Acrylic Resin Binder for High Temperature Battery Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium ion secondary batteries face challenges in maintaining high temperature durability and cycle performance due to the swelling of fluorine-based resins used as binders, leading to increased internal resistance and disconnected electron conduction networks.
Innovation Solution
A nonaqueous electrolyte secondary battery is developed with a negative electrode featuring a titanium-containing metal oxide and an acrylic resin binder, where the peel strength between the current collector and the mixed-material layer satisfies a specific ratio, ensuring excellent adhesion and maintaining electron conduction at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If fluorine-based resin (PVdF) is used as the binder for the negative electrode, then the negative electrode has good adhesion to the current collector, but the binder swells at high temperature causing network disconnection and increased internal resistance
Solution Approach 1:
The invention changes the chemical composition parameters of the binder by using acrylic resin with specific functional groups (carboxyl, hydroxyl, or amine groups) instead of conventional PVdF. This parameter change allows the binder to maintain stable physical and chemical properties at high temperatures, preventing the swelling and network disconnection that occurs with fluorine-based resins while retaining adequate adhesion to the current collector.
Solution Approach 2:
The invention employs a composite binder system consisting of acrylic resin as the primary binder combined with specific negative electrode active materials (such as lithium titanate or titanium oxide). This composite structure leverages the thermal stability of acrylic resin and the electrochemical properties of the active materials to achieve both good adhesion and high temperature reliability, resolving the contradiction between strength and reliability.
2Reliability
If acrylic resin is used as the binder instead of fluorine-based resin, then high temperature durability is improved, but adhesion strength may be reduced
Solution Approach 1:
The invention applies local quality by introducing specific functional groups (carboxyl, hydroxyl, or amine groups) at specific locations within the acrylic resin binder structure. These functional groups are strategically positioned to enhance interfacial bonding with the current collector through chemical interactions, while the bulk acrylic resin structure maintains its thermal stability. This localized functional enhancement allows the binder to achieve both high temperature durability and adequate adhesion strength.
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 battery achieves improved high temperature durability and cycle performance by preventing the swelling of the acrylic resin binder, maintaining electron conduction and reducing internal resistance.
Implementation Method 1
the acrylic resin binder, instead of the fluorine-based resin such as PVdF, hardly swells at a high temperature
Implementation Method 2
a titanium-containing metal oxide having lithium ions inserted into and extracted from
Implementation Method 3
network of an electron conduction of the negative electrode becomes disconnected
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
According to one embodiment, a nonaqueous electrolyte secondary battery includes a positive electrode, a negative electrode, and a nonaqueous electrolyte. The negative electrode includes a negative electrode current collector and a negative electrode mixed-material layer disposed on the negative electrode current collector. The negative electrode current collector includes a metallic foil. The negative electrode mixed-material layer includes a titanium-containing metal oxide having lithium ions inserted into and extracted from, and a binder that includes an acrylic resin. The negative electrode satisfies the following equation (I): α/β>1.36×10−2 In the equation, "α" represents a peel strength (N/m) between the current collector and the negative electrode mixed-material layer, and "β" represents a cutting strength (N/m) as measured according to a surface and interfacial cutting method in the negative electrode mixed-material layer.