Ion Transport Nanotube Assembled with Vertically Aligned Metallic MoS_2 for High Rate Lithium-Ion Batteries

摘要

Metallic phase molybdenum disulfide (MoS2) is well known for orders of magnitude higher conductivity than 2H semiconducting phase MoS2. Herein, for the first time, the authors design and fabricate a novel porous nanotube assembled with vertically aligned metallic MoS2 nanosheets by using the scalable solvothermal method. This metallic nanotube has the following advantages: (i) intrinsic high electrical conductivity that promotes the rate performance of battery and eliminates the using of conductive additive; (ii) hierarchical, hollow, porous, and aligned structure that assists the electrolyte transportation and diffusion; (iii) tubular structure that avoids restacking of 2D nanosheets, and therefore maintains the electrochemistry cycling stability; and (iv) a shortened ion diffusion path, that improves the rate performance. This 1D metallic MoS2 nanotube is demonstrated to be a promising anode material for lithium-ion batteries. The unique structure delivers an excellent reversible capacity of 1100 mA h g(-1) under a current density of 5 A g(-1) after 350 cycles, and an outstanding rate performance of 589 mA h g(-1) at a current density of 20 A g(-1). Furthermore, attributed to the material's metallic properties, the electrode comprising 100% pure material without any additive provides an ideal system for the fundamental electrochemical study of metallic MoS2. This study first reveals the characteristic anodic peak at 1.5 V in cyclic voltammetry of metallic MoS2. This research sheds light on the fabrication of metallic 1D, 2D, or even 3D structures with 2D nanosheets as building blocks for various applications.