Here , and µ(Li) represent the energies of and number Li added WS 2 /graphene heterostructure, and chemical potential of bulk Li metal, respectively. The obtained OCV profile is shown in Figure . From the voltage profile it is clear that the potential varies from 0.55 -0.25 V for x = 1 -6. The average OCV for the Li concentration up to 0.22 is 0.35 V. However, the voltage profile also reveals that the lithiationdelithiation potential has been significantly reduced when the Li concentration is higher in the heterostructure, i.e., the OCV ≈0V when x = 0.93. Thus, overall the average value of the voltage = 0.18 V. This average OCV value for the lithiation of WS 2 /graphene heterostructure falls in the range of typical anode materials of LIBs. Therefore, we confirmed that WS 2 /graphene heterostructure is suitable to use as an anode of LIBs. It is worthy to mention that the average OCV value of this heterostructure is far better than many of the other 2D heterostructures such as HfS 2 /graphene, h-BN/black phosphorene, blue phosphorene/MS 2 (M=Ta, Nb) reported earlier. The lower OCV of this electrode also offers a good possibility to assemble it along with high voltage cathode materials such as LiCoO 2 to design high voltage LIBs.