Localized degradation influences the separation of cathode active materials from aluminum foil by direct electrical pulsed discharge

Abstract

The impact of cathode sheet degradation on the separation of cathode active materials (CAMs) from the aluminum foil of spent lithium-ion battery (LiB) electrodes using the electric pulse method was investigated. We examined the degradation factors from the usage history and post-disposal storage conditions to elucidate the mechanisms affecting recycling performance. Cathode sheets with different mileage histories were evaluated for uniform degradation effects, whereas additional storage conditions, including ambient and high-humidity environments, were analyzed for localized degradation behavior. The findings indicate that uniform degradation had a minimal impact on separation efficiency, whereas localized degradation, especially under high-humidity conditions, significantly impaired separation due to the formation of spot-like deposits that increased interfacial resistance and promoted pulverization rather than delamination. Chemical analyses revealed that LiPF₆ decomposition, an electrolyte component, is the primary pathway for degradation under ambient storage, leading to HF acid formation, accelerating corrosion and deposit formation on the cathode surface. Samples stored at low temperatures (4 °C) exhibited reduced surface degradation and maintained an effective separation performance. These findings show that reducing moisture exposure and maintaining low temperatures are crucial for effective separation during recycling processes using electrical pulsed discharges.