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Ultrastable 2D Metallic and Ion Transport Nanotube Highlighted as Cover Paper in Advanced Energy Materials

June 8, 2018

Metallic phase two-dimensional transition metal dichalcogenides (TMDs) are an emerging class of materials with properties that make them highly attractive for fundamental studies of novel physical phenomena and for applications ranging from hydrogen evolution reaction to electrochemical energy storage. However, metallic phase TMDs is in a metastable state and rare in nature. Furthermore, the metallic phase TMDs tend to rapidly restack and transform to semiconducting (2H) phase due to the S-S van der Waals forces, which would significantly reduce the material intrinsic conductivity and decrease the electrons transfer efficiency, and finally inhibit the electrochemical performance.

Therefore, for the first time, Dr. Zhu from Mechanical and Industrial Engineering led her research group to design conductive and porous nanotubes assembled with vertically aligned metallic MoS2 nanosheets, which enormously benefits for avoiding nanosheets restacking, stabilizing metallic phase, and improving ion transport efficiency. The metallic phase of the nanotubes is ultra-stable in the air for more than 120 days. Consequently, this unique highly conducting and porous MoS2 nanotube delivers an ultra-high electrochemical performance with a reversible capacity of ~1100 mA h g-1 at a high current density of 5 A g-1 even after 350 cycles, which is ~2-3 times higher than the commercial graphite (372 mA h g-1). More importantly, the characteristic oxidation peak of metallic MoS2 at 1.5 V on the anodic scan of the cyclic voltammetry curves was identified for the first time in this study. Overall, such metallic material with ultra-high capacity and excellent rate performance is inspiring for researchers to develop high performance electrode for both in energy storage and energy generation. The work on "Lithium‐Ion Batteries: Ion Transport Nanotube Assembled with Vertically Aligned Metallic MoS2 for High Rate Lithium‐Ion Batteries" was featured on the inside back cover in Advanced Energy Materials.