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Research progress of high power and long life lithium - sulfur batteries

- Jan 07, 2019 -

Structure of the Chinese academy of sciences, fujian material research institute researcher at the state key laboratory of structural chemistry Wang Ruihu group and wenzhou university professor Yang Zhi cooperation, the water vapor etching of porous NbS2 and high conductive iodine doped graphene (IG) sulfur compound to ternary hybrid anode system, was synthesized by IG package type sandwich NbS2 @ S @ IG the anode material. In this special sandwich structure, the high polarity and strong affinity of layered NbS2 promote the physical interception and chemical adsorption of polysulfide, and solve the problem of polysulfide dissolution and shuttle effect in a synergistic way. The high conductivity and porosity of NbS2 increase the interfacial charge transfer and ion transfer, thus improving the electrochemical kinetics of the REDOX reaction of li-s batteries. The sandwich structure surrounded by IG can not only make a close contact between the sulfur substance and the laminar NbS2 (or IG), but also can withstand a great volume fluctuation of sulfur during charging and discharging. Li-s battery assembled by nbs2@s@ig shows excellent cycling stability under the high magnification of 20-40c.

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Schematic diagram of composite material NbS2@S@IG

NbS2 and sulfur powder slurry in CSS were mixed with IG and then freeze-dried. Melting diffusion of sulfur produced nbs2@s@ig, in which nbs2@s was completely surrounded by IG.

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Schematic diagram of reasonable mechanism of sulfur imbedded in NbS2 interlayer

In the process of discharge, due to the strong interface interaction between NbS2 and Li2S8, sulfur is gradually transformed into soluble Li2S8 material, and then they are adsorbed on the edge position and surface of conductive NbS2 nanosheet.

With the urgent demand for high-capacity energy storage devices for portable electronic devices and emerging electronic products such as electric vehicles, li-s battery (li-s) is regarded as one of the most promising high-capacity storage systems due to its high theoretical specific capacity and energy density, as well as its low cost and environmental friendliness. However, there are still some technical challenges in the commercial application of li-s battery, such as the insulation of solid sulfide, the shuttle effect of soluble long-chain polysulfide, and the large volume change of sulfur during charging and discharging. These problems usually result in low sulfur utilization, poor cycle life, and even a series of safety problems. How to greatly improve the stability of li-s battery and increase its high-power discharge performance has become one of the hot spots of current research.

Structure of the Chinese academy of sciences, fujian material research institute researcher at the state key laboratory of structural chemistry Wang Ruihu group and wenzhou university professor Yang Zhi cooperation, the water vapor etching of porous NbS2 and high conductive iodine doped graphene (IG) sulfur compound to ternary hybrid anode system, was synthesized by IG package type sandwich NbS2 @ S @ IG the anode material. In this special sandwich structure, the high polarity and strong affinity of layered NbS2 promote the physical interception and chemical adsorption of polysulfide, and solve the problem of polysulfide dissolution and shuttle effect in a synergistic way. The high conductivity and porosity of NbS2 increase the interfacial charge transfer and ion transfer, thus improving the electrochemical kinetics of the REDOX reaction of li-s batteries. The sandwich structure surrounded by IG can not only make a close contact between the sulfur substance and the laminar NbS2 (or IG), but also can withstand a great volume fluctuation of sulfur during charging and discharging. Li-s battery assembled by nbs2@s@ig shows excellent cycling stability under the high magnification of 20-40c.