  We report on the origin of the surface structural disordering in graphite
anodes induced by lithium intercalation and deintercalation processes. Average
Raman spectra of graphitic anodes reveal that cycling at potentials that
correspond to low lithium concentrations in LixC (0 \leq x < 0.16) is
responsible for most of the structural damage observed at the graphite surface.
The extent of surface structural disorder in graphite is significantly reduced
for the anodes that were cycled at potentials where stage-1 and stage-2
compounds (x > 0.33) are present. Electrochemical impedance spectra show larger
interfacial impedance for the electrodes that were fully delithiated during
cycling as compared to electrodes that were cycled at lower potentials (U <
0.15 V vs. Li/Li+). Steep Li+ surface-bulk concentration gradients at the
surface of graphite during early stages of intercalation processes, and the
inherent increase of the LixC d-spacing tend to induce local stresses at the
edges of graphene layers, and lead to the breakage of C-C bonds. The exposed
graphite edge sites react with the electrolyte to (re)form the SEI layer, which
leads to gradual degradation of the graphite anode, and causes reversible
capacity loss in a lithium-ion battery.
