Mechanism of lithium plating and stripping in lithium-ion batteries induced by overhang failure defects

Manufacturing defects in the anode can induce non-uniform lithium plating, which significantly impacts the safety and cycle life of lithium-ion batteries. This study investigates the lithium plating mechanism induced by overhang failure defects, characterized by an anode that is 7 mm shorter than the cathode. The lithium deposition in the defect region is inevitable even during cycles without fast or low-temperature charging. Additionally, a delay effect of the lithium plating and stripping process in the defect region is discovered. Specifically, lithium plating occurs during resting and partial discharging stages, while lithium stripping occurs during resting and the subsequent charging stages. Lithium plating is induced by the gradient in solid-phase lithium-ion concentration between the defect region and the normal region during charging. The cessation of lithium plating during cycling is determined by the reduction of solid-phase lithium-ion concentration in the defect region's cathode.