Polyester Battery Packaging Film for Deep Draw Without Cracks
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Solution Overview
Problem
Film-shaped power storage device packaging materials face challenges in achieving deep concave formation for increased energy density due to susceptibility to cracks or pinholes, and polyamide films, while improving moldability, are inferior in mechanical strength and insulation properties compared to polyester films.
Innovation Solution
A power storage device packaging material comprising a laminate with a polyester film as the base material layer, a barrier layer, and a heat-sealable resin layer, where the polyester film has specific work hardening exponents, intrinsic viscosity, and rigid amorphous fraction ranges to enhance moldability and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a film-shaped packaging material is molded to form a deep concave portion, then the energy density of the power storage device is increased, but the packaging material is susceptible to cracks or pinholes
Solution Approach 1:
The patent changes the physical and chemical parameters of the polyester film, specifically controlling the work hardening exponent (n-value) to be 1.6 or more and 3.0 or less, intrinsic viscosity to be 0.66 or more and 0.95 or less, and rigid amorphous fraction to be 28% or more and 60% or less. These parameter adjustments enable the film to achieve deep concave formation without cracks or pinholes, resolving the contradiction between energy density improvement and reliability maintenance.
2Ease of manufacture
If a polyamide film is used as the base material layer, then the moldability of the packaging material is improved, but the mechanical strength and insulation properties are inferior compared to polyester film
Solution Approach 1:
The patent changes the parameters of polyester film to achieve moldability comparable to polyamide film. By controlling the work hardening exponent to be 1.6 or more and 3.0 or less, the polyester film attains excellent moldability while maintaining the superior mechanical strength and insulation properties inherent to polyester material, thus resolving the contradiction without switching to polyamide.
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 power storage device packaging material with improved moldability and mechanical strength, reducing the risk of cracks and pinholes while maintaining excellent insulation properties.
Implementation Method 1
the polyester film has a work hardening exponent of 1.6 or more and 3.0 or less in both longitudinal and width directions
Implementation Method 2
the heat-sealable resin layer is heat-sealed to another heat-sealable resin layer
Data Source
AI summary
A power storage device packaging material includes a laminate including at least a base material layer, a barrier layer, and a heat-sealable resin layer in this order, wherein the base material layer contains a polyester film, and the polyester film has a work hardening exponent of 1.6 or more and 3.0 or less in both longitudinal and width directions, with a difference of 0.5 or less between the work hardening exponents in the longitudinal and width directions, an intrinsic viscosity of 0.66 or more and 0.95 or less, and a rigid amorphous fraction of 28% or more and 60% or less.