Novel carbon-sulfur compound for lithium-sulfur battery

Abstract

The invention relates to a novel carbon-sulfur compound for an anode material of a lithium-sulfur battery and a preparation method thereof. Sulfur is filled into a nano and micron hole of a matrix in an elementary substance way by taking a macroporous carbon material with high pore volume, electrical conductivity and specific surface area as the matrix, and the sulfur and carbon can also carry out combination reaction so as to prepare the novel carbon-sulfur compound of which the sulfur exists in one or more chemical states in a carbon material. The novel carbon-sulfur compound used as the anode material of the lithium-sulfur battery has the advantages that the high pore volume has large contained sulfur contents and can ensure high electric capacity; the small granularity of the sulfur can reduce a conductive distance between ions and electrons and increase the utilization ratio of the sulfur; and the adsorption characteristics of the high specific surface of the carbon material can inhibit a discharging intermediate product from dissolving and moving towards a cathode, reduce the self discharge, prevent a nonconductive discharging product, namely lithium sulfide from largely accumulating outside carbon particles and reduce internal resistance, therefore, the material can improve the specific energy, the specific power and the cycle performance of the lithium-sulfur battery.

Description

technical field [0001] The invention relates to a high specific energy lithium battery sulfur-containing cathode material and a preparation method thereof. Background technique [0002] The theoretical specific capacity of elemental sulfur is 1675mAh / g, and the theoretical specific energy of a battery composed of lithium can reach 2600Wh / kg. It is a high specific energy battery material. In addition, it also has the advantages of low cost and low toxicity. Therefore, lithium sulfur batteries The system has received attention as early as the 1970s and 1980s. R.D.Rauh et al. believe that the lithium polysulfide dissolved in the electrolyte does not affect the stability of lithium metal, and has the possibility of making a secondary battery (J. Electrochem. Soc. 1979, 126(4): 523-527). Yamin and Peled studied the electrochemical reaction mechanism of lithium polysulfide, and believed that the process of reducing it to low-level sulfide is very complicated, including not only t...

AI Technical Summary

Problems solved by technology

The main problem in the lithium-sulfur battery system is that the insulation of sulfur leads to low utilization of the material, and the cycle capacity decays seriously. The first reason is that the Li generated during the discharge process 2 S X (22 S 2 with Li 2 The electrical insulating layer of S causes the gradual isolation between the conductive agent particles and the current collector, which eventually leads to capacity decay; the third is "Li 2 S X Shuttle effect” (Li generated by charging on the positive electrode 2 S X It dissolves and diffuses to the negative electrode, undergoes a self-discharge reaction with lithium, and the self-discharged product migrates back to the positive electrode, and is charged and oxidized to Li 2 S X ) results in low charge and discharge efficiency, and it is even difficult to determine the charging end point