COMPOSITE POSITIVE MATERIAL FOR LITHIUM-SULPHUR BATTERY WITH HIGH RATE PERFORMANCE AND PREPARATION METHOD

摘要

A composite positive material for a lithium-sulphur battery with high rate performance consisting of a conductive agent, an electrochemical active substance and a modifier, wherein the conductive agent is a mesoporous carbon material, the electrochemical active substance is dispersed in holes of the mesoporous carbon material, and the modifier is introduced by means of chemical bonding to adjust the properties of the holes, so that lithium ions freely pass through while the passing of polysulphide ions is inhibited. With respect to the composite positive material, by means of the characteristic of selective passing of ions, efficient moving in and out of the lithium ions in the positive material can be guaranteed, meanwhile, lithium polysulphide is effectively inhibited from overflowing from the holes of the mesoporous carbon material in a charge-discharge process, and the dissolution of lithium polysulphide in an electrolyte solution is inhibited. Therefore, the composite positive material can not only have excellent high rate performance but also can effectively reduce the influences of active substance loss as well as lithium negative corrosion, fast capacity fading and the like caused by a "shuttling effect" because of lithium polysulphide dissolution, and the cycle performance of the lithium-sulphur battery is remarkably improved.