JP-2026514296-A - Polymer binders for hydroxyl group-based or carboxylic acid-based sulfur batteries and sulfur batteries containing the same

JP2026514296AJP 2026514296 AJP2026514296 AJP 2026514296AJP-2026514296-A

Abstract

The present invention relates to a polymer binder for hydroxyl-based sulfur batteries that can effectively suppress the elution of polysulfide, which is generated by the reduction of sulfur during the discharge process, into the electrolyte, thereby solving the problem of reduced lifespan characteristics of sulfur batteries, a positive electrode for sulfur batteries containing the same, and a sulfur battery. The polymer binder for sulfur batteries according to one embodiment of the present invention is characterized by being produced by a chemical reaction between a water-soluble polymer and a hydroxyl-based crosslinking agent represented by the formula M(OH) n (wherein the formula, M is a metal or quasi-metallic, and n is an integer from 1 to 5). The present invention also relates to a polymer binder for carboxylic acid-based sulfur batteries that can effectively suppress the elution of polysulfide, which is generated by the reduction of sulfur during the discharge process, into the electrolyte, thereby solving the problem of reduced lifespan characteristics of sulfur batteries, a positive electrode for sulfur batteries containing the same, and a sulfur battery. The polymer binder for sulfur batteries according to one embodiment of the present invention is a crosslinked water-soluble polymer binder produced by a chemical reaction between a water-soluble polymer and a carboxylic acid-based crosslinking agent.

Inventors

チョ，ギュボン
チョ，クォンク
ブーミレッディ，スリニヴァスラレッディ
アン，ジュヒョン
アン，ヒョジュン
ナム，テヒョン

Assignees

インダストリー－アカデミックコーオペレイションファウンデーションキョンサンナショナルユニバーシティ

Dates

Publication Date: 20260508
Application Date: 20240215
Priority Date: 20230220

Claims (16)

In a binder applied to a sulfur battery containing sulfur as the positive electrode active material, A crosslinked water-soluble polymer binder, characterized by being produced by a chemical reaction between a water-soluble polymer and a hydroxyl group-based crosslinking agent represented by the formula M(OH) n (wherein M is a metal or quasi-metallic, and n is an integer from 1 to 5).
The crosslinked water-soluble polymer binder according to claim 1, characterized in that the water-soluble polymer is selected from the group consisting of polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), carboxymethylcellulose (CMC), styrene-butadiene rubber (SBR), and combinations thereof.
The crosslinked water-soluble polymer binder according to claim 1, characterized in that in the formula M(OH) n , M is selected from the group consisting of sodium (Na), potassium (K), copper (Cu), cobalt (Co), calcium (Ca), nickel (Ni), boron (B), zirconium (Zr), aluminum (Al), silicon (Si), lithium (Li), radium (Ra), tantalum (Ta), tungsten (W), molybdenum (Mo), vanadium (V), manganese (Mn), and combinations thereof.
The crosslinked water-soluble polymer binder according to claim 1, characterized in that the water-soluble polymer is polyvinyl alcohol (PVA), and the hydroxyl group crosslinking agent is boric acid.
The crosslinked water-soluble polymer binder according to claim 1, characterized in that the content of the hydroxyl group crosslinking agent is 0.1 to 1% by weight relative to the total weight of the water-soluble polymer and the hydroxyl group crosslinking agent.
In the positive electrode of a sulfur battery containing sulfur as the positive electrode active material, Positive electrode active material and, A positive electrode for a sulfur battery comprising a positive electrode active material layer containing a crosslinked water-soluble polymer binder according to any one of claims 1 to 5.
In a sulfur battery containing sulfur as the positive electrode active material, A lithium-sulfur battery comprising the positive electrode described in claim 6.
In a battery containing sulfur as the positive electrode active material, A sodium-sulfur battery comprising the positive electrode described in claim 6.
In a binder applied to a sulfur battery containing sulfur as the positive electrode active material, A cross-linked water-soluble polymer binder characterized by being produced by a chemical reaction between a water-soluble polymer and a carboxylic acid-based cross-linking agent.
The crosslinked water-soluble polymer binder according to claim 9, characterized in that the water-soluble polymer is selected from the group consisting of polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), carboxymethylcellulose (CMC), styrene-butadiene rubber (SBR), and combinations thereof.
The carboxylic acid-based crosslinking agents include tartaric acid ( C4H6O6 ) , fumaric acid ( C4H4O4 ), succinimide ( C4H5NO2 ) , malic acid ( C4H6O5 ), adipic acid ( C6H10O4 ) , malonic acid ( C3H4O4 ), acetylsalicylic acid ( C9H8O4 ) , and levulinic acid ( C5H8O3 ) . A crosslinked water-soluble polymer binder according to claim 9, characterized in that it is selected from the group consisting of ) and combinations thereof.
The crosslinked water-soluble polymer binder according to claim 9, characterized in that the water-soluble polymer is polyvinyl alcohol ( PVA ) and the carboxylic acid-based crosslinking agent is tartaric acid (C4H6O6 ) .
The crosslinked water-soluble polymer binder according to claim 9, characterized in that the content of the carboxylic acid-based crosslinking agent is 1 to 20% by weight relative to the total weight of the water-soluble polymer and the carboxylic acid-based crosslinking agent.
In the positive electrode of a sulfur battery containing sulfur as the positive electrode active material, Positive electrode active material and, A positive electrode for a sulfur battery comprising a positive electrode active material layer containing a crosslinked water-soluble polymer binder according to any one of claims 9 to 13.
In a sulfur battery containing sulfur as the positive electrode active material, A lithium-sulfur battery comprising the positive electrode described in claim 14.
In a battery containing sulfur as the positive electrode active material, A sodium-sulfur battery comprising the positive electrode described in claim 14.

Description

This invention relates to a binder applicable to sulfur batteries containing sulfur as a positive electrode active material, such as lithium-sulfur batteries or sodium-sulfur batteries. More specifically, it relates to a hydroxyl group-based or carboxylic acid-based polymer binder for sulfur batteries that can effectively suppress the elution of polysulfide into the electrolyte when sulfur is reduced during the discharge process, thereby solving the problem of reduced lifespan characteristics of sulfur batteries; a positive electrode for sulfur batteries containing the same; and a sulfur battery. Rechargeable batteries are used as a power source for many electronic devices. With the development of numerous standalone electronic devices, the range and importance of rechargeable batteries are increasing. In recent years, with the accelerated development of electric vehicles and energy storage, interest in high-capacity rechargeable batteries has grown. However, conventional lithium-ion batteries present many problems for use in electric vehicles and smart grid power storage applications. Firstly, lithium-ion batteries are expensive, and the cost of the secondary battery can account for over 70% of the total purchase price of an electric vehicle. Secondly, achieving high energy densities of 260 Wh/kg or more is difficult even when lithium-ion batteries are used in electric vehicles. Even with advancements in research and development, there are technical limitations to achieving an energy density of 300 Wh/kg with lithium-ion batteries containing conventional electrode materials. Therefore, to solve these problems, a new battery system capable of achieving low cost and high energy density is needed. One promising candidate is a sulfur battery, which uses sulfur as the main material for the positive electrode active material, such as lithium-sulfur batteries or sodium-sulfur batteries. Sulfur batteries can achieve a high energy density of 2600 Wh/kg per unit weight, which is approximately seven times that of lithium-ion batteries. Sulfur itself has advantages such as a small atomic weight, abundant resources, low cost, non-toxicity, and excellent environmental compatibility. For these reasons, it is being re-evaluated and attracting attention as a next-generation rechargeable battery. However, sulfur batteries also have drawbacks. These typically include significant volume expansion (approximately 80%) during the charge-discharge process and the leaching of polysulfides into the electrolyte during the discharge process. The latter, in particular, not only causes a large loss of active material weight but also leads to significant self-discharge, ultimately reducing the lifespan of the sulfur battery. Therefore, for the practical application of sulfur batteries, resolving the polysulfide leaching problem is a top priority. One way to solve these problems is to develop a novel binder that, in addition to binding the conductive material and the active material (sulfur) within the positive electrode, can also suppress volume expansion and polysulfide elution. However, conventional binders such as polyvinylidene fluoride (PVdF) are limited to binding the conductive material and the active material (sulfur), and have limitations in fulfilling all of the aforementioned roles. This is a schematic diagram showing a case in which a cross-linked water-soluble polymer binder (PVA-BA) according to one embodiment of the present invention is used as a binder in a lithium-sulfur battery.This is an FT-IR result graph related to Experimental Example 1.This is a graph showing the mechanical strength results for Experimental Example 2.This is a graph showing the results of the swelling degree and solubility experiment related to Experimental Example 3.This is a graph showing the results of the polysulfide adsorption experiment related to Experimental Example 4.This is a graph showing the results of the polysulfide adsorption experiment related to Experimental Example 4.This graph shows the results of testing the cycle characteristics of the battery related to Experimental Example 5 (charge/discharge rate of 0.2C).This is an FE-SEM image showing the electrode surface shape observed in Experimental Example 6.This schematic diagram shows a comparison between a lithium-sulfur battery in which polyvinyl alcohol (PVA) is used as the positive electrode binder and a case in which a cross-linked water-soluble polymer binder (PVA-TA) according to one embodiment of the present invention is used.This is a graph showing the results of Fourier transform infrared spectroscopy (FT-IR) for Experimental Example 1'.This is a graph showing the results of the swelling degree and solubility experiment related to Experimental Example 2'.This graph shows the results of testing the cycle characteristics of the battery related to Experimental Example 3' (charge/discharge rate of 0.5C).This graph shows the results of testing the cycle characteristics of the