Overdischarge process of lithium-ion batteries for the recovery of low-damaged cathodes.

Two overdischarge methods for lithium-ion batteries were compared. The contamination and degradation of cathode surfaces were analyzed. The suitability for multi-cell application was examined. [Display omitted] • The paper is related to the recycling of spent batteries. • An overdischarge process as a step of battery recycling was investigated. • Two methods were investigated to address the safety during cell shredding and the recovery possibility of clean material. • A better method was implemented using 10-cells connected in series. • The method provides a simple overdischarge process without a high-specification discharger. An overdischarge process as a step of battery recycling was investigated using a spent battery. The procedure aims to obtain clean materials while ensuring safety during the disassembly of battery cells. Two overdischarge methods were compared. One method (Method A) overdischarged the DOD to 120 %, reaching −0.431 V. The other method (Method B) was to overdischarged the DOD to 0 V and then maintain the voltage for a day. The cleanness and the structure of the cathodes were analyzed by photographs, SEM, BET, ICP, XPS, and XRD. Sample 1 (S1), overdischarged by the Method A, was contaminated by Cu. In contrast, Sample 2 (S2), overdischarged by the Method B, was contaminant-free. A relatively ordered structure was also confirmed. Method B was implemented using 10-cells connected in series. As soon as the module began to discharge, the voltage of all cells was simultaneously reduced. While the module voltage was held at 0 V, the maximum and minimum cell voltages were 0.064 and 0.033 V, respectively, indicating cell balancing was maintained. Therefore, Method B provides a simple overdischarge process for a battery module or pack without a high-specification discharger. [ABSTRACT FROM AUTHOR]