Enhanced and Faster Potassium Storage in Graphene with Respect to Graphite: A Comparative Study with Lithium Storage

The mechanisms, extent, and rate of K-storage in graphenic and graphitic carbons, as direct comparisons with Li-storage in the same structures/materials, in terms of the effects of dimensional scale and presence of surface and exposed edge sites have been brought to the fore via DFT-based simulations, duly complemented and supplemented by experimental studies. The simulation indicates feasibilities toward K-storage on single-layer graphene (SLG) at a concentration greater than that in graphite (i.e., beyond KC8), the formation of more than one layer of K on SLG, and K-storage on both the surfaces of SLG, unlike that for Li-storage. Simulations done with graphene nanoribbons (GNRs) indicate that K can get hosted on the graphene surfaces and at the exposed “stepped” edges, in addition to the “classical” K-intercalation in-between the constituent graphene layers. Accordingly, the computation studies indicate considerably enhanced K-storage “specific capacity” of GNR, as compared to bulk graphite, with the ca...