Porous Insulating Layer Binder for Battery Electrode Thickness Control
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Solution Overview
Problem
The existing methods for forming porous insulating layers in non-aqueous electrolyte rechargeable batteries result in increased thickness of the active material layer, leading to residual stress and deformation, which complicates the manufacturing process and affects battery performance.
Innovation Solution
A composition comprising an organic solvent with specific Hansen solubility parameters, insulating inorganic particles, and a polymer binder is used to form a porous insulating layer on the active material layer, which suppresses the thickness increase and prevents peeling phenomena, thereby maintaining the balance of residual stress and improving battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If material slurry for porous insulating layer is coated on active material layer, then insulating layer is formed to prevent internal short circuit, but active material layer thickness increases causing residual stress and deformation
Solution Approach 1:
The patent changes the chemical composition parameters of the binder polymer to achieve the desired effect. Specifically, it uses a copolymer containing 70-90 wt% of a first monomer (styrene, alpha-methylstyrene, or p-methylstyrene) and 10-30 wt% of a second monomer (acrylic acid, methacrylic acid, or itaconic acid). This specific compositional parameter range creates a binder that provides strong adhesion without causing excessive swelling, thus preventing thickness increase while maintaining insulating function.
Solution Approach 2:
The patent employs a composite binder system combining two different monomers with complementary properties. The first monomer (aromatic vinyl compound) provides structural integrity and low swelling, while the second monomer (carboxylic acid vinyl compound) provides polar groups for strong adhesion to the active material. This composite polymer structure achieves both adhesion and dimensional stability simultaneously.
2Productivity
If compression pressure is increased to achieve high energy density, then electrode density improves, but residual stress increases causing greater thickness increase during coating
Solution Approach 1:
The patent applies beforehand cushioning by designing a binder polymer with specific properties that preemptively counteract the adverse effects of compression-induced residual stress. The copolymer composition (70-90% first monomer, 10-30% second monomer) is selected to provide optimal balance between adhesion and swelling resistance, cushioning against the thickness increase that would otherwise occur during the coating process on pre-compressed electrodes.
Solution Approach 2:
The patent changes the polymer composition parameters to adapt to high compression conditions. The high content of first monomer (70-90%) provides dimensional stability under compression, while the controlled amount of second monomer (10-30%) ensures sufficient adhesion. This parameter optimization allows the binder to maintain performance on electrodes that have been compressed to high densities.
3Productivity
If design electrode density is increased to compensate for thickness increase, then energy density is maintained, but compression must be reduced affecting battery performance
Solution Approach 1:
The patent converts the potential harm of binder swelling into a benefit by carefully selecting monomer ratios. The second monomer (10-30% content) provides controlled swelling that ensures adequate adhesion, while the dominant first monomer (70-90% content) limits excessive swelling. This converts what could be harmful expansion into a beneficial adhesion mechanism without compromising overall thickness control or requiring density compensation.
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 solution effectively reduces the thickness increase of the active material layer, enhances the stability of the battery, and improves its high-temperature cycle-life characteristics by preventing swelling and peeling, thus ensuring better performance and integration into the battery device.
Implementation Method 1
A composition comprising an organic solvent with specific Hansen solubility parameters, insulating inorganic particles, and a polymer binder is used to form a porous insulating layer on the active material layer
Implementation Method 2
which suppresses the thickness increase and prevents peeling phenomena, thereby maintaining the balance of residual stress
Data Source
AI summary
A composition to form a porous insulating layer on an active material layer on a main surface of a current collector current collector is provided. The active material layer includes an active material to electrochemically intercalate and deintercalate lithium ions and an active material layer binder, the composition to form the porous insulating layer includes a solvent including an organic solvent, an insulating inorganic particle, and a binder, and the binder is a polymer obtained by polymerization of monomers including about 30 wt % to about 60 wt % of an aromatic vinyl compound, about 20 wt % to about 69 wt % of (meth)acrylic acid ester, about 5 wt % to about 35 wt % of (meth)acrylic acid ester including a hydroxy group or an ether group, and about 1 wt % to about 10 wt % of a vinyl compound including an acidic functional group, based on a total weight of the binder.