Quantification of the Deep Discharge Induced Asymmetric Copper Deposition in Lithium‐Ion Cells by Operando Synchrotron X‐Ray Tomography

Abstract

Lithium‐ion cells connected in series are prone to an electrical safety risk called overdischarge. This paper presents a comprehensive investigation of the overdischarge phenomenon in lithium‐ion cells using operando nondestructive imaging. The study focuses on understanding the behavior of copper dissolution and deposition during overdischarge, which can lead to irreversible capacity loss and internal short‐circuits. By utilizing synchrotron X‐ray computed tomography (SXCT), the concentration of dissolved and deposited copper per surface area is quantified as a function of depth of discharge, confirming previous findings. The results also highlight for the first time a nonuniform distribution pattern for copper deposition on the cathode. This research provides insights for safer battery cell design.

Efficient Workflows for Detecting Li Depositions in Lithium-Ion Batteries

“…Discharge below the end-of-discharge voltage can result in Cu dissolution from the anode current collecting foil. 163,164,[199][200][201][202][203] Cu dissolution to Cu 2+ or Cu + gets thermodynamically allowed when the anode potential increases above 3.38 V or 3.56 V vs Li/Li + , respectively. 164 Furthermore, Flügel et al showed for seven types of commercial cells, that the additional discharge from the end-ofdischarge voltage to 0 V leads only to minor decreases of cell energy corresponding to negative SOCs of −3% to −9%.…”