O-doping induced abundant active-sites in MoS2 nanosheets for propelling polysulfide conversion of Li-S batteries

Dual Strategy of Morphology Optimization and Interlayer Expansion in VS2 Cathode Toward High-Performance Mg–Li Hybrid Ion Batteries

“…As can be seen, all XRD patterns are very similar, indicating that the solvothermal temperature has little effect on the phase composition of the samples. Impressively, the diffraction peaks of the as-prepared VS 2 @C are distinctly different from those of 2H-VS 2 (JCPDS 89–1640). , Two obviously formed sharp peaks at 2θ = 9.0° and 17.9° corresponding to the interlayer spacing of 0.98 and 0.50 nm can be observed, which can be indexed to the expanded (001) and (002) planes of VS 2 , respectively. , Notably, three diffraction peaks at 35.7°, 45.2°, and 57.1° can be well assigned to (011), (012), and (110) planes of 2H-VS 2 , suggesting that for the three samples the atomic arrangement along above basal planes are the same as 2H-VS 2 . Moreover, it has been reported that the carbonization of carbon source (such as AA and glucose) results in the formation of amorphous carbon layers in the solvothermal process, which can be in situ coated on the surface of the VS 2 nanosheets to enhance the interaction between VS 2 and carbon. − However, the characteristic peaks of carbon are not obvious in the XRD patterns, which probably is amorphous and deserves further discussion.…”

“…14,32 Notably, three diffraction peaks at 35.7°, 45.2°, and 57.1°can be well assigned to (011), (012), and (110) planes of 2H-VS 2 , suggesting that for the three samples the atomic arrangement along above basal planes are the same as 2H-VS 2 . 30 Moreover, it has been reported that the carbonization of carbon source (such as AA and glucose) results in the formation of amorphous carbon layers in the solvothermal process, which can be in situ coated on the surface of the VS 2 nanosheets to enhance the interaction between VS 2 and carbon. 44−47 However, the characteristic peaks of carbon are not obvious in the XRD patterns, which probably is amorphous and deserves further discussion.…”

“…Over the past few decades, two-dimensional (2D) layered transition metal sulfides (TMSs) with excellent electrochemical properties have attracted the interests of researchers in many fields such as photocatalytic, energy storage, sensor, etc. − As a typical member of TMSs, vanadium disulfide (VS 2 ) with a hexagonal crystal structure has become one of the most investigated electrode materials for LIBs, MIBs, and MLIBs. , Layered VS 2 with a pristine interlayer spacing of 0.576 nm provides abundant diffusion channels for rapid ion (such as Li + and Na + ) insertion/extraction into/from the cathode material. − However, some issues of VS 2 still remain due to the low electronic and ionic conductivity, sluggish diffusion kinetics, and inferior structural stability at the low discharge termination voltage (0.01–0.4 V vs Mg 2+ /Mg) caused by the conversion reaction, , which restricts their practical application in metal ion batteries. To solve the above problems, many modification strategies have been proposed to realize optimizations in specific capacity, rate capability, and cycling stability of VS 2 , such as surface coating, defect engineering, interlayer expansion, composite with other conductive materials, morphology modification, or selection of appropriate charge–discharge voltage window. − Among all the strategies, interlayer expansion and morphology optimization are regarded as effective methods for optimizing the structure and electrochemical performance of VS 2 .…”

Interfacial engineering design induces enriched-defects expediting catalytic conversion kinetics of polysulfides

“…Based on this, a series of tactics, such as phase conversion engineering, amorphization, defect and heterointerface engineering, were attempted to build extra active sites to increase the electrocatalytic activity of MoS 2 . [26][27][28][29][30][31][32] Under the signicant enlightenment of the "Co-Mo-S" active phase theory, Co serving as a metal promoter can partially substitute for Mo atoms at the border of MoS 2 to weaken the intensity of surrounding Mo-S bonds, assisting electrocatalytic reactions. 33 Lin et al synthesized a Co-MoS 2 /G composite and investigated the dominant role of Co sites in sulfur conversion reactions, in which the implantation of Co atoms induces a phase transformation from 2H to 1T and simultaneously generates abundant basal-plane S vacancies, promoting the redox conversion kinetics of sulfur species.…”