Lithium-sulfur battery modified diaphragm and preparation method thereof

Abstract

The invention provides a lithium-sulfur battery modified diaphragm and a preparation method thereof, the modified diaphragm comprises a diaphragm matrix, the surface of the diaphragm matrix is coated with a conductive coating, and the conductive coating comprises a conductive skeleton and a polysulfide adsorbent and a catalyst loaded on the conductive skeleton; and the conductive skeleton is mainly prepared from a zero-dimensional conductive carbon material, a one-dimensional conductive carbon material and a two-dimensional conductive carbon material, and has a microporous structure. The preparation method comprises the following steps: uniformly mixing a polysulfide adsorbent, a zero-dimensional conductive carbon material, a one-dimensional conductive carbon material, a two-dimensional conductive carbon material, a catalyst, a high-molecular polymer, pure water and a polar organic solvent to obtain modified diaphragm slurry, coating a diaphragm substrate with the modified diaphragm slurry to obtain a coated diaphragm, transferring the coated diaphragm into pure water, and drying the coating diaphragm from which the solvent is removed. According to the modified diaphragm for the lithium-sulfur battery, the migration path of polysulfide can be prolonged, shuttling of the polysulfide in the diaphragm for the lithium-sulfur battery can be effectively inhibited, and the cycle performance of the lithium-sulfur battery is improved.

Description

technical field [0001] The invention belongs to the technical field of new energy materials and devices, and in particular relates to a modified separator for a lithium-sulfur battery and a preparation method thereof. Background technique [0002] Due to the rich source of raw materials, the lithium-sulfur battery is cheap, and it also has a high theoretical energy density (1675mAh g -1 ), energy density (2600Wh Kg -1 ), considered to be the most likely secondary battery to replace lithium-ion batteries. However, polysulfides that can be dissolved in the electrolyte are inevitably generated during the charging and discharging of lithium-sulfur batteries. The dissolved polysulfide diffuses to the lithium anode through the separator and undergoes side reactions with metallic lithium, leading to the loss of active materials and corrosion of metallic lithium, which significantly reduces the charge-discharge capacity, rate performance, and cycle life of lithium-sulfur batteries...

AI Technical Summary

Problems solved by technology

In theory, reducing the pore size of the separator can completely block polysulfides, but it also greatly reduces the ionic conductivity of the separator and reduces the rate performance of the battery.

Coating materials with the ability to adsorb polysulfides can adsorb polysulfides. The coating reduces the ability of polysulfides to shuttle to a certain extent, but the adsorption capacity of coating materials for polysulfides is limited, and the dense coating The layer also reduces the ionic conductivity of the separator to a certain extent, and the inhibition effect on the shuttle effect is not obvious.

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