Porous carbon sphere-encapsulated vanadium oxide heterogeneous core-shell sphere structure material and preparation method, lithium-sulfur battery separator and lithium-sulfur battery

Abstract

The invention belongs to the field of electrochemical materials, and provides a porous carbon sphere-encapsulated vanadium oxide heterogeneous core-shell sphere structure material and a preparation method, a lithium-sulfur battery separator, and a lithium-sulfur battery. The preparation method of porous carbon sphere-encapsulated vanadium oxide heterogeneous core-shell sphere structure material is to stir and react water, ethanol, ammonia water, tetraethyl orthosilicate, resorcinol and formaldehyde to obtain a carbon-coated silica core-shell structure After carbonization treatment, add it to sodium hydroxide solution to obtain hollow porous carbon spheres, mix ammonium metavanadate, ethanol and nitric acid to obtain vanadium oxide solution, add hollow porous carbon spheres, and hydrothermally react after ultrasonic treatment to obtain product. By adjusting the ultrasonic time to control the amount of vanadium oxide precursor entering the interior of the porous carbon spheres, the artificial controllability of the nanostructure is realized. The product uses non-polar carbon spheres as the surface layer, which has adsorption effect on polysulfides, and the inner layer has High conversion efficiencies are exhibited when sulfur is present.

Description

technical field [0001] The invention belongs to the field of electrochemical materials, and in particular relates to a porous carbon ball-encapsulated vanadium oxide heterogeneous core-shell ball structure material and a preparation method, a lithium-sulfur battery separator and a lithium-sulfur battery. Background technique [0002] Lithium-sulfur batteries have high theoretical energy density (2600Wh kg-1) and specific capacity (1675mAh g-1), in addition, sulfur has low toxicity and environmental friendliness, and is cheap, so lithium-sulfur batteries are considered to be the most promising. next-generation energy storage systems. However, lithium-sulfur batteries also have the following problems: First, due to uneven lithium deposition, lithium dendrites will form during the cycle, resulting in the damage, deactivation of the lithium anode, or even becoming "dead lithium", which greatly increases the electrolyte concentration. consumption, reducing the reversibility of t...

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Problems solved by technology

However, lithium-sulfur batteries also have the following problems: First, due to uneven lithium deposition, lithium dendrites will be formed during the cycle, resulting in damage, deactivation or even "dead lithium" of the lithium anode, which greatly increases the concentration of the electrolyte. Consumption, reducing the electrolyte and the reversibility of the lithium anode

In addition, the sharp Li dendrites can pierce the separator leading to short circuits and thermal runaway.

Second, the volume expansion during charging and discharging is large (~79%), resulting in easy damage to the structure

The third is that the sulfur cathode will generate soluble lithium polysulfides (LiPSs) during charge and discharge, and its conductivity is low.

[0004] At present, one of the functional modification methods of the separator is to use porous materials to modify the separator, such as porous carbon, but most of these conductive materials are non-polar, and the adsorption of polysulfides is mainly physical adsorption, and the Coulombic efficiency is low.

The second is to use elements doped (such as N) carbon, sulfide and other materials to modify the separator, so that the separator has a strong chemical adsorption capacity, which can effectively capture LiPSs in the electrolyte, but the amount of LiPSs adsorbed and captured is different from that of the modified materials. Therefore, the more the amount of LiPSs adsorbed and captured, the thicker the thickness of the separator modification layer will seriously affect the diffusion of ions, thus greatly reducing the rate performance.

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