In situ neutron powder diffraction measurements of a commercial lithium-ion battery reveal perturbations to the phase evolution of the Li x C6 electrode caused by overcharge. Above ∼4.5 V the anode is entirely composed of LiC6. During discharge from the post-overcharged state LiC6 persists to the 90% discharge state, compared with its persistence to the 27% discharge state during conventional cycling. At the completely discharged state the post-overcharged anode is a mixture of LiC12, LiC18, and graphite, while the conventionally cycled anode is composed of graphite alone. The phase evolution of a post-overcharged battery during charge also differs relative to conventional cycling, most noticeably until the 9% state of charge.