or manganese dioxide cathode. These batteries can be recharged and discharged many times without losing their maximum power.
In the first stage of charging a li-ion battery or cell, constant current charge is used to increase the charge voltage until it reaches a level called saturation charge. This phase of charge typically takes two hours or more, depending on the type and manufacturer of the cell.
At this point, the voltage peaks at around 4.2 Volts for consumer orientated lithium cobalt oxide (LCO) cells and batteries, which is the maximum allowable voltage to ensure maximum battery life. Charging beyond this voltage will cause stress to the cell and result in oxidation that reduces battery capacity and service life.
In this study, a novel method based on a neural network model is proposed to model and calculate the battery voltage curves, thus allowing more accurate analysis and modeling of IC peaks and capacities. The resulting results show better performance than the traditional voltage differentiation method.
