Ion Transport Nanotube Assembled with Vertically Aligned Metallic MoS₂ for High Rate Lithium‐Ion Batteries

Abstract

by the large volume change and the poor intrinsic conductivity with a direct bandgap of ≈1.9 eV significantly inhibits the further applications of 2H MoS 2 on lithium-ion batteries. [8,9] One of the best and typical strategies to ameliorate the structural stability and electrical conductivity of MoS 2 based anode is to fabricate hybrid 2H MoS 2 nanocomposites with conductive carbonaceous materials, such as carbon fibers, graphene, and carbon nanotubes. These hybrid MoS 2 -carbon nano composites (MCNs) could deliver a decent capacity of ≈900 mA h g −1 at 1 A g −1 current density on lithium-ion batteries for 100 cycles. [2,10,11] Unfortunately, this strategy also induces new constraints to the MCNs' applications on lithium-ion batteries, such as reducing the mass loading of MoS 2 , consuming more electrolytes, raising the electrode cost, and increasing the reaction barrier between lithium-ion and MoS 2 . [12] Even though carbon source can improve the conductivity of the electrode, the intrinsic insulating property of 2H MoS 2 remains unchanged, which will significantly limit its rate performance and impede the utilization of the active MoS 2 . Recently, the metastable metallic phase (1T or 1T′) MoS 2 has emerged with promising potential on lithium-ion storage field. As reported, [8,[13][14][15] benefited from its different Mo and S atom coordination of octahedral structure with dense intercalation sites, metallic phase MoS 2 owns five orders of magnitude higher electrical conductivity than that of 2H MoS 2 . This high intrinsic conductivity will be beneficial for the performance of metallic MoS 2 electrode in the following two aspects. On one hand, pure metallic MoS 2 can be directly applied as an anode electrode on lithium-ion batteries without adding any conductive carbon sources, which would facilitate the electrochemical storage fundamental mechanism studying of metallic MoS 2 . On the other hand, the utilization of active MoS 2 can also be maximized, and the lithium-ion charge/discharge capacity could be tremendously enhanced at high current density, therefore intensely improves the rate performance as well as the reversible capacity of metallic MoS 2 as an anode electrode. However, the conventional preparation methods of metallic MoS 2 by alkali metal intercalation and exfoliation are complicated, unstable, and dangerous. [13] Recent reports provided several new strategies to prepare metallic MoS 2 by solvothermal method, [9,16,17] which stabilized the metallic MoS 2 by interlayer Metallic phase molybdenum disulfide (MoS 2 ) is well known for orders of magnitude higher conductivity than 2H semiconducting phase MoS 2 . Herein, for the first time, the authors design and fabricate a novel porous nanotube assembled with vertically aligned metallic MoS 2 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, ...

Metallic MoS2 for High Performance Energy Storage and Energy Conversion

“…Recently, our group published a fabrication technique of metallic MoS 2 by the reaction of molybdenum oxide and thioacetamide in ethanol (Figure c). The obtained metallic MoS 2 can maintain its stability in air for more than 120 days and even after electrochemical charge/discharge …”

“…However, based on this strategy, scientists proved that by autoclave methods, under a certain pressure with proper chemical, the metallic phase MoS 2 could also be achieved. This method could be scalable and does not need specific facilities …”

“…Song et al claimed that when grown on graphene, the metallic MoS 2 could be efficiently confined, and prevented from aggregation. Zhu and co‐workers reported a similar strategy to avoid MoS 2 aggregation, by designing a tube structure assembled with metallic MoS 2 nanosheets. This design will also help to avoid MoS 2 aggregation.…”

“…However, the layer distance can vary and be as large as ≈1 nm with the variation in reaction solvent such as water, ethanol, and DMF in autoclave . The Mo atom has a hexagonal arrangement with the distance ranging from 0.28 to 0.48 nm (Figure e) . Selected area electron diffraction (SAED) pattern (Figure f) is another characterization method for MoS 2 based on HRTEM result.…”

Enhanced Li‐Ion‐Storage Performance of MoS2 through Multistage Structural Design

“…[10] This inspires us to consider: whether the multistage structural design concept applicable to the folded proteins can be employed herein to create the advanced electrode materials for LIBs. [13][14][15][16] In recent years, various MoS 2 composites, [17][18][19][20][21][22][23][24][25][26][27] including MoS 2 /C, [19,20,23,24] SnS 2 /MoS 2 /CFC, [21] MoO 2 @MoS 2 [22] and S-MoS 2 @α-Fe 2 O 3 [26] have been widely exploited as important anode materials for lithium ion batteries (see Table S1). [13][14][15][16] In recent years, various MoS 2 composites, [17][18][19][20][21][22][23][24][25][26][27] including MoS 2 /C, [19,20,23,24] SnS 2 /MoS 2 /CFC, [21] MoO 2 @MoS 2 [22] and S-MoS 2 @α-Fe 2 O 3 [26] have been widely exploited as important anode materials for lithium ion batteries...…”