A Rapid Depolarization Charge and Discharge Technique for Lithium Ion Batteries

Abstract

There is a serious diffusion-polarization effect in the working process of lithium-ion batteries, resulting in a large rebound of battery voltage after charge/discharge. The measurement of the open circuit voltage (OCV) of the battery was interfered by the existence of this polarization, while accuracy of battery state of charge estimating based on open circuit voltage and state of charge (SoC) curve is reduced. At the same time, measurement of AC impedance spectrum was interfered by the fluctuating voltage. In this work battery was rapidly depolarized through pulse charge-discharge in discharging procedure. Compared with the standard depolarization method by reducing the discharge rate (0.05C), the discharge test time was reduced by 72.5% and polarization effect was weakened at low SoC. There was no significant difference in results for this charging technology compared with EIS curve tested after conventional charging and reduced test time by 42%.