Self-weakening in lithiated graphene electrodes

We present a molecular dynamics study of the fracture mechanisms of lithiated graphene. Our modeling results reveal that lithium diffusion toward the crack tip is both energetically and kinetically favored owing to the crack-tip stress gradient. The stress-driven lithium diffusion results in lithium aggregation around the crack tip, chemically weakening the crack-tip bond and at the same time causing stress relaxation. Our simulations show that the chemical weakening effect is the dominant factor, which manifests a self-weakening mechanism in lithiated graphene. The atomistic understanding of the degradation mechanism provides guidance for the lifetime extension in the design of graphene-based electrodes.