PVDF-Coated Battery Separator for Wide-Temperature Electrode Adhesion
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Solution Overview
Problem
Conventional separators for non-aqueous secondary batteries with adhesive porous layers containing polyvinylidene fluoride type resin have a narrow temperature range for effective adhesion between the electrode and separator, limiting battery performance and cycle life.
Innovation Solution
A separator with a porous substrate and an adhesive porous layer containing a polyvinylidene fluoride type resin, which includes vinylidene fluoride, a fluorine-containing monomer, and a specific monomer represented by Formula (1), with a molecular weight distribution ratio of 3.5 to 10 and a weight average molecular weight of 500,000 to 3,000,000, allowing for wide temperature range adhesion and improved cell strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional separator with adhesive porous layer containing polyvinylidene fluoride type resin is used, then adhesion between electrode and separator is improved, but the temperature range for effective adhesion is narrow
Solution Approach 1:
The invention changes the molecular weight distribution parameters of the polyvinylidene fluoride type resin, specifically setting the weight average molecular weight to number average molecular weight ratio (Mw/Mn) within 3.5 to 10 and weight average molecular weight within 500,000 to 3,000,000. This parameter optimization enables the adhesive porous layer to maintain effective adhesion across a wide temperature range of 60°C to 100°C, resolving the contradiction between adhesion strength and temperature range adaptability
Solution Approach 2:
The invention uses a composite structure consisting of a porous substrate combined with an adhesive porous layer containing polyvinylidene fluoride type resin with specifically controlled molecular weight distribution. This composite material design synergistically provides both strong adhesion capability and wide temperature range adaptability, overcoming the limitations of conventional single-material separators
2Strength
If heat press temperature is optimized for maximum adhesion, then adhesion strength is improved, but the manufacturing process becomes more restricted
Solution Approach 1:
By optimizing the molecular weight distribution parameters (Mw/Mn ratio of 3.5 to 10 and weight average molecular weight of 500,000 to 3,000,000), the invention expands the effective heat press temperature range to 60°C to 100°C. This allows manufacturers to select from multiple temperature conditions within this range, providing flexibility in manufacturing process design while maintaining strong adhesion, thus resolving the contradiction between adhesion strength and manufacturing flexibility
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 provides a non-aqueous secondary battery with enhanced adhesion, cycle characteristics, and load characteristics, maintaining battery performance across a wide temperature range and preventing electrode expansion and shrinkage-induced gaps.
Implementation Method 1
a separator having an adhesive porous layer containing a polyvinylidene fluoride type resin... When this separator is superimposed and thermally pressed on an electrode with an electrolyte solution included therein, the entire of the separator is well adhered to the electrode through the adhesive porous layer
Implementation Method 2
adhesion strength between the electrode and the separator changes depending on the temperature of heat press... improving the cycle life of a soft pack battery
Data Source
AI summary
An embodiment of the present invention provides a separator for a non-aqueous secondary battery, including: a porous substrate; and an adhesive porous layer provided on one side or both sides of the porous substrate and containing a polyvinylidene fluoride type resin, the polyvinylidene fluoride type resin including as monomer components vinylidene fluoride, a fluorine-containing monomer other than vinylidene fluoride and a monomer represented by Formula (1), a molecular weight distribution that is a ratio of a weight average molecular weight to a number average molecular weight being from 3.5 to 10, and a weight average molecular weight being from 500,000 to 3,000,000, in which R1 to R3: a hydrogen atom, a halogen atom, a carboxyl group or a derivative thereof, or a C1-5 alkyl group; X: a single bond, a C1-5 alkylene group, or a substituted C1-5 alkylene group; Y: a hydrogen atom, a C1-5 alkyl group, or an at least one hydroxy group-containing C1-5 alkyl group.