Metal atom-doped porous carbon nano composite material as well as a preparation method and application thereof

Abstract

The invention relates to a metal atom-doped porous carbon nano composite material, as well as the preparation method and the application of the metal atom-doped porous carbon nano composite material,which belongs to the technical field of lithium-sulfur batteries. The composite material comprises a porous carbon nano material matrix and metal atoms loaded on the porous carbon nano material matrix. The metal is doped in an atomic form, so that the adsorption of a host material to polysulfide can be improved. The shuttle effect of polysulfide is weakened. The composite material is used as a positive electrode material of a lithium-sulfur battery. Compared with the prior art, the lithium-sulfur battery has the advantages that the discharge rate of the battery can be improved. The excellent cycle life can still be kept during high-power discharging. The charge-discharge specific capacity and coulombic efficiency of the lithium-sulfur battery and the cycle stability of the battery are greatly improved. The purpose of manufacturing the high-power, high-capacity and long-service-life lithium-sulfur battery is achieved. In the method, the carbon source and the metal salt are wide in source and low in price. The preparation method is simple, convenient, environment-friendly, pollution-free and suitable for industrial production.

Description

technical field [0001] The invention belongs to the technical field of lithium-sulfur batteries, and in particular relates to a metal atom-doped porous carbon nanocomposite material and its preparation method and application. Background technique [0002] Sulfur exists widely in nature, and the data show that the abundance of sulfur in nature is about 0.048wt%, and it is a natural resource that has not been fully utilized. Sulfur in nature is mainly elemental sulfur (S 8 ) form, and its basic physical properties make researchers excited about the application of sulfur in lithium batteries. Elemental sulfur has the characteristics of low toxicity, low price, large storage capacity and low density. In particular, Li / S batteries have a high theoretical energy density. The specific capacity of elemental sulfur is as high as 1,675mAh / g, and the mass specific energy is as high as 2,600Wh / kg. , is the cathode material with the highest specific capacity known so far. [0003] Hig...

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Problems solved by technology

[0003] High specific capacity and energy density mean that the weight and volume of lithium-sulfur batteries are small and the discharge capacity is strong. Compared with the mature lithium-ion batteries today, they can better meet the needs of the development of electric vehicles today. However, the research and development of lithium-sulfur batteries Many problems have also been encountered, including: (1) The metal lithium negative electrode reacts with the polysulfide dissolved in the electrolyte, resulting in loss and erosion of the positive active material, which eventually causes the structure of the positive electrode region to collapse, and because the metal lithium and polysulfide The reaction of the lithium-sulfur battery will also lead to the passivation and corrosion of the metal lithium negative electrode, consume the electrolyte and metal lithium, resulting in extremely poor rate performance of the battery; (2) During the discharge process of the lithium-sulfur battery, the formed polysulfides , the shuttle effect is intensified and the polysulfides dissolved in the electrolyte cause the viscosity of the electrolyte to increase, the conductivity to decrease, the battery performance to decrease significantly, and the Coulombic efficiency to be lower than 100%; (3) The operating temperature of the lithium-sulfur battery system is as high as 300 ~ 400°C, which requires more expensive high-temperature-resistant materials and complex preparation processes to prevent the battery from burning

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