MoS2 is a promising electrode materials for sodium-ion batteries. In the structure of MoS2, there is adequate “space” between the MoS2 layers interconnected with weak van der Waals force to accommodate Na ions during charging. It turns out that MoS2 allows Na ions to intercalate therein without a significant volume expansion (1); which enables MoS2 to be a promising electrode material for rechargeable batteries (2). However, the number of the electrons can be accommodated in the S-MoS layer is limited while the structural framework remains stable. It has been shown that up to 1.5 electrons can be stored per unit formula in MoS2 before the layered structure collapses (3). Meanwhile, there is a structural transition between trigonal 2Hand octahedral 1T-AMoS2 (A = Li, Na, K, etc.) accompanied by an electronic state change from semiconducting to metallic observed upon alkali-metal ion’s intercalation (4). Recent developments of in-situ transmission electron microscopy (TEM), as one unique tool to conduct real time structural measurements under the dynamic electrochemical reaction processes. (5) Such in-situ or in-operando measurements make it possible to analyze and tackle the intricacies of the sodiation mechanism in electrode materials during charge/discharge cycles.
[1]
Liping Wang,et al.
Atomic-Scale Probing of the Dynamics of Sodium Transport and Intercalation-Induced Phase Transformations in MoS₂.
,
2015,
ACS nano.
[2]
Liquan Chen,et al.
Atomic-scale clarification of structural transition of MoS₂ upon sodium intercalation.
,
2014,
ACS nano.
[3]
John P. Sullivan,et al.
In Situ Observation of the Electrochemical Lithiation of a Single SnO2 Nanowire Electrode
,
2010,
Science.
[4]
E. Benavente,et al.
Intercalation chemistry of molybdenum disulfide
,
2002
.