Preparation method of sulfur positive electrode composite material based on high-energy density type graphene

Abstract

The invention discloses a preparation method of a sulfur positive electrode composite material based on high-energy density type graphene, which comprises the following steps: adding graphite powder, sodium nitrate and potassium permanganate into concentrated sulfuric acid, and stirring to slowly heat; after the solution is reacted and heated, adding deionized water and a reducing agent, filtering and drying to obtain graphite oxide; the preparation method comprises the following steps: performing ultrasonic treatment on graphite oxide to obtain a dispersion liquid A, heating to 80-90 DEG C, adding hydrazine hydrate, filtering, washing and drying to obtain graphene oxide; adding water into graphene oxide, and performing ultrasonic treatment to obtain dispersion liquid B; adding water into inorganic sulfide, stirring and dissolving to obtain a sulfur solution C; and mixing the dispersion liquid B and the sulfur solution C until the reaction is complete, adding dilute acid to adjust the solution to be acidic, filtering and drying to obtain the graphene / sulfur positive electrode composite material, the capacity is 1186 mAh.g <-1 > under the charging condition of 0.1 DEG C, the coulombic efficiency is 96% after 200 times of circulation, the capacity is 997 mAh.g <-1 > under the charging condition of 1 DEG C, and the capacity is 578 mAh.g <-1 > after 1000 times of circulation.

Description

technical field [0001] The invention relates to the field of lithium battery preparation, in particular to a preparation method based on a high energy density graphene-sulfur cathode composite material. Background technique [0002] Compared with traditional secondary batteries, lithium batteries have higher volume specific energy and mass specific energy, which can make batteries smaller and lighter, and are relatively energy-saving and environmentally friendly. However, the energy density of lithium batteries currently commercially used is low, generally only 150-200Wh / kg, which has become one of the bottlenecks in the application of high energy-consuming technologies. The sulfur cathode in lithium-sulfur batteries can provide a theoretical specific capacity of up to 1675mAh / g (more than five times the capacity of conventional LiCoO2 cathodes), and the lithium-sulfur electrochemical pair has an energy density of 2600Wh / kg (higher than that of conventional lithium-ion batte...

AI Technical Summary

Problems solved by technology

[0003] Graphene is an ideal candidate material for use as a high-performance composite material reinforcement. By using sulfur and graphene composite materials for the production of lithium cathodes, it can solve the problem of dissolution of lithium battery charging and discharging intermediate products and improve battery cycle performance. However, the current graphene / sulfur cathode composite materials also have the problems of complex preparation process and uneven composite.