Passivation and corrosion of Al current collectors in lithium-ion batteries

Abstract

State-of-the-art lithium-ion batteries inevitably suffer from electrode corrosion over long-term operation, such as corrosion of Al current collectors. However, the understanding of Al corrosion and its impacts on the battery performances have not been evaluated in detail. The passivation, its breakdown, and corrosion of the Al resulted in the deterioration of the solid/solid interface and electrode integrity. Additionally, localized diffusion of F−/Al3+ brought the irreversible current detrimental to the Coulomb efficiency (1.14% loss). Eventually, the behavior led to extensive capacity damage (>20%) to battery performance until lifespan. During the battery cycling, the passivation layer greater than 20 nm was generated near the median voltage. When the charging voltage rose, the passivation layer was squeezed and deformed by the newly generated Al-F-O particles, resulting in stress corrosion cracks. The passivation layer peeled off, and the nano-passivation layer material was re-generated as the voltage continued to rise. The above results were repeated, and the Al matrix was continuously consumed. The passivity breakdown with localized corrosion was derived from ethylene carbonate adsorption, which was highly correlated to the charge voltages, especially at 4.4 V and 4.8 V. The results will serve as a benchmark for electrode corrosion of other advanced energy storage materials, which is crucial for electrode engineering and performance modulation using interfacial design.