Mechanism of the entire overdischarge process and overdischarge-induced internal short circuit in lithium-ion batteries

Abstract

Lithium-ion batteries connected in series are prone to be overdischarged. Overdischarge results in various side effects, such as capacity degradation and internal short circuit (ISCr). However, most of previous research on the overdischarge of a cell was terminated when the cell voltage dropped to 0 V, leaving the further impacts of overdischarge unclear. This paper investigates the entire overdischarge process of large-format lithium-ion batteries by discharging the cell to −100% state of charge (SOC). A significant voltage platform is observed at approximately −12% SOC, and ISCr is detected after the cell is overdischarged when passing the platform. The scanning electron microscopy (SEM) and X-ray diffraction (XRD) results indicate that the overdischarge-induced ISCr is caused by Cu deposition on electrodes, suggesting possible Cu collector dissolution at the voltage platform near −12% SOC. A prognostic/mechanistic model considering ISCr is used to evaluate the resistance of ISCr (RISCr), the value of which decreases sharply at the beginning of ISCr formation. Inducing the ISCr by overdischarge is effective and well controlled without any mechanical deformation or the use of a foreign substance.

Detection of Internal Short Circuit in Lithium Ion Battery Using Model-Based Switching Model Method

“…Therefore, using the assumption [18] that the first parameter This model with ISCr has been verified to mimic the ISCr [17]. Especially, subscript f (fault) is used to distinguish between parameters related to the model with ISCr and parameters of the normal battery model.…”

“…Furthermore, decrease in represents increase in the severity of the ISCr in the Li-ion battery and in the decline of estimated SOCs. Using the self-discharge phenomenon, can be estimated [18]. The coulomb counting method is usually used to calculate true SOCs from the load current, true initial SOC and total capacity [21].…”

“…Furthermore, decrease in R ISC f represents increase in the severity of the ISCr in the Li-ion battery and in the decline of estimated SOCs. Using the self-discharge phenomenon, R ISC f can be estimated [18].…”

“…The ISCr can be detected by using variation of estimated parameters in the equivalent circuit model and the energy balance equation [16], but this method must be verified with other load current profiles to check whether the estimated parameters show similar variation. When the ISCr occurs in the Li-ion battery, the terminal voltage increases once the battery is recharged, but the voltage reaches a stable value [18]; can be calculated using the charging current and the terminal voltage. However, calculation of by this method requires knowledge of the specific charging current that makes the terminal voltage reach the stable value in the battery with ISCr.…”

Detection Method for Soft Internal Short Circuit in Lithium-Ion Battery Pack by Extracting Open Circuit Voltage of Faulted Cell

“…The R ISCr is regarded as a promising fault index for detecting the ISCr because it can describe self-discharge phenomenon caused by the ISCr in the equivalent circuit model with R ISCr [28,29] and represent heat generated by the ISCr [30]. Therefore, the ISCr detection methods, which directly use the R ISCr as the fault index, have been introduced [29,[31][32][33].…”