Battery Pack Potting Composition With Low-Exotherm Structural Curing
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Solution Overview
Problem
Existing potting materials for structural battery packs face challenges such as high exothermicity during curing, difficulty in disassembly and reuse of battery cells, limited mechanical strength, and health and safety hazards due to high monomeric isocyanate content, which complicates manufacturing and increases costs.
Innovation Solution
A two-component composition comprising a first component with polyol, catalysts for hydroxyl and isocyanate reactions, and a second component with oligomeric polyisocyanate, utilizing a trialkylphosphine catalyst for controlled trimerization, allows for a two-step curing process with limited exothermicity, high mechanical strength, and adjustable foaming ratio, ensuring safety and ease of cell disassembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional 2C-PU foam materials are used for filling interstitial volume in battery packs, then weight reduction and shock-absorbing properties are achieved, but the material lacks sufficient mechanical strength and structural stability
Solution Approach 1:
The patent uses a two-component polyurethane system combining polyol and polyisocyanate that forms a composite foam structure with both lightweight cellular morphology and high mechanical strength through controlled cross-linking reactions
Solution Approach 2:
The patent modifies the chemical composition parameters of the foam material by using specific polyol-polyisocyanate ratios and adding cross-linking agents to achieve enhanced mechanical properties while maintaining low density
2Strength
If highly cross-linked 2C-PU material is used to provide structural strength, then mechanical properties and stiffness are improved, but the exothermic reaction during curing increases and becomes difficult to control
Solution Approach 1:
The patent divides the curing process into multiple stages by using a two-component system that cures progressively, allowing heat dissipation between reaction stages and preventing runaway exothermic reactions
Solution Approach 2:
The patent introduces a catalyst system that mediates the reaction rate between polyol and polyisocyanate, controlling the exothermicity by adjusting catalyst type and concentration to achieve manageable curing temperatures
3Productivity
If monomeric isocyanates are used in high concentrations to achieve fast curing, then curing speed is improved, but health and safety hazards increase due to toxicity and reactivity
Solution Approach 1:
The patent changes the physical state parameter of isocyanates from monomeric to oligomeric/polymeric forms, which reduces volatility and toxicity while maintaining reactive functionality for curing
Solution Approach 2:
The patent uses oligomeric/polymeric polyisocyanates that are less hazardous than monomeric forms, accepting slightly longer handling time in exchange for significantly improved safety and reduced ventilation requirements
4Strength
If the foam material is made very stiff to provide structural support, then mechanical rigidity is improved, but the material becomes difficult to process and apply in battery pack assembly
Solution Approach 1:
The patent creates a time-dependent material system that transitions from liquid/paste state during application to rigid foam during curing, allowing easy processing initially followed by development of structural rigidity
Solution Approach 2:
The patent applies the foam material in a uncured or partially cured state where it remains fluid and easy to inject into battery pack cavities, then allows it to cure and stiffen in place to provide the required structural support
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 safe, efficient curing with minimal thermal impact, provides high mechanical strength, and allows for cell disassembly, while maintaining electrical resistivity and thermomechanical stability within the battery pack's operating temperature range.
Implementation Method 1
wherein said catalyst C2 is a trialkylphosphine compound
Implementation Method 2
at least one catalyst C2 for catalyzing the trimerization reaction of isocyanate groups
Implementation Method 3
at least one catalyst C1 for catalyzing the reaction between hydroxyl groups and isocyanate groups
Implementation Method 4
such as high exothermicity during curing
Data Source
AI summary
A two-component composition consisting of a first component and a second component; wherein the first component includes: at least one polyol having an average OH functionality of at least 2; at least one first catalyst for catalyzing the reaction between hydroxyl groups and isocyanate groups; at least one second catalyst for catalyzing the trimerization reaction of isocyanate groups; optionally water; and preferably at least one foam stabilizer; and the second component includes at least one oligomeric or polymeric polyisocyanate; preferably at least one blowing agent; wherein the second catalyst is a trialkylphosphine compound; and wherein the molar ratio of all NCO groups in the two-component composition to all OH groups in the two-component composition is higher than 1.1, preferably higher than 1.3. The two-component composition is highly suitable as potting material for the production of structural battery packs using cell-to-body design.