Nano-rod porous carbon-sulfur composite cathode material, preparation method thereof and lithium-sulfur battery

Abstract

The invention discloses a preparation method of a nano-rod porous carbon-sulfur composite cathode material. The preparation method comprises the steps of mixing a zinc nitrate hexahydrate solution with 4,4'-biphenyl dicarboxylic acid disodium salts at a normal temperature; then centrifugally washing and drying the mixture to obtain a zinc-based metal organic framework precursor; roasting the precursor in inert gas atmosphere; mixing obtained nano-rod porous carbon with elemental sulfur; ball-grinding and drying the mixture and then carrying out thermal treatment so as to obtain the nano-rod porous carbon-sulfur composite cathode material. The prepared nano-rod porous carbon-sulfur composite cathode material is a composite material of the nano-rod porous carbon and the elemental sulfur and has the pore diameter of 1 nm-3 nm, and the elemental sulfur is located in the pore passages of the nano-rod porous carbon. The material is low in preparation cost and small in pore diameter, has the strong binding effect on the polysulfide, can effectively inhibit the shuttling effect and improve the electrochemical performance of the battery.

Description

technical field [0001] The invention relates to the technical field of lithium-ion batteries, in particular to a nanorod porous carbon-sulfur composite cathode material, a preparation method thereof, and a lithium-sulfur battery. Background technique [0002] At present, commercial lithium-ion batteries can no longer meet the specific capacity and specific energy requirements of electric vehicles and other products for power batteries. As a new type of electrochemical energy storage system, lithium-sulfur (Li-S) battery has a theoretical specific energy of up to 2600Wh / kg. As a positive electrode material, sulfur has a theoretical specific capacity of more than 1600mAh / g, and sulfur has abundant reserves and low price. , Environmental friendliness and other advantages, has a very high application value. However, there are still many problems to be solved in order to realize the practical application of lithium-sulfur batteries. First of all, sulfur is an insulator, and a c...

AI Technical Summary

Problems solved by technology

The porous structure, good conductivity and mechanical properties of carbon materials have better solved the problems of poor conductivity and volume expansion of sulfur electrodes, but the shuttle effect of polysulfides is still not well resolved.

Theory proves that when the pore size is small enough (about 1nm), the porous carbon material will have a strong binding effect on polysulfides, thereby increasing the utilization rate of sulfur and reducing the shuttle effect of polysulfides. The pore diameter of some porous carbons is more than 10nm, and polysulfides cannot be completely bound in the positive electrode area. Therefore, how to effectively synthesize porous carbons with small pore diameters is an urgent technical problem for those skilled in the art.

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