Physical and chemical characterization of LiCoO₂ cathode material extracted from commercial cell phone batteries with low and high states of health

Technological and scientific efforts have been driven in order to clarify the changes in physical, chemical, and mechanical properties of lithium-ion battery components that lead to aging and failures in such batteries. Most of these studies have been carried out in laboratory scale and under accelerated battery aging processes. For a more realistic approach, cell phone batteries with low and high state of health (L and H SOH), discarded by their users were analyzed. LiCoO₂ cathode material (L and H cathodes) showed properties deeply dependent on the battery SOH. Two hexagonal crystalline phases, expanded lattice and atomic disordering, were observed in the L cathode material by X-ray diffractometry and Raman spectroscopy measurements. Distinct infrared absorption profiles were observed for L and H cathode materials in the O-Co-O bending vibration region. Measurements of particle size distributions suggest a progressive fragmentation of LiCoO₂ particles with the battery cycling. Additionally, mechanical deformations in the electrode's winding and in the battery case were observed for the lower SOH battery.