Vacancy engineering of MoS2−X @NCNTs for efficient storage of zinc ions

Abstract

Zinc-ion batteries are receiving interest due to their high level of safety and eco-friendliness. However, the sluggish diffusion kinetics of zinc ions in the electrode limit its practical application. In this paper, rapid Zn2+ diffusion in the MoS2−X @NCNTs cathode is achieved by utilizing the S vacancies generated under a H2/Ar atmosphere and N-doped carbon nanotubes (NCNTs) derived from the pyrolysis of polyethylene and melamine. The presence of S vacancies significantly reduces the diffusion barrier of Zn2+, thereby promoting the transport of Zn2+ ions. MoS2−X @NCNTs cathode demonstrates an impressive discharge specific capacity of 220 mAh g−1 (0.1 A g−1) and a remarkable reversible capacity of 173 mAh g−1 (3 A g−1). Furthermore, the reduced adsorption energy of MoS2−X nanosheets leads to Zn2+ tending to preferentially insert S vacancies, resulting in a larger capacity than pure MoS2. This work realizes efficient storage of Zn2+ in 2D disulfides through carbon frameworks and S vacancies. In addition, flexible zinc batteries with MoS2−X @NCNTs cathodes have promising applications in wearable devices.