Separator Coating Layer Adhesion and Thermal Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing battery separators face challenges in achieving high adhesion and thermal stability while minimizing solvent residue and preventing short circuits due to thermal shrinkage and overheating, especially when using high boiling point solvents for dissolving high molecular weight polyvinylidene fluoride homopolymers.
Innovation Solution
A separator with a coating layer containing a polyvinylidene fluoride homopolymer of weight average molecular weight 1,000,000 g/mol or more, a polyvinylidene fluoride-hexafluoropropylene copolymer, and inorganic particles, where the solvent is present in an amount of 100 ppm or less, providing strong adhesion and heat dissipation through a suitable solvent like dimethylformamide and using dip coating for application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high molecular weight polyvinylidene fluoride homopolymer is used to improve adhesion, then adhesion strength increases, but solvent residue increases due to high boiling point
Solution Approach 1:
The patent changes the molecular weight parameter of the polyvinylidene fluoride homopolymer to 1,000,000 g/mol or more, which improves adhesion strength while the specific parameter control of solvent residue to 100 ppm or less addresses the harmful effect
Solution Approach 2:
The patent converts the high boiling point characteristic of the solvent, which causes residue, into a benefit by enabling complete dissolution of the high molecular weight polymer, and then uses controlled removal to achieve both strong adhesion and minimal residue
2Stability of the object's composition
If coating layer is applied to improve thermal stability, then thermal shrinkage resistance improves, but manufacturing complexity increases
Solution Approach 1:
The coating layer is applied in advance to the separator before battery assembly, providing thermal stability and shrinkage resistance beforehand, which simplifies the overall manufacturing process by preventing thermal issues before they occur
Solution Approach 2:
The patent uses a composite coating layer containing polyvinylidene fluoride homopolymer, polyvinylidene fluoride-hexafluoropropylene copolymer, and inorganic particles, which provides enhanced thermal stability while maintaining a relatively simple single-layer structure
3Stability of the object's composition
If solvent amount is increased to dissolve polymer, then polymer dissolution improves, but solvent residue increases
Solution Approach 1:
The patent controls the solvent amount parameter precisely to achieve complete polymer dissolution while limiting the final solvent residue to 100 ppm or less through the specified processing conditions
Solution Approach 2:
The patent uses a high boiling point solvent as an intermediary that can dissolve the high molecular weight polymer effectively, then removes it through controlled evaporation to leave minimal residue, serving as a temporary medium that facilitates dissolution without remaining in the final product
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 achieves excellent adhesion and thermal stability, suppressing thermal shrinkage and preventing short circuits, thereby enhancing battery performance and lifespan with a lightweight, slim structure.
Implementation Method 1
A separator, including a coating layer, the coating layer containing a polyvinylidene fluoride homopolymer, a polyvinylidene fluoride-hexafluoropropylene copolymer
Implementation Method 2
providing strong adhesion and heat dissipation through a suitable solvent like dimethylformamide
Implementation Method 3
using dip coating for application
Implementation Method 4
the solvent being present in an amount of about 100 ppm or less in the coating layer
Data Source
AI summary
A separator includes a coating layer, the coating layer containing a polyvinylidene fluoride homopolymer, a polyvinylidene fluoride-hexafluoropropylene copolymer, a solvent, and inorganic particles, the solvent being present in an amount of about 100 ppm or less in the coating layer.