Aqueous Separator Slurry for Uniform Thin Battery Coatings
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing non-aqueous solvent-based coatings for lithium-ion battery separators are hazardous, costly, and environmentally unfriendly, and result in non-uniform, inflexible, and thick coatings that compromise battery performance and safety.
Innovation Solution
An aqueous slurry composition using anionic oxide nanoparticles and water-based polymeric binders is developed, ensuring uniform, flexible, and thin coatings by maintaining slurry stability and preventing aggregation, which can be directly applied to electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If non-aqueous solvent-based coatings are used, then PVDF can be dissolved and applied, but the solvents are hazardous, volatile, and environmentally unfriendly
Solution Approach 1:
The patent changes the fundamental parameter of the solvent system from non-aqueous (NMP, DMF, DMAC) to aqueous-based. This substitution eliminates the harmful properties of traditional solvents while maintaining the ability to dissolve or disperse PVDF through water-compatible dispersants and surfactants, thereby resolving the contradiction between manufacturability and environmental safety.
Solution Approach 2:
The patent employs disposable-like approach by using water as the primary solvent that can be easily evaporated or removed without requiring complex recovery systems. The aqueous system allows for simple drying processes compared to the costly and complex solvent recovery needed for hazardous organic solvents, making the process more economical and environmentally friendly.
2Ease of manufacture
If non-aqueous solvents are used for PVDF coating, then the coating can be formed, but the process is costly and has unfavorable environmental footprint
Solution Approach 1:
The patent fundamentally changes the solvent parameter from hazardous organic solvents to water-based systems. This enables simpler, lower-cost processing with reduced environmental footprint, as water requires no special disposal infrastructure and eliminates the need for expensive solvent recovery systems while maintaining effective PVDF coating formation.
Solution Approach 2:
The patent converts the typically problematic property of water (its inability to dissolve many polymers) into a benefit by using water as a safe, inexpensive, and environmentally friendly alternative to hazardous solvents. Through the use of appropriate dispersants and surfactants, the patent achieves effective PVDF coating with water, turning a limitation into an advantage for sustainability and cost reduction.
3Ease of manufacture
If cationic surface charged alumina is used, then the separator coating can be formed, but the coating is non-uniform and thick
Solution Approach 1:
The patent inverts the surface charge property of the alumina particles from cationic to anionic. This inversion fundamentally changes the interaction dynamics in the slurry, preventing particle aggregation and enabling uniform dispersion. The anionic charge creates electrostatic repulsion between particles, which maintains consistent spacing and prevents the formation of thick, non-uniform coatings, thereby achieving precise thickness control.
Solution Approach 2:
The patent changes the surface charge parameter of the alumina particles, which fundamentally alters the colloidal stability and dispersion characteristics of the slurry. This parameter change from cationic to anionic charge enables better control over particle distribution, resulting in uniform, thin coatings with precise thickness control comparable to commercial separators.
4Ease of manufacture
If micron-sized aluminum oxide is used, then the separator can be formed, but the separator is inflexible and thicker than commercially available separators
Solution Approach 1:
The patent inverts the particle size parameter by using nanoscale alumina particles instead of micron-sized particles. This inversion fundamentally changes the rheological properties of the slurry and the resulting coating morphology. The nanoscale particles create a more flexible, thinner coating structure that drapes better and achieves the flexibility and thickness requirements of commercial separators.
Solution Approach 2:
The patent changes the particle size parameter from micron-scale to nanoscale, which fundamentally alters the mechanical properties of the resulting separator coating. The nanoscale particles enable the formation of thin, flexible coatings that maintain structural integrity while achieving the desired flexibility and thickness comparable to commercial PE/PP separators.
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 aqueous slurry composition produces stable, porous, and dimensionally stable separators that enhance battery safety and performance, reducing environmental impact and fabrication costs while allowing simultaneous casting with electrodes.
Implementation Method 1
The use of anionic oxide nanoparticles, which have a negative surface charge, prevents aggregation of the particles in the aqueous slurry composition
Implementation Method 2
The coating layer is formed from particles and/or a mixture of particles and an aqueous or water-based polymeric binder
Data Source
AI summary
The invention relates to an aqueous slurry composition comprising an aqueous-based polymeric binder and anionic oxide nanoparticles that can be used, for example, in coating of electrodes and/or separators in electrochemical devices. This coating after drying, is highly porous, electronically isolating, and exhibits high dimensional stability at elevated temperatures.