Binder for lithium-sulfur battery cathode and its application in the preparation of lithium-sulfur battery

Abstract

The invention belongs to the field of battery adhesives and provides an adhesive for an anode of a lithium sulfur battery. The adhesive consists of 50 to 95 wt% of gelatinized starch and 5 to 50 wt% of an additive, wherein the additive is at least one of carboxymethyl cellulose sodium and polyvinyl alcohol. The invention also provides application of the adhesive to preparation of the lithium sulfur battery. When the adhesive is applied to preparation of the lithium sulfur battery, the cycling performance of the lithium sulfur battery can be greatly improved.

Description

technical field [0001] The invention belongs to the field of battery binders, in particular to a binder for positive electrodes of lithium-sulfur batteries and its application in the preparation of lithium-sulfur batteries. Background technique [0002] With the vigorous development of the consumer electronics market, the power consumption of consumer mobile electronic devices such as mobile phones and laptops continues to increase, as well as consumers' preference for thin and light electronic products, all of which put forward higher requirements for the energy density of lithium batteries . However, the energy density of traditional lithium-ion batteries has been difficult to be greatly improved. In this case, lithium-sulfur batteries with high theoretical energy density have attracted widespread attention. Lithium-sulfur batteries usually use elemental sulfur or other sulfur-containing active materials as the positive electrode active material, use ether solvents or ion...

AI Technical Summary

Problems solved by technology

Although lithium-sulfur batteries have advantages in energy density, and their theoretical energy density can reach up to 2600Wh / kg, their cycle decay is too fast to meet the needs of commercial applications.

[0003] Since the positive electrode of general lithium-sulfur batteries still uses polyvinylidene fluoride, a commercial lithium-sulfur battery positive electrode binder, this binder swells severely in the ether electrolyte used in lithium-sulfur batteries, and the bonding performance is easy to decline, resulting in the lithium-sulfur battery positive electrode Larger capacity decay during cycling

At the same time, the price of polyvinylidene fluoride is relatively high, and using it as a positive electrode binder will lead to high production costs for lithium-sulfur batteries

When using polyvinylidene fluoride, it is generally necessary to use expensive organic solvents such as N-methylpyrrolidone to dissolve it. N-methylpyrrolidone has a high boiling point, which leads to high drying temperature and long drying time of the electrode sheet, which is easy to make The elemental sulfur in the electrode sheet volatilizes to cause capacity loss

In addition, N-methylpyrrolidone also has certain toxicity, its median lethal dose in rats is 3.8mL / kg, long-term inhalation can cause central nervous system dysfunction

[0004] Some researchers have used a mixture of hydroxymethyl cellulose and styrene-butadiene rubber or animal gelatin as the positive electrode binder, which has improved the cycle performance of lithium-sulfur batteries to a certain extent, but the number of cycles is still less than 100, which is difficult to compete with commercial lithium-ion batteries. batteries compete

In addition, because styrene-butadiene rubber contains more active carbon-carbon double bonds, it is easy to react with the intermediate products of lithium-sulfur battery electrodes, while animal gelatin is more sensitive to acid, alkali, enzyme, heat, etc. It is hydrolyzed into low-molecular-weight polypeptides, so it is necessary to develop a positive electrode binder for lithium-sulfur batteries with better performance

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