Approaching the Theoretical Sodium Storage Capacity and Ultrahigh Rate of Layer‐Expanded MoS₂ by Interfacial Engineering on N‐Doped Graphene

Abstract

With the development of economy and society, the energy storage devices possessing both high energy and power densities are urgently desired to meet the requirement of fast-charging electronics, electric vehicles, and smart grids. [1] Although rechargeable batteries have been widely used due to its high energy density, the sluggish kinetics restricts its power density. [2] On the other hand, supercapacitors show high power density and good cycle stability but a rather low energy density. [3] Recently, the hybrid capacitors combining the battery-type anodes and the capacitor-type cathodes have attracted much attention for achieving both high energy and power densities. [4] Compared with lithium ion capacitors, sodium ion capacitors (SICs) are more attractive due to the low cost and source abundance of sodium. [5] However, most anode materials suffer from poor electrochemical kinetics because of the larger ion diameter of Na + than Li +. [6] Therefore, developing appropriate electrode materials to meet the high-capacity and high-power requirements of SICs is urgently needed. Molybdenum disulfide (MoS 2), a typical 2D transition metal dichalcogenides stacked by van der Waals force, has attracted great attention for electrochemical sodium storage due to its high capacity of 670 mAh g −1. [7] However, its high theoretical capacity is hardly realized because of the low conductivity and limited interlayer ion transport kinetics. [8] More seriously, these intrinsic drawbacks result in poor rate performance and cycle stability, further restricting its practical application for highpower devices. [9] For metal compounds (e.g., metal oxides and metal sulfides) as electrode materials for ion batteries, the most common route to solve the conductive issue is compositing with conductive carbon scaffolds such as carbon nanotube, [10] graphene, [11] and carbon fiber. [12] Specially, the strong interfacial interaction between two phases has been proven to play important roles for improving the electrochemical kinetics and cycle stability. [13] To form the strong interaction, the carbon scaffolds are usually functionalized with oxygen-containing functional groups to improve the surface compatibility, simultaneously resulting Molybdenum disulfide (MoS 2) holds great potential for sodium storage due to its high theoretical capacity of 670 mAh g −1. However, its theoretical capacity is hardly realized because of low conductivity, sluggish electrochemical kinetics, and unsatisfied structural stability. Herein, a polyaniline-mediated interfacial engineering strategy for the growth of interlayer-expanded MoS 2 nanoflowers on N-doped graphene "land" (E-MoS 2 /NG) using Mo 7 O 24 6− anions adsorbed on positively charged polyaniline as the "seeds" is reported. The strong interfacial interaction between MoS 2 and graphene through MoN bonds as well as ultrathin interlayer-expanded MoS 2 can significantly improve the electrochemical kinetics and structural stability. As a result, E-MoS 2 /NG with a high MoS 2 content of 90 wt% shows a high ca...

Crosslinking Nanoarchitectonics of Nitrogen‐doped Carbon/MoS2 Nanosheets/Ti3C2Tx MXene Hybrids for Highly Reversible Sodium Storage

“…For comparison, without PEI, the growth of MoS 2 on Ti 3 C 2 T x can be also realized, but with aggregation (Figure S4, Supporting Information). Additionally, the high‐resolution (HR)TEM image of MoS 2 /Ti 3 C 2 T x @NC presented in Figure 2g demonstrates the rational combination of MoS 2 and Ti 3 C 2 T x , and the interlayer spacing of 0.63 nm is also in line with the (002) plane of MoS 2 [11] . Besides, the polycrystalline feature of the MoS 2 was also confirmed via the selected area electron diffraction (SAED) pattern [21] .…”

“…Specifically, morphology control and structure optimization are believed to promote the wetting of electrolyte, charge transfer, and alleviation of structure change upon the intercalation of Na + [7a] . The combination with carbonaceous materials, the highly conductive networks and efficient buffering matrix allow high electrochemical performance of the hybrid electrode, mainly originating from the decreased polarization and improved structural stability [11] . In general, individual structure design and component optimization can indeed modify the sodium storage performance of MoS 2 ‐based electrodes, but to a limited extent.…”

MOF-Derived ZnS Nanodots/Ti3C2Tx MXene Hybrids Boosting Superior Lithium Storage Performance

“…In addition, the low lithiation potential (~ 0.1 V vs. Li + /Li) of graphite enables the risk of lithium dendrites formation, which may trigger internal short and thus lead to safety concern [3,4]. Transition metal sulfides (TMSs) [5][6][7], such as MoS 2 [8,9], SnS 2 [10,11], CoS [12], and ZnS [13], have received considerable attention as promising candidate anode materials to replace graphite on account of their high specific capacity and moderate working potential. Among TMSs, ZnS is one of the most attractive anode candidates for lithium storage because of its high theoretical lithium storage capacity, non-toxicity, and low cost.…”

Enhancing the Electrochemical Performance of Sodium‐Ion Batteries by Building Optimized NiS2/NiSe2 Heterostructures

“…which can satisfy the 5C requirements. In previous studies, [15][16][17][18][19] transition metal sulfides (TMS) and selenides (TMSe) based on conversion-type chemistries have been regarded as promising anode materials owing to their large theoretical capacity, suitable interlayer distance, appropriate working potential, low diffusion energy barriers, and designable fast transfer path of ion/electron, which yields high performance in SIBs. However, the intrinsically physical features of the low intrinsic electrical conductivity and large volume variation caused pulverization and structural changes in the TMS and TMSe anode materials during cycling processes.…”