Unraveling MoS₂ and Transition Metal Dichalcogenides as Functional Zinc‐Ion Battery Cathode: A Perspective

Abstract

Transition metal dichalcogenide (TMD) has been widely studied as promising material in a wide variety of energy-related applications. [14-17] TMD, which comprises of transition metal (M) and chalcogen (X), is often regarded as an inorganic analogue to the graphite. Each TMD layer, with the stoichiometric composition of MX 2 , is arranged with a central layer of M atoms that is sandwiched with two layers of X atoms. As such, each TMD layer can be considered to be three atoms thick (X-M-X configuration). One of the interesting aspects of TMD is the interlayer bonding between two X-M-X layers, whereby weak Van der Waals interactions are typically responsible for holding the structure in place. [18-20] The existence of this interlayer bonding allows the exfoliation of bulk TMD into single-or few-layer TMD. [21-23] Furthermore, due to this unique 2D configuration, the interlayer spacing of TMD is available for the accommodation of intercalating ion. This is particularly suitable for alternative battery technique that employs larger hydrated metal ions, i.e., ZIB. [24-27] Among the TMD family, MoS 2 is perhaps the most representative member with an interlayer spacing of 0.62 nm, which, in theory, should be able to accommodate a diffusing hydrated Zn 2+ in its framework. Despite the suitable interlayer spacing of MoS 2 for Zn 2+ storage (when we consider Mo-Mo layer separation), there are still limited reports that can successfully demonstrate MoS 2 as viable ZIB cathode. Ironically, most reports on MoS 2 as ZIB cathode have pointed toward the poor Zn 2+ storage by pristine MoS 2 (≈10-40 mAh g −1), which suggests the incompatibility of MoS 2 as ZIB cathode despite the sufficient interlayer spacing. [28] Such perplexity between the seemingly suitability of these TMDs as ZIB cathode from the theoretical perspective and the poor Zn 2+ storage performance from the actual employment of TMDs as ZIB cathode deserves significant research attention. In this perspective review, we will discuss the main challenge of employing MoS 2 and TMDs as ZIB cathode, and we will summarize the recent development of MoS 2 and TMDs in ZIB research. The main focus of this perspective review is to propose possible modification strategies for MoS 2 and TMDs so as to elicit reasonable Zn 2+ storage ability in this material family. Four key modification strategies are identified, i.e., 1) interlayer engineering, 2) defect engineering, 3) hybridization, and 4) phase engineering, which could "activate" these pristine MoS 2 and TMDs toward satisfactory Zn 2+ storage. Lastly, we The zinc-ion battery (ZIB) is considered as one of the most important alternative battery chemistries to date. However, one of the challenges in ZIB development is the limited selection of materials that can exhibit satisfactory Zn 2+ storage. Transition metal dichalcogenides (TMDs) are widely investigated in energy-related applications due to their distinct physical and chemical properties. In particular, the wide interlayer spacings for these TMDs are particularly attractive a...

A nano interlayer spacing and rich defect 1T-MoS2 as cathode for superior performance aqueous zinc-ion batteries

“…43,44 Besides, the Zn 2+ diffusion barrier of 1T phase MoS 2 is much lower than its 2H phase. 45 Therefore, 1T-MoS 2 as a cathode material for zinc-ion batteries may manifest superior specific capacity and decent cycle performance. Most of the reports on MoS 2 as a ZIBs cathode use modification strategies (such as interlayer engineering, defect engineering) to enhance Zn 2+ storage.…”

Two‐Dimensional Cathode Materials for Aqueous Rechargeable Zinc‐Ion Batteries†

“…Its interlayer spacing is 0.62 nm, which can accommodate the diffusion of hydrated Zn 2+ in its frame. [ 64‐65 ] There are two main structural phases of MoS 2 , 2H and 1T MoS 2 , which are differed by their metal coordination geometry and stacking sequence. 2H MoS 2 is semiconducting, and has a trigonal prism Mo/S coordination structure with an indirect bandgap of about 1.3 eV, [ 66 ] while 1T MoS 2 is metallic, and has a octahedron Mo/S coordination structure.…”

Recent Advances in Transition Metal Dichalcogenide Cathode Materials for Aqueous Rechargeable Multivalent Metal-Ion Batteries

“…Despite these benefits, the poor rate performance and cyclic stability of TMDs due to their low ionic conductance and large volume expansion limit their application as cathode materials in AMMIBs. Furthermore, the irreversible side effects during the charging and discharging processes decrease the coulombic efficiency of TMDs [59]. These disadvantages severely limit the application of TMDs as cathode materials for AMMIBs.…”

“…The main viewpoint in this review is centered on the TMD materials as a cathode and multivalent metal ions dissolved in water as a electrolyte, respectively, which is distinctively different from most previous review articles. Figure 1a,b highlight some recent reviews and the numbers of publications on TMDs over the last 10 years [36,40,41,47,48,[50][51][52][53][54][55][56][57][58][59]. The number of publications on various TMD materials has been steadily increased from the year of 2010.…”