Effects of Pre-Lithiation on the Electrochemical Properties of Graphene-Like Graphite

Pre-lithiation of graphene-like graphite (GLG) was conducted and its effects on structural and electrochemical properties of GLG were investigated. When lithium naphthalenide was used for the pre-lithiation, a large amount of the solution was required for the intercalation of lithium ions into GLG. Moreover, binder in the composite electrode was degraded by the pre-lithiation and the discharge capacity considerably decreased. On the other hand, prelithiation of GLG with lithium metal resulted in the increase of interlayer distance to similar value to that of electrochemically full-charged GLG, even though the amount of the added lithium metal was equivalent to only 28% or 38% of SOC of the GLG. In addition, the decreases in the charge capacity were more than those expected from the amounts of lithium metal. The full and immediate interlayer expansion by the pre-lithiation of GLG suppressed the repeated exfoliation and re-formation of SEI unlike electrochemically charged GLG. Since the discharge capacities were almost identical to that of the pristine GLG, the coulombic efficiency was greatly improved. The issue of low coulombic efficiency of GLG at the initial cycle can be conquered by this method, and it would increase the probability of the practical application of GLG. (C) The Electrochemical Society of Japan, All rights reserved.