Aqueous PVDF Ceramic Coated Separators for Lithium Batteries
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Solution Overview
Problem
Existing non-aqueous solvent-based ceramic coatings for lithium batteries are environmentally unfriendly, costly, and pose safety concerns due to volatility and flammability, necessitating the development of aqueous-based alternatives that offer improved performance, safety, and cost-effectiveness.
Innovation Solution
Aqueous-based ceramic coated separators for lithium batteries using a polymeric binder, such as PVDF, combined with ceramic particles and water-soluble polymers like polyvinyl alcohol, applied via a stable slurry mixture that ensures high adhesion and thermal stability, preventing oxidation reactions and enhancing safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-aqueous solvent-based ceramic coatings are used, then coating stability and adhesion are improved, but environmental friendliness deteriorates and safety concerns arise due to volatility and flammability
Solution Approach 1:
The patent changes the fundamental parameter of the coating medium from non-aqueous solvents (acetone, NMP, DMF) to aqueous-based solutions. This substitution eliminates the harmful volatility and flammability characteristics while maintaining coating effectiveness through careful formulation of the aqueous slurry with ceramic particles and polymeric binders
Solution Approach 2:
The patent converts the traditionally harmful non-aqueous solvents into beneficial aqueous components by demonstrating that water-based formulations can achieve comparable or superior coating adhesion and stability when properly formulated with appropriate binders and ceramic particle distributions, thereby eliminating environmental and safety hazards
2Object-affected harmful factors
If aqueous-based ceramic coatings are used, then environmental friendliness and safety are improved, but coating stability and adhesion may deteriorate
Solution Approach 1:
The patent employs composite material formulation by combining ceramic particles (alumina, silica, titania) with polymeric binders (PVDF, carboxymethyl cellulose, polyvinyl alcohol) in an aqueous medium. This composite approach ensures that the aqueous-based coating achieves sufficient adhesion and mechanical stability while maintaining the thermal and chemical benefits of ceramic materials
Solution Approach 2:
The patent introduces polymeric binders as intermediary substances that mediate between the aqueous medium and the ceramic particles, providing the necessary adhesion to the separator substrate. These binders act as intermediaries that bridge the gap between water-based formulation and ceramic particle attachment, ensuring coating stability without requiring harmful organic solvents
3Temperature
If ceramic particles are added to porous separator, then thermal stability is improved, but porosity may deteriorate
Solution Approach 1:
The patent applies local quality by coating ceramic particles selectively on the separator surface rather than throughout the bulk structure. This surface coating approach maintains the internal porosity and ion transport pathways of the separator while providing enhanced thermal stability at the critical electrode-separator interface where thermal runaway would initiate
Solution Approach 2:
The patent utilizes porous ceramic materials (alumina, silica, titania) that inherently possess porous structures. These porous ceramic coatings maintain ion permeability while providing thermal stability, as the ceramic pores allow electrolyte penetration and ion transport while the ceramic framework prevents thermal runaway and maintains structural integrity at elevated temperatures
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-based ceramic coated separators provide improved thermal integrity, safety, and performance by maintaining physical separation between electrodes, reducing shrinkage, and preventing oxidation reactions, thus enhancing the overall performance and longevity of lithium ion batteries.
Implementation Method 1
At temperatures above the melt temperature of the polymer matrix, the ceramic particles may retain their physical integrity and serve to maintain the physical separation barrier between the electrodes
Implementation Method 2
the polymeric matrix or binder may serve to provide adhesion between the ceramic particles, adhesion of the coating to the porous base membrane, and/or adhesion of the ceramic coated separator to the electrode
Implementation Method 3
a coating layer formed on at least one surface of the porous substrate, wherein the coating layer is formed from a coating slurry comprising ceramic particles and a polymeric binder
Data Source
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Figure 5~6(a)
AI summary
In accordance with at least selected embodiments, new or improved ceramic coated separators, membranes, films, or the like for use in lithium batteries, new or improved batteries including such ceramic coated separators, membranes, films, or the like, and methods of making or using such ceramic coated separators, membranes, films or the like are disclosed. In accordance with at least certain embodiments, new or improved aqueous or water-based polymeric coated separators, membranes, films, or the like are disclosed. In accordance with at least particular embodiments, new or improved aqueous or water-based polyvinylidene fluoride (PVDF) or polyvinylidene difluoride (PVDF) homopolymer or co-polymers of PVDF with hexafluoropropylene (HFP or [-CF(CF3)-CF2-]), chlorotrifluoroethylene (CTFE), vinylidene fluoride (VF2-HFP), tetrafluoroethylene (TFE), and/or the like, blends and/or mixtures thereof, coated separators, membranes, films or the like, new or improved porous separators for use in lithium batteries, new or improved coating or application methods for applying a coating or ceramic coating to a separator for use in a lithium battery, new or improved PVDF or PVDF:HFP films or membranes, and/or the like are disclosed.