The first-principles study on the performance of the graphene/WS2 heterostructure as an anode material of Li-ion battery

The development of high-performance anode materials for rechargeable Li-ion batteries(LIBs) requires not only a large storage capacity, but also the excellent electrical conductivity and high cycle stability. The van der Waals heterostructure can retain the character of the components, and dramatically improve the properties due to the interlayer coupling. In this paper, the electronic structure and stability of the graphene/WS2(G/WS2) heterostructure as well as the Li adsorption and diffusion within the structure are systematically studied by the first-principles calculations. The G/WS2 heterostructure can realize a direct band gap of only 0.01 eV, which is similar to that of graphene (0 eV) and much smaller than that of WS2 (1.89 eV), indicating the metallic property and the amazing electrical conductivity. Moreover, the G/WS2 heterostructure has the much higher stiffness (463.1 N/m) than the 340.5 N/m of graphene and the 106.4 N/mof the WS2 monolayer. The diffusion energy barrier (0.37 eV) of the Li atom in the G/WS2 heterostructure is much lower than that in other anode materials. The in-plane diffusion coefficient (5.54 x 10(-10) m(2)/s) of Li atoms in the G/WS2 heterostructure at 300 K is higher than that on graphene(2.0 x 10(-11) m(2)/s). The largest volume expansion ratio of the G/WS2 heterostructure anode is only 7.4% at the largest Li capacity and ensures the LIB to avoid rapid performance degradation during the charge/discharge cycle. These results can provide conclusive evidence for exploring that the G/WS2 heterostructure should be the promising anode for LIBs. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

The graphene/WS2 heterostructure exhibits metallic properties and amazing electrical conductivity, with low diffusion energy barriers for Li atoms compared to other anode materials, and a lower volume expansion ratio, making it a promising candidate for LIB anodes.