Polyolefin Separator Laminate for Battery Safety
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries face challenges in maintaining safety and performance capabilities, particularly in preventing internal short circuits due to breakage, and existing evaluation methods fail to ensure high safety while maintaining these characteristics.
Innovation Solution
A laminate comprising a porous film with polyolefin as the main component and a porous layer with fine particles, where the displacement during a nail penetration test from dielectric breakdown to electrical conduction is measured, ensuring a high level of safety and maintaining rate and resistance characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inorganic compounds or particles are dispersed in or laminated to the separator to prevent internal short circuits, then safety is improved, but manufacturing complexity and device complexity increase
Solution Approach 1:
The patent employs a porous coating layer containing insulating inorganic particles dispersed in a porous polymer matrix. This porous structure provides multiple benefits: it maintains ion permeability for battery operation, provides physical separation to prevent short circuits, and the insulating particles act as spacers to maintain electrode separation even under compression. The porous nature allows the coating to be thin while still providing effective safety functionality.
Solution Approach 2:
The separator is constructed as a composite material combining organic polymer components (base separator and coating matrix) with inorganic insulating particles. This composite structure leverages the mechanical flexibility and ion permeability of polymers while incorporating the high dielectric strength and thermal stability of inorganic materials, achieving enhanced safety without sacrificing battery performance.
2Reliability
If the separator structure is modified to enhance safety features, then reliability improves, but manufacturing precision requirements increase
Solution Approach 1:
The safety coating layer is applied to the separator base film before the separator is assembled into the battery. This preliminary application allows for controlled coating processes and quality assurance before the separator is installed, ensuring uniform thickness and proper adhesion. The coating is formed as a complete layer with insulating particles distributed throughout, providing consistent safety performance across the entire separator surface.
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 laminate effectively prevents internal short circuits while maintaining the battery's performance capabilities, ensuring a high level of safety and efficient ion permeability.
Implementation Method 1
a displacement in a thickness direction of the laminate during a period from when a dielectric breakdown occurs in the laminate to when the laminate is brought into electrical conduction
Implementation Method 2
maintaining various performance capabilities such as a rate characteristic and a resistance characteristic
Data Source
AI summary
Provided is a laminate which is capable of ensuring a high level of safety by preventing an internal short circuit due to, for example, breakage of a non-aqueous electrolyte secondary battery while maintaining various performance capabilities of the non-aqueous electrolyte secondary battery. A laminate (10) includes: a porous film containing polyolefin as a main component; and a porous layer containing fine particles; the porous layer being laminated to at least one side of the porous film, in an electrical conduction test by nail penetration in which test a displacement in a thickness direction of the laminate (10) during a period from when a dielectric breakdown occurs in the laminate (10) to when the laminate (10) is brought into electrical conduction is measured by use of a nail (2) of N50 specified in JIS A 5508 and under a condition in which the nail (2) descends at a descending speed of 50 μm/min, the displacement being not less than 20 μm and not more than 200 μm.