Lithium-sulfur battery, preparation method thereof and positive electrode material

Abstract

The present invention relates to a lithium-sulfur battery, a preparation method thereof and a positive electrode material. The binder comprises a polymer that is composed of a structural unit shown inthe formula (1) and a solution of carboxylic acid compounds with a polyalkenyl structure. The preparation method of the lithium-sulfur battery binder is also provided. The present invention also relates to the positive electrode material of the lithium-sulfur battery comprising the above lithium-sulfur battery binder. The technical solution of the invention binds polysulfide ions in the positiveelectrode and effectively suppresses the dissolution loss by providing the lithium-sulfur battery binder capable of reducing dissolution and shuttle of polysulfide ions, effectively adsorbs the polysulfide and improves the ion conduction efficiency. Meanwhile, preferable mechanical property is realized through the network cross-linking structure and the chemical interaction between sulfonic acid groups and polysulfide, and the effects of stabilizing the electrode structure and resisting the volume change during charge and discharge of the electrode are realized.

Description

technical field [0001] The invention belongs to the field of battery binders, and in particular relates to a lithium-sulfur battery binder, a positive electrode material and a preparation method thereof. Background technique [0002] Due to its high theoretical energy density and other advantages, lithium-sulfur batteries are considered to be a potential next-generation high-energy battery system and have become a research hotspot all over the world. Lithium-sulfur batteries generally use elemental sulfur as the positive electrode active material, metallic lithium as the negative electrode, and an organic liquid electrolyte for the secondary battery system. Studies have found that when elemental sulfur undergoes redox reactions, double electrons are gained and lost. The capacity reaches 1672mAh·g -1 , the theoretical specific energy of the lithium-sulfur battery composed of metal lithium is as high as 2500Wh·kg -1 . In addition, elemental sulfur is abundant in nature, che...

AI Technical Summary

Problems solved by technology

The bonding performance of the binder in the prior art is insufficient, which causes the active material to fall off easily during the preparation of the electrode sheet, and the utilization rate of the sulfur active material is reduced; secondly, the existing binder generally swells seriously in the ether electrolyte, Its bonding performance is further reduced, leading to rapid decay of battery capacity; in addition, in the use of these binders, it is necessary to use expensive and environmentally harmful organic solvents such as N-methylpyrrolidone (NMP), and this Organic solvents have a high boiling point, which leads to high drying temperature and long drying time of the electrode sheet, which reduces the production efficiency of the battery

[0005] The binders in the prior art are insufficient in inhibiting the polysulfide shuttle effect, and cannot effectively inhibit the dissolution loss, resulting in the active material falling off easily during the preparation of the electrode sheet, and the utilization rate of the sulfur active material is reduced; secondly, the existing binder Generally, the swelling phenomenon in the ether electrolyte is serious, and it cannot effectively resist the volume change during the charging and discharging process of the electrode, resulting in a rapid decline in battery capacity; in addition, in the use of these binders, N-methylpyrrolidone (NMP ) and other organic solvents that are expensive and harmful to the environment, and such organic solvents have a high boiling point, resulting in high drying temperature and long drying time of the electrode sheet, which reduces the production efficiency of the battery

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