Polyolefin Separator With Particle Layer For Battery Safety
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Solution Overview
Problem
Existing power storage device separators for high output lithium ion secondary batteries face challenges in balancing safety and performance, with previous solutions either compromising on porosity or shutdown functionality.
Innovation Solution
A polyolefin based porous film laminated with a particle-containing layer containing cellulose based resin, inorganic particles, and thermoplastic resin particles with a melting point of 100 to 140°C, which provides high heat resistance, mechanical properties, and a controlled shutdown function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heat resistant porous polymer layer is added to the porous polyolefin film, then heat resistance is improved, but porosity decreases
Solution Approach 1:
The patent applies composite materials by combining a porous polyolefin film with a particle-containing layer that includes heat-resistant inorganic particles (such as alumina, silica, or titania) dispersed in a binder resin. This composite structure provides heat resistance through the inorganic particles while maintaining porosity through the porous film substrate, thereby resolving the contradiction between heat resistance and porosity.
Solution Approach 2:
The patent applies local quality by concentrating the heat-resistant inorganic particles specifically in the particle-containing layer that is applied to the surface of the porous polyolefin film. This localized approach ensures that heat resistance is enhanced where needed (at the separator surface) while the bulk porous structure maintains its high porosity for ion permeability.
2Reliability
If a protect layer composed of inorganic particles and heat resistant polymer is added, then safety is improved, but battery performance deteriorates
Solution Approach 1:
The patent applies porous materials by utilizing the inherent porosity of the polyolefin film substrate and ensuring the particle-containing layer does not fill these pores. The porous structure allows efficient ion permeability for high battery performance while the inorganic particles embedded in the layer provide safety through heat resistance and dimensional stability.
Solution Approach 2:
The patent applies composite materials by creating a particle-containing layer with inorganic particles dispersed in a binder resin that is applied to the porous polyolefin film. This composite structure enhances safety through the heat-resistant inorganic particles while maintaining the porous film's ion permeability, thereby achieving both safety and high battery performance.
3Reliability
If the shutdown temperature is adjusted for different active materials, then safety is improved, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by adjusting the composition of the particle-containing layer, specifically varying the types and ratios of inorganic particles and binder resin, to control the shutdown temperature. This allows the separator to be tailored for different active materials (such as lithium cobalt oxide, lithium manganese oxide, or lithium iron phosphate) without fundamentally changing the separator structure, thereby achieving safety optimization with minimal increase in device complexity.
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 achieves both high battery performance and safety characteristics, ensuring effective operation as a power storage device separator with improved heat resistance, mechanical properties, and a functional shutdown mechanism.
Implementation Method 1
thermoplastic resin particles with a melting point of 100 to 140°C
Implementation Method 2
inorganic particles, and thermoplastic resin particles with a melting point of 100 to 140°C, which provides high heat resistance
Implementation Method 3
polyolefin based porous film laminated with a particle-containing layer
Data Source
AI summary
Disclosed is a separator for electricity storage devices, which achieves a balance between excellent battery performance and safety at a high level by providing a polyolefin porous film with a particle layer. The separator for electricity storage devices is characterized in that a particle-containing layer containing a cellulose resin, inorganic particles and a thermoplastic resin particles having a melting point of 100-140 DEG C is formed on at least one side of a polyolefin porous film.