Cross-linked Aqueous Binder for Lithium Sulfur Battery Electrodes
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Solution Overview
Problem
Lithium sulfur batteries face challenges in maintaining the structure of sulfur/carbon charge/discharge composites due to low adhesiveness between the electrode and composite, resulting in low areal electrode loading and insufficient suppression of lithium-polysulfide elution, which affects the battery's initial coulombic efficiency and lifespan.
Innovation Solution
Incorporating a cross-linker during the manufacture of lithium secondary battery electrodes to enhance the physical properties of the aqueous binder, specifically using compounds represented by Formulas 1 and 2, which crosslink the binder, improving adhesion and stability, thereby increasing the area capacity and lifespan of the battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional aqueous binders are used in lithium sulfur batteries, then the manufacturing process is simple, but the adhesion between electrode and sulfur/carbon composite is insufficient, resulting in low areal electrode loading
Solution Approach 1:
The cross-linker is incorporated into the aqueous binder preparation process before electrode assembly, allowing the cross-linking reaction to occur during binder formation. This preliminary action ensures that the binder already possesses enhanced adhesive properties when applied to the sulfur/carbon composite, thereby improving adhesion without requiring additional processing steps after electrode assembly.
Solution Approach 2:
The invention modifies the chemical parameters of the aqueous binder by introducing cross-linking agents that form covalent bonds with the binder polymers. This parameter change transforms the binder from a simple adhesive to a chemically cross-linked network structure, significantly enhancing its bonding strength to the sulfur/carbon composite while maintaining process simplicity.
2Reliability
If conventional aqueous binders are used, then the manufacturing process is straightforward, but the suppression of lithium-polysulfide elution is insufficient, affecting initial coulombic efficiency
Solution Approach 1:
The invention creates a composite binder system by combining conventional aqueous binder polymers with cross-linking agents. This composite material approach allows the binder to simultaneously provide mechanical adhesion and chemical suppression of lithium-polysulfide elution through the cross-linked network structure, maintaining ease of manufacture while improving reliability.
3Quantity of substance
If conventional aqueous binders are used, then the electrode structure is simple, but the area capacity is limited due to insufficient adhesion and charge retention
Solution Approach 1:
The cross-linking structure is established in the binder before electrode assembly, creating a pre-reinforced binding matrix. This preliminary structural reinforcement allows the electrode to maintain its composition stability during subsequent charge/discharge cycles, enabling higher area capacity without compromising structural integrity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The cross-linked aqueous binder enhances the initial coulombic efficiency and lifespan of lithium sulfur batteries by improving the physical properties, leading to higher area capacity and better charge retention, as demonstrated in comparative cycle and efficiency tests.
Implementation Method 1
a cross-linker which crosslinks the aqueous binder
Data Source
Figure 1
Figure 2
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AI summary
The present invention relates to an electrode for a lithium secondary battery, a method for preparing the same, an electrode assembly for a lithium secondary battery comprising the same, and a lithium secondary battery comprising the same, wherein the electrode comprises an electrode active material, an aqueous binder, a compound represented by Formula 1, and a compound represented by Formula 2. Formula 1 and Formula 2 are the same as set forth in the specification. The electrode for a lithium secondary battery improves the physical properties of the aqueous binder in a manner whereby a cross-linking reaction material is combined with the aqueous binder, so that the electrode can improve initial charge/discharge efficiency and the life span of a lithium secondary battery, preferably a lithium sulfur battery, and improve the area capacity of the electrode.