Sulfur-carbon composite material with nitrogen-doped porous carbon nanofiber net-shaped structure, as well as preparation method and application of composite material

Abstract

The invention belongs to the technical field of lithium sulfur batteries, specifically relates to a sulfur-carbon composite material with a nitrogen-doped porous carbon nanofiber net-shaped structure, as well as a preparation method and an application of the composite material. By taking a polypyrrole net-shaped structure which is synthesized by virtue of a soft template method as a raw material, taking the potassium hydroxide as a pore forming agent, and taking the nitrogen-doped carbon nanofiber net-shaped structure which is synthesized through high-temperature carbonization under nitrogen atmosphere and is in a porous structure as a precursor, the sulphur-carbon composite material which can be used as the anode of the lithium sulfur battery can be prepared through heat treatment with elemental sulfur. The preparation method provided by the invention is simple, and good in reproducibility, and the prepared composite material is uniform in structure distribution, and can be used as the anode of the lithium sulfur battery. Due to the nitrogen doping and the tridimensional net-shaped structure, for the material, the conductivity can be improved, a transmission path of lithium ions is shortened, meanwhile, the dissolving of the sulfur and intermediate product in an electrolyte can be prevented, the electrochemistry performance of a positive material of the lithium sulfur battery is improved, good specific discharge capacity, cycle performance and rate performance can be achieved.

Description

technical field [0001] The invention belongs to the technical field of lithium-sulfur batteries, and in particular relates to a lithium-sulfur battery cathode material and a preparation method and application thereof. Background technique [0002] Lithium-sulfur battery, using elemental sulfur (or sulfur-containing compound) as the positive electrode, metal lithium as the negative electrode, a type of metal lithium secondary battery that realizes the mutual conversion between chemical energy and electrical energy through the chemical reaction between sulfur and lithium, its theoretical ratio Capacity is 1675 mAh g -1 , the theoretical energy density is 2600 Wh kg -1 , the actual energy density can reach 300 Wh kg -1 , it is very likely to increase to 600 Wh kg in the next few years -1 About, compared with traditional lithium ion battery oxide electrode materials, such as lithium cobalt oxide, lithium manganese oxide, and lithium iron phosphate, sulfur-based cathode materi...

AI Technical Summary

Problems solved by technology

[0003] But at present, the development and application of lithium-sulfur batteries are limited by many aspects, one of which is the influence of cathode materials

The conductivity of sulfur is low (5x 10-30S / cm), and the polysulfides produced by the cathode material of lithium-sulfur batteries during the discharge process are easily soluble in the organic electrolyte, which not only causes lithium-sulfur The battery has low active material utilization, and the dissolved polysulfides will migrate to the negative electrode and be reduced to insoluble Li2S2 / Li 2S is deposited on the negative electrode lithium, which greatly damages the electrode structure, resulting in a large decline in battery capacity and poor cycle performance [J.H. Shin, E.J. Cairns, J. Electrochem. Soc. 155 (2008) A368– A373], thus limiting its further development and application

Images