Three‐Dimensional Flower‐Like MoS₂@Carbon Nanotube Composites with Interconnected Porous Networks and High Catalytic Activity as Cathode for Lithium‐Oxygen Batteries

Abstract

Lithium-oxygen (LiÀO 2 ) batteries show great potential to become one of the most promising energy-storage and conversion systems owing to their ultrahigh theoretical specific energy (~3505 Wh kg À1 ). However, commercialization of Li-O 2 batteries is constrained by a large charging overpotential caused by the sluggish electrode kinetics and low conductivity of the discharge product, resulting in unsatisfied energy efficiency and poor cyclability. In this paper, aiming to address these issues, we propose unique orderly arranged three-dimensional (3D) flower-like MoS 2 nanospheres combined with carbon nanotubes (f-MoS 2 @CNTs) as an efficient cathode catalyst for LiÀO 2 batteries. Homogeneously dispersed CNTs on the surface of MoS 2 can not only increase the electrical conductivity and thereby lowering the charge overpotential, but also maintain the structural integrity of the cathode, improving the cyclic reversibility. Benefiting from the unique 3D flower-like structure with an interconnected porous network and the excellent catalytic activity of MoS 2 , the LiÀO 2 battery with a f-MoS 2 @CNTs catalyst achieved a lower charge overpotential (1.02 V) and exhibited excellent cyclic reversibility with 141 cycles until the terminal voltage decreased below 2 V at a current density of 500 mA g À1 . The reasonable design of the f-MoS 2 @CNTs-based cathode thus provides a promising solution for practical applications of LiÀO 2 batteries.

Bi2S3/Ketjen Black as a Highly Efficient Bifunctional Catalyst for Long‐Cycle Lithium‐Oxygen Batteries

“…[28] Long et al found that LiÀ O 2 battery catalyzed by MoS 2 /CNTs can be cycled for 141 cycles at 1000 mA h g À 1 . [26] These two results suggest that the sulfides can be the highly effective catalysts for LiÀ O 2 batteries. Moreover, some bismuth chalcogenides have been applied to several catalytic fields such as ORR, [29] OER, [30] hydrogen evolution reaction (HER) [31] and carbon dioxide conversion [32] due to the good catalytic abilities.…”

“…Long et al. found that Li−O 2 battery catalyzed by MoS 2 /CNTs can be cycled for 141 cycles at 1000 mA h g −1 . These two results suggest that the sulfides can be the highly effective catalysts for Li−O 2 batteries.…”

“…On the other hand, metal compounds, such as metal oxides, [17,18] metal nitrides, [19,20] metal carbides [21,22] and metal sulfides, [23,24] have been widely used as the catalysts due to their excellent catalytic ability. Compared with other compounds, only few metal sulfides were reported as the catalysts for LiÀ O 2 batteries, such as Co 9 S 8 , [23] Bi 2 S 3 , [25] MoS 2 [26] and FeS. [27] Hu et al reported a NiCo 2 S 4 nanorod arrays supported on carbon textile, which showed a good catalytic activity that enabling a long cycle life of 500 cycles at 1000 mA h g À 1 with a low overpotential.…”

“…On the other hand, metal compounds, such as metal oxides, metal nitrides, metal carbides and metal sulfides, have been widely used as the catalysts due to their excellent catalytic ability. Compared with other compounds, only few metal sulfides were reported as the catalysts for Li−O 2 batteries, such as Co 9 S 8 , Bi 2 S 3 , MoS 2 and FeS . Hu et al.…”

Activating MoS2 Nanoflakes via Sulfur Defect Engineering Wrapped on CNTs for Stable and Efficient Li‐O2 Batteries

“…[ 24 ] The dispersed 1D CNT can form 3D porous interconnected networks for fast electron transfer and abundant void volume, which aids in maintaining the cathode integrating during cycling, and thus superior rate capability and cyclic reversibility could be achieved. [ 24d,25 ] However, it is believed that carbon materials would react with electrolyte and even the discharge products under relatively high potentials, leading to the obvious battery performance decay with the continuous formation and accumulation of by‐products. [ 26 ] Hence, an effective protection strategy needs to be applied to refrain from the carbon material corrosion in LOBs.…”