Next, to understand the insights of lithiation of WS 2 /graphene heterostructure, we introduced Li-atoms sequentially on various available sites of the former. In this particular heterostructure broadly we considered three possible cases namely (i) above the WS 2 surface, (ii) at the interface of WS 2 and graphene, and (iii) above graphene layer (refer Figure , Supporting Information). Moreover, the careful analysis reveals that the added Li can interact with WS 2 (with both exposed site and interface) in three possible ways such as at the hollow site constituted by three S and one W (denoted as T W -site), hollow site formed by three S atoms (also known as T S -site) and bridge site. Hence, we also considered all these possibilities while adding Li to the interface as well as above WS 2 layer (see Figure , Supporting Information).