Core-shell structured lithium-sulfur battery cathode material and preparation method thereof

Abstract

The invention discloses a core-shell structured lithium-sulfur battery cathode material, which is characterized by having a core-shell structure. The core is nanoscale elemental sulfur. There can be one or more cores. The layer outside the core is loose good-conductivity carbon nanotube, carbon nanofiber or a mixture of carbon nanotube and carbon nanofiber. The outermost layer is the shell which is composed of citric acid or asphalt cracked carbon and has certain hardness. The method of the invention has advantages of simple preparation and low cost, and is beneficial to large-scale production and is conducive to realize commercialization of the lithium-sulfur battery cathode material.

Description

technical field [0001] The invention relates to the technical field of cathode materials for lithium-sulfur batteries, and more specifically relates to a cathode material for lithium-sulfur batteries with a core-shell structure and a preparation method thereof. Background technique [0002] The theoretical capacity of the electrode of the lithium-sulfur battery reaches 1675mAh / g, and the energy density of the battery is as high as 2600Wh / kg, which is unmatched by various secondary batteries under research. However, the conductivity of elemental sulfur is weak, and the dissolution of polysulfides in the electrolyte, as well as the large volume expansion and contraction during charging and discharging, have made it impossible to commercialize it so far. [0003] A more commonly used method is to combine sulfur with nano-inorganic metals. It is hoped that the high specific surface area of ​​nano-inorganic metals can be used to achieve the adsorption of sulfur and improve the co...

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Problems solved by technology

However, the conductivity of elemental sulfur is weak, and the dissolution of polysulfides in the electrolyte, as well as the large volume expansion and contraction during charging and discharging, have made it impossible to commercialize it so far.

[0003] A more commonly used method is to combine sulfur with nano-inorganic metals. It is hoped that the high specific surface area of ​​nano-inorganic metals can be used to achieve the adsorption of sulfur and improve the conductivity of sulfur. The disadvantage of this method is that the sulfur content of the electrode is greatly reduced. The current carrying capacity is less than 50%, which cannot reflect the superiority of lithium-sulfur batteries;

However, it still fails to completely solve the problem of sulfur dissolution

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