The fundamental understanding of electrochemical lithiation mechanism in two-dimensional layered transition-metal dichalcogenides (TMDs) is essential for the development of high-performance TMD-based anodes for lithium-ion batteries (LIBs). Here, we perform systematic density functional theory calculations to reveal the thermodynamic stability and lithiation dynamics of TMD electrode materials. The calculated results show that there exist two different lithiation mechanisms: one is the reversible intercalation reaction mechanism in which TMD electrodes represented by NbS2 and ZrS2 can maintain their layered structures without significant structural distortions in the lithiation process. The other is the irreversible conversion reaction mechanism where the Li intercalation induces a layer-by-layer structural dissociation of TMD electrodes represented by MoS2 and SnS2 into Li2S and metal nanoparticles. Two contrasting lithiation mechanisms are attributed to a delicate competition between the Li–TMD interaction and metal–chalcogen bonding interaction. Furthermore, we develop a general guiding principle to predict the Li intercalation mechanism of TMD anodes for LIBs.

An artificial synaptic device that can provide color discrimination, image storage, and image recognition is highly required to mimic the human vision for biological robots. All-inorganic halide perovskites have attracted extensive attention for the reason of their high stability and favorable photoelectric properties. In this study, a light-stimulated synaptic phototransistor based on a CsPbBr 3 /organic semiconductor hybrid film is reported. The fabricated CsPbBr 3 film exhibits an island structure, which reduces the hysteresis effectively and at the same time achieves a high specific detectivity of up to 2 × 10 15 Jones. The decay of the photocurrent can be delayed by changing the gate bias, which is essential for achieving high-performance light-stimulated synaptic devices. Due to the outstanding detectivity of the device, the obvious synaptic functions can be observed when triggered by a light signal with a power of 1.6 nW that is much weaker than previous most perovskite-based hybrid synaptic phototransistors under a low operating voltage of −1 V. The electrical power consumption of the device could be as low as 0.076 pJ when the power of light spike was 7.36 nW. Taking into account this characterization, with changing of light intensity or wavelength, the contrast of the image was enlarged, which can further promote the image recognition accuracy. More significantly, this CsPbBr 3 /TIPS hybrid film can be fabricated by facile and low-cost solution processes. This study indicates the great potential of solution-processed perovskite-based light-stimulated synapses for future artificial visual systems.

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Two-dimensional (2D) tin disulfide (SnS2) is a promising anode material for lithium-ion batteries (LIBs) because of its high theoretical capacity. The main challenges associated with the SnS2 electrodes are the poor cycling stability and low rate capability due to structural degradation in the discharge/charge process. Here, a facile two-step synthesis method is developed to fabricate hierarchical MoO3/SnS2 core-shell nanowires, where ultrathin SnS2 nanosheets are vertically anchored on MoO3 nanobelts to induce a heterointerface. Benefiting from the unique structural and compositional characteristics, the hierarchical MoO3/SnS2 core-shell nanowires exhibit excellent electrochemical performance and deliver a high reversible capacity of 504 mA h g-1 after 100 stable cycles at a current density of 100 mA g-1, which is far superior to the MoO3 and SnS2 electrodes. An analysis of lithiation dynamics based on ab initio molecular dynamics simulations demonstrates that the formation of a hierarchical MoO3/SnS2 core-shell heterostructure can effectively suppress the rapid dissociation of shell-layer SnS2 nanosheets via the interfacial coupling effect and the central MoO3 backbone can trap and support the polysulfide in the discharge/charge process. The results are responsible for the high storage capacity and rate capability of MoO3/SnS2 electrode materials. This work provides a novel design strategy for constructing high-performance electrodes for LIBs.

Molybdenum disulfide (MoS2), which is belonged to two-dimensional transition metal chalcogenides, has been considered to have great lithium/sodium storage potential. However, the poor conductivity, unsatisfied mechanical stability as well...