▎ 摘　　要

NOVELTY - A solution prepared using chromium nitrate nonahydrate, 2-hydroxyterephthalic acid, deionized water, and hydrofluoric acid is heated for hydrothermal reaction. The obtained crystals are washed with water, dimethylformamide and ethanol, centrifuged, filtered, and dried to obtain MIL-101(Cr) metal-organic frame material. The frame material and sulfur are ball-milled and heated to obtain a MIL-101(Cr)-S composite. Graphene and the obtained composite are ball-milled and dried to obtain a metal-organic framework (MIL-101(Cr))/graphene composite. USE - Melt-diffusion preparation of metal-organic framework (MIL-101(Cr))/graphene composite for positive-electrode active materials of lithium-sulfur batteries. ADVANTAGE - The method enables uniform diffusion of sulfur in the frame material. The obtained composite has high specific surface area and pore volume, and excellent conductivity, power performance, and coulomb efficiency. The discharging specific capacity of the composite is 1087 mAh/g at 0.1 C, 807 mAh/g at 0.8 C, and 387 mAh/g at 2.4 C. The method is simple, convenient, and suitable for large-scale industrial production. DETAILED DESCRIPTION - Chromium nitrate nonahydrate (2-2.4 g) and 2-hydroxyterephthalic acid (0.833-0.996 g) are dissolved in deionized water (30-50 mL), and hydrofluoric acid (0.26-0.3 mL) is added. The obtained solution is transferred to a 50-100-mL PTFE reaction tank, which is placed in a stainless steel outer sleeve, sealed, and heated in a furnace for hydrothermal reaction. The temperature program involves increasing the temperature to 5-10 degrees C/minute from room temperature to 210-220 degrees C, maintaining for 8-10 hours, and cooling to room temperature at 6 degrees C/minute. The obtained crystals are washed with water, dimethylformamide and ethanol, centrifuged, filtered, and dried to obtain MIL-101(Cr) metal-organic frame material. The metal-organic frame material and sulfur are ball-milled in a weight ratio of 1.6-3.2 and heat-treated in a temperature-programmed furnace to obtain a MIL-101(Cr)-S composite. Graphene and the obtained composite are ball-milled in a weight ratio of 1:(2-10) and dried at 150-200 degrees C to obtain a metal-organic framework (MIL-101(Cr))/graphene composite.