Preparation method for lithium sulfide self-supporting carbon sphere/carbon nanofiber composite material, and lithium-sulfur battery

Abstract

The invention discloses a preparation method for a lithium sulfide self-supporting carbon sphere / carbon nanofiber composite material, and a lithium-sulfur battery. The preparation method comprises thesteps of S1, preparing lithium sulfate / glucose / bacterial cellulose hydrogel composite material; and S2, converting glucose in the lithium sulfate / glucose / bacterial cellulose hydrogel composite material into carbon spheres, enabling lithium sulfate to be better coated with a carbon material, slowing down diffusion of polysulfide lithium, and converting bacterial cellulose into carbon nanofibers, so that the carbon sphere / carbon nanofiber aerogel composite material is formed. According to the technical scheme, an adhesion agent does not need to be added, and then an electrode is formed by direct self-supporting after carbonization; and meanwhile, a carbon sphere structure and a carbon nanofiber network structure can be constructed, and lithium sulfide nanoparticles in the structure are effectively coated, so that the electron conductivity in the electrode can be improved, the transmission efficiency of electrons in the electrode is improved, the "shuttle effect" is inhibited, and the performance of the lithium-sulfur battery is improved.

Description

technical field [0001] The invention belongs to the technical field of lithium-sulfur batteries, and in particular relates to a preparation method of a lithium sulfide self-supporting carbon sphere / carbon nanofiber composite material and a lithium-sulfur battery. Background technique [0002] In the past few decades, the energy shortage problem has become more and more serious. With the development of science and technology, people put forward higher requirements for energy storage systems and chemical power sources. In recent years, lithium-sulfur batteries have great prospects in commercial applications due to their theoretical specific capacity of 1672mAh / g, energy density of 2600Wh / kg, huge sulfur reserves, low cost, and no pollution to the environment. The battery is considered to be one of the most promising next-generation lithium-ion batteries. [0003] At present, there are still some problems in the development of lithium-sulfur batteries: first, the electronic c...

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Problems solved by technology

[0003] At present, there are still some problems in the development of lithium-sulfur batteries: first, the electronic conductivity of sulfur and its corresponding sulfides at room temperature is very low, resulting in serious attenuation of battery cycle capacity; second, the intermediate product lithium polysulfide ( Li 2 S x , 4≤x≤8) is easily dissolved in the organic electrolyte and causes the "shuttle effect", resulting in the loss of active materials and reducing the electrochemical performance of the battery; third, a large volume change will occur during the charging and discharging of the sulfur electrode ( about 80%), will cause the electrode structure to collapse, and even lead to battery damage

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