Method for preparing lithium sulfide by using metallic lithium

A method for preparing lithium sulfide by using metallic lithium, comprising the following steps:

• step A:
• placing 0.05-0.1 kg of the metallic lithium and a first sulfur powder into a 5-10 L sealed container under an inert condition according to a mass ratio of the metallic lithium to the first sulfur powder being 1:0.8-1:1;
• step B:
• placing the 5-10 L sealed container charged with the first metallic lithium and the first sulfur powder in step A into a vacuum oven at 250-300° C. and holding for 2-3 h, then adding a second sulfur powder at an amount equal to an amount of the first sulfur powder into the vacuum oven and heating at 250-300° C. for 2-3 h, and finally adding a third sulfur powder at an amount equal to the amount of the first sulfur powder into the vacuum oven and heating at 250-300° C. for 2-3 h to obtain a crude lithium sulfide product;
• step C:
• placing the crude lithium sulfide product into a sealed ball-milling tank, and performing ball-milling at room temperature at a rotation speed of 100-500 r/min for 12-24 h to obtain a ball-milled lithium sulfide;
• step D:
• under an inert gas, taking out the ball-milled lithium sulfide from the ball-milling tank, then adding the ball-milled lithium sulfide into a mixed solution of isopropanol and xylene with a mass-to-volume ratio of the ball-milled lithium sulfide to the mixed solution being 1:5, and stirring for 1-2 h to obtain a lithium sulfide slurry;
• step E:
• under the inert gas, filtering the lithium sulfide slurry with a G4 sand core funnel, and then rinsing with 500-1000 mL of n-hexane to obtain a lithium sulfide wet material;
• and
• step F:
• placing the lithium sulfide wet material into a vacuum drying oven at 205° C., and drying in vacuum for 8-12 h to obtain a lithium sulfide product.