Study on the Voltage Characteristic of Lithium Ion Battery during Rest Period after Charge

Abstract

Abstract. The open circuit voltage (OCV) of lithium ion battery is a key parameter for hybrid electric vehicle (HEV) to estimate the state-of-charge (SoC). And its instability will lead to big error of SoC estimation and have difficulty in implementing the dynamic control strategy of HEV, especially when the lithium ion battery rests after regenerative braking. According to the theory of electrochemistry, the lithium iron phosphate battery is studied in order to analyze the influence mechanism of lithium ion diffusion on the OCV when it rests after charge. And an OCV model appropriate for the rest period after charge is built by combining experiment with parameter identification method. The result of experiment shows that the OCV model is consistent with the OCV characteristic.