Separator Coating Powder Composition for Adhesion and Ion Conductivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing separator coatings for lithium-ion batteries face challenges in achieving a balance between dry adhesion, wet adhesion, ion conductivity, and heat stability, with polyvinylidene fluoride derivatives not fully addressing these needs.
Innovation Solution
A composition comprising polymers P1 and P2, where P1 is derived from vinylidene fluoride and P2 from a specific monomer, with a melting point and crystallization temperature difference greater than 40°C, providing a good compromise between adhesion, conductivity, and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyvinylidene fluoride (PVDF) and derivatives are used as separator coatings, then electrochemical stability and ion conductivity are improved, but adhesion properties and heat stability are insufficient
Solution Approach 1:
The patent uses a composite coating system comprising multiple layers: a polyolefin base layer, a PVDF intermediate layer, and a top coating layer containing PVDF combined with hydrophilic polymers (such as polyacrylonitrile, polyacrylic acid, or carboxymethyl cellulose) and inorganic particles (such as alumina, silica, or boehmite). This multi-layer composite structure allows each layer to contribute specific properties - the PVDF provides electrochemical stability and ion conductivity, while the hydrophilic polymers and inorganic particles enhance adhesion and heat stability, thus resolving the contradiction between ion conductivity and adhesion/heat stability
2Quantity of substance
If separator thickness is reduced, then energy density is improved, but mechanical strength and thermal resistance deteriorate
Solution Approach 1:
The patent employs porous inorganic particles (such as alumina, silica, boehmite, or titania) with specific pore structures and sizes (0.1-10 μm) within the separator coating. These porous materials provide mechanical reinforcement and thermal stability while maintaining high ion conductivity through the pore network. The porous structure allows the separator to achieve sufficient mechanical strength and thermal resistance at reduced thickness, thereby enabling higher energy density without compromising safety
3Temperature
If a multi-layer separator structure is implemented, then thermal resistance and mechanical strength are improved, but manufacturing complexity increases
Solution Approach 1:
The patent combines multiple functional components into a single integrated coating layer applied directly onto the polyolefin base separator. The coating layer simultaneously contains PVDF for electrochemical stability, hydrophilic polymers for adhesion enhancement, inorganic particles for thermal and mechanical reinforcement, and porogenic agents for pore formation. This integrated approach eliminates the need for separate multi-layer structures, simplifying the manufacturing process while maintaining thermal resistance and mechanical 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 composition achieves enhanced adhesion, conductivity, and thermal stability, making it suitable for use in lithium-ion battery separators.
Implementation Method 1
the difference between the melting point and the crystallization temperature of said composition is greater than or equal to 40° C.
Implementation Method 2
high dielectric constant, which promotes ion dissociation and thus conductivity
Data Source
AI summary
The present invention relates to a composition comprising a polymer P1 comprising monomer units derived from vinylidene fluoride and a polymer P2 comprising monomer units derived from a monomer M2 of formula R1R2C═C(R3)C(O)R in which the substituents R1, R2 and R3 are, independently of each other, selected from the group consisting of H and C1-C5 alkyl; R is selected from the group consisting of —NHC(CH3)2CH2C(O)CH3 or —OR′ with R′ selected from the group consisting of C1-C18 alkyl optionally substituted by one or more —OH group(s) or a five- or six-membered heterocycle comprising at least one nitrogen atom in its cyclic chain, characterised in that the difference between the melting temperature and the crystallisation temperature of the composition is greater than or equal to 40° C. and in that the composition is in powder form.