Polyurethane Separator Resin for Low Internal Resistance
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Solution Overview
Problem
The existing aqueous polyurethane resin dispersion for secondary battery separators has limitations in achieving low internal resistance and good output characteristics.
Innovation Solution
An aqueous polyurethane resin dispersion is developed, containing a polyurethane resin obtained by reacting a polyol, a polyisocyanate compound, and a chain extender, with the polyol comprising a polycarbonate polyol and a polyolefin polyol, and a crosslink density of 0.02 mol/kg or more and 0.28 mol/kg or less, which enhances the electrical properties of the separator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an aqueous polyurethane resin dispersion using polyisocyanate and polyolefin-based polyol is used for separator, then electrolyte solution resistance and adhesiveness are improved, but internal resistance and output characteristics remain insufficient
Solution Approach 1:
The patent applies parameter changes by precisely controlling the crosslink density of polyurethane resin within 0.02-0.28 mol/kg and adjusting polyol composition ratios (polycarbonate polyol 10-95 parts relative to polyolefin polyol). These parameter optimizations resolve the contradiction by achieving both low internal resistance and good output characteristics simultaneously
Solution Approach 2:
The patent uses composite materials by combining polycarbonate polyol and polyolefin polyol in specific ratios to create a blended polyol system. This composite approach allows the separator to achieve both low internal resistance (from polycarbonate component) and adequate mechanical strength (from polyolefin component), resolving the power characteristic contradiction
2Power
If polycarbonate polyol content is increased to reduce internal resistance, then output characteristics improve, but separator strength may be compromised
Solution Approach 1:
The patent optimizes the polycarbonate polyol content parameter within 10-95 parts relative to 100 parts polyolefin polyol, with crosslink density controlled at 0.02-0.28 mol/kg. This parameter optimization ensures sufficient polycarbonate content for low internal resistance while maintaining polyolefin content for structural strength
Solution Approach 2:
The patent creates a composite polyol system where polycarbonate polyol provides low internal resistance and polycarbonate polyol provides mechanical strength. The synergistic combination in specific ratios resolves the contradiction between power characteristics and separator strength
3Strength
If crosslink density is increased to improve separator strength, then structural integrity improves, but internal resistance and output characteristics worsen
Solution Approach 1:
The patent precisely controls crosslink density within 0.02-0.28 mol/kg, avoiding excessive crosslinking. This parameter control prevents the formation of too many crosslink points that would increase internal resistance, while still providing sufficient structural strength through moderate crosslinking
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
This approach results in secondary batteries with low internal resistance and improved output characteristics, including better discharge average voltage and reduced internal resistance, by allowing the polycarbonate component to swell in the electrolyte solution while maintaining strength.
Implementation Method 1
by allowing the polycarbonate component to swell in the electrolyte solution while maintaining strength
Data Source
AI summary
A technology which exhibits a low internal resistance and good output characteristics is provided.An aqueous polyurethane resin dispersion for a secondary battery separator includes an aqueous polyurethane resin dispersion containing a polyurethane resin dispersed in water, the polyurethane resin being obtained by reacting a polyol, a polyisocyanate compound, and a chain extender. The polyol contains a polycarbonate polyol. The polyurethane resin has a crosslink density of 0.02 mol/kg or more and 0.28 mol/kg or less.