Anomalous Behavior During Low Rate Discharge of Li/CFX Cells. Issue 6 (1st June 2022)

• Record Type: Journal Article
• Authors: Seong, Hui Li; Ruiz, John Paul; Jones, John-Paul; Pasalic, Jasmina; Billings, Keith; West, William; Bugga, Ratnakumar; Crowther, Owen; Destephen, Mario; Brandon, Erik J.
• Is Part Of: Journal of the Electrochemical Society. Volume 169:Issue 6(2022)
• Publication Date: 2022-06-01
• Subjects: Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/1945-7111/ac74e1
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : Lithium-carbon monofluoride (Li/CFx ) D-sized battery cells discharged at very low rates (C/1800) were found to deliver inconsistent capacities. These effects were found to be absent as the discharge rate was increased to C/600. Destructive physical analysis of the cells discharged at C/1800 confirmed the effects of corrosion, manifesting as preferential utilization of the Li anode around the copper current collector, discoloration of the remaining excess Li, and more crucially loss of adhesion to the copper current collector, resulting in a premature completion of discharge. This anomalous behavior may be attributed to the competing corrosion reaction at the Li anode during discharge, whereby Li + is lost to the electrolyte at a rate that is similar to the competing current-producing charge transfer process. At higher rates, this corrosion process is masked by the more significant discharge current generated by the full cell, which occurs at a much higher rate. The inconsistent capacity delivery may relate to the uneven breakdown of the surface film at these very low rates, where the current density is very low. Experimental data from both D-sized and three-electrode cells describing this effect are presented, as well as possible remedies for cells where very low discharge rates are desired.