The Potential Regulation of Working Anode for Long‐Term Zero‐Volt Storage at 37 °C in Li‐Ion Batteries

Abstract

The advanced lithium‐ion batteries (LIBs) that can tolerate over‐discharge to 0 V and zero‐volt storage (ZVS) are highly desired for active implantable medical devices and spacecraft. However, ZVS can raise the anode potential and lead to continuous oxidation of the Cu current collectors and SEI degradation, which significantly reduces battery capacity and causes safety issues, especially at 37°C. In this contribution, a stable anti‐fluorite structured compound, Li6CoO4, is proposed as a cathode additive for zero‐volt storage of LIBs. By quantitatively regulating the dosage of Li6CoO4 additives, controllable potential of the working anode under abusive‐discharge conditions has been demonstrated. The addition of Li6CoO4 keeps ZCP (zero‐crossing potential) and the potential of ZVS less than 2.0 V (versus Li/Li+) for LiCoO2|mesocarbon microbead cells at 37°C. The capacity retention ratio (CRR) increases from 69.1% and 35.9% to 98.6% and 90.8% after 10 and 20 days of ZVS, respectively. The dissolution of the Cu and degradation of SEI have been effectively suppressed, while the over‐lithiated cathode exhibits high reversible capacity in working ZVS batteries. The limiting conditions of long‐term ZVS has been explored and a corresponding guide map is designed. When quantitatively regulating ZCP and the potential in ZVS, special attention should be paid to avoid the threshold of Cu dissolution, the rate of SEI degradation as potential rises, the time and potential window for irreversible conversion of the cathode. This contribution designs the most reasonable potential range for ZVS protection at 37°C, and realizes the best CRR record through precise potential regulation for the first time.This article is protected by copyright. All rights reserved