The method of preparing a positive electrode for a lithium sulfur battery of sulfur

The invention provides a preparation method of a sulfur positive electrode of a lithium sulfur battery. The preparation method comprises the following steps: a) preparing a mixed slurry according to the condition that the mass ratio of a sublimed sulfur to an active carbon is (4-9):2; b) drying and grinding the mixed slurry; c) dispersing the mixture in a sodium bicarbonate or ammonia solution, and performing the ultrasonic oscillation; d) adding an aluminum sulfate, aluminum chloride or aluminum potassium sulfate solution according to the condition that the mol ratio of a sulfur carbon mixture to an aluminum element in aluminum salt is 100:(0.5-3) so as to prepare a composite material covered by the aluminum hydroxide; e) filtering and drying the composite material, warming to 140-300 DEG C within 6-11 hours under the protection of inert gas, and grinding to obtain the sulfur carbon positive electrode material covered by the aluminum oxide for the lithium sulfur battery; and f) preparing the positive electrode of the lithium sulfur battery, assembling and testing the performance of the battery. The initial discharging specific capacity of the sulfur positive electrode composite material for the lithium sulfur battery prepared by the invention can achieve 1441.7.8 mAh/g, the battery discharging specific capacity is still maintained at 808.1mAh/g at room temperature after ten times of circulation, and the capacity retention rate can achieve 56.52%.