According to foreign media reports, a team of scientists from the Department of Electrical and Electronic Information Engineering at Toyohashi University of Technology in Japan synthesized a reactive sulfur-containing material and carbon nanofibers using a low-cost simple liquid phase method CNF) Composite materials. The researchers used the liquid-phase method to make sulfur-CNF composite materials, and then made all-solid-state lithium-sulfur batteries, which have higher discharge capacity and better cycle stability than lithium-ion secondary batteries. Therefore, in the future, such solid-state lithium-sulfur batteries will be able to be used in electric vehicles.
The lithium-ion secondary battery that won the Nobel Prize in Chemistry last year has been widely used in smartphones, electric vehicles and other fields. In recent years, due to the increase in the number of hybrid vehicles and electric vehicles, all-solid-state batteries have also received attention as the next-generation batteries. In particular, the energy density of the all-solid-state lithium-sulfur battery is 5 times that of the traditional lithium-ion secondary battery, so it has attracted much attention. However, sulfur is an insulator, which limits its application to battery equipment. To solve this problem, sulfur must be equipped with a path that can conduct ions and electrons.
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The research team proposed a cathode composite material composed of a sulfur-containing active material and carbon nanofibers (CNF, prepared by electrostatic assembly), which can be uniformly combined with other materials in solution . An all-solid-state lithium-sulfur battery was prepared by using a sulfur-CNF composite material and a Li2S-P2S5-LiI solid electrolyte synthesized by an electrochemically stable liquid phase method. The discharge capacity of the battery is equivalent to the theoretical capacity of sulfur. Maintain a higher capacity.
The researchers explained the characteristics of the battery: "In order to produce a high-performance all-solid lithium-sulfur battery, it is necessary to combine an appropriate amount of sulfur-containing active material with an appropriate amount of carbon material. Generally speaking, sulfur-carbon composite materials are mixed mechanically, Special organic solution liquid mixing and complex method (sulfur combined with porous carbon material with high specific surface area) synthesis. However, there are few reports that the capacity of the all-solid lithium-sulfur battery can be almost equivalent to the theoretical capacity of sulfur, and the cycle stability is also High. Therefore, we are committed to adopting a low-cost simple electrostatic adsorption method to uniformly combine nanomaterials to make a sulfur-carbon composite material. The research also confirmed that the sulfur-carbon composite material synthesized by electrostatic adsorption method can be The flake form accumulates on the carbon nanofibers, and finally we created an all-solid-state lithium-sulfur battery, and found that sulfur is fully utilized as an active material. Another advantage is that the production cost of this sulfur-carbon composite material is higher than traditional processes Low manufacturing cost. "
The electrostatic adsorption method uses a polyelectrolyte to adjust the charge on the surface of the particles, so that the larger parent particles and the smaller particles can be adsorbed together by static electricity, thereby inducing electrostatic effects. Although there have been reports of designing various ceramic composites using electrostatic adsorption before, it is difficult to adjust the charge on the sulfur surface. However, the research team successfully adjusted the charge using a chemical reaction in which sodium sulfide (Na2S) and sulfur (S) reacted in ion-exchanged water to form water-soluble Na2S3. Therefore, this study applied the basic principles of electrostatic adsorption to realize a new type of chemical process.
The method can prepare sulfur-carbon composite materials, has low cost and is relatively simple, and is suitable for large-scale production. All-solid-state lithium-sulfur batteries made of sulfur-containing active materials will be put into practical use, and the energy density of electric vehicles, household and commercial large-scale power batteries is also expected to increase exponentially. (Yu Qiuyun)
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