Self-Assembled CPP Base Film for Pouch Battery Gas Discharge
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Solution Overview
Problem
Existing aluminum-plastic films for lithium-ion battery pouches fail to effectively discharge high-temperature gas, leading to potential battery explosions due to high heat sealing strength, which is critical for safety in high-temperature scenarios.
Innovation Solution
A self-assembled CPP base film with a heat sealing layer, support layer, and composite layer, utilizing organic micro-nano thermal conductive materials to induce phase transformation and micropore formation, allowing gas discharge under high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the heat sealing strength of the CPP base film is increased to ensure long-term safety, then the sealing reliability is improved, but the ability to discharge high-temperature gas deteriorates
Solution Approach 1:
The patent modifies the molecular structure parameters of polypropylene by introducing comonomers (ethylene, propylene) to create random copolymers with controlled composition ratios. This changes the crystallinity and melting characteristics of the material, enabling it to maintain high sealing strength at normal temperatures while becoming sufficiently soft and porous at elevated temperatures to allow gas discharge.
Solution Approach 2:
The invention uses composite material structure by combining different types of polypropylene (homopolymer, random copolymer) in specific proportions. The composite formulation creates a multi-phase structure where different components contribute different properties: one phase provides sealing strength while another phase enables thermal softening and gas permeability at high temperatures.
2Strength
If the heat sealing strength is maintained high for safety, then the sealing performance is improved, but the ductility and flexibility of the film deteriorates
Solution Approach 1:
The patent adjusts compositional parameters of polypropylene by controlling the ratio of homopolymer to random copolymer components. This parameter optimization allows the material to exhibit both high strength and good ductility: the homopolymer provides structural strength while the random copolymer segments provide chain flexibility and elongation capability.
Solution Approach 2:
The invention creates a composite polypropylene system combining rigid crystalline phases (from homopolymer) and amorphous flexible phases (from random copolymer). This composite structure enables the film to simultaneously achieve high heat sealing strength and good ductility for forming and sealing operations.
3Ease of manufacture
If the CPP base film uses single-layer structure, then the manufacturing simplicity is maintained, but the functional performance for both sealing and gas discharge deteriorates
Solution Approach 1:
The patent divides the CPP base film into multiple functional layers with distinct compositions: a first layer rich in random copolymer for gas discharge functionality, and a second layer with balanced composition for sealing strength. This segmentation allows each layer to specialize in one function while the composite structure achieves both functions simultaneously.
Solution Approach 2:
The invention applies local quality differentiation by giving different compositional characteristics to different regions/layers of the film. The first layer has higher random copolymer content for gas permeability, while the second layer has optimized composition for sealing. This local optimization enables the whole film to achieve superior dual functionality.
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 film ensures safe gas discharge under high temperatures, preventing battery bulging and explosion by adjusting heat sealing strength, while maintaining good bonding and electrolyte resistance.
Implementation Method 1
utilizes organic micro-nano thermal conductive materials to induce the CPP heat sealing layer to produce a self-assembly function
Implementation Method 2
induce phase transformation and micropore formation, allowing gas discharge under high temperatures
Data Source
AI summary
Disclosed is a self-assembled cast polypropylene (CPP) base film of an aluminum-plastic film for new energy pouch batteries and a preparation method thereof. The base film comprises a self-assembled heat sealing layer, a support layer and a composite layer. The preparation process includes charging the raw materials of three layers into a three-layer co-extrusion casting machine and setting the relevant parameters for preparation, then performing a corona treatment. The present disclosure utilizes an organic hybrid micro-nano thermal conductive material to induce the heat sealing layer to produce a self-assembly function in a high temperature environment after heat sealing, thereby effectively preventing the pouch batteries from short circuit or explosion in a high temperature environment.