Battery Separator with Optimized Inorganic Filler Volume Fraction
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Solution Overview
Problem
Current separators for non-aqueous secondary batteries face challenges in achieving a balance between ion permeability, thermal dimensional stability, and adhesion to electrodes, leading to potential safety issues and deterioration in battery performance.
Innovation Solution
A separator configuration featuring a porous substrate with a heat-resistant porous layer composed of resin particles and inorganic fillers, where the volume proportion of the inorganic filler is optimized to provide excellent ion permeability and thermal stability, and an adhesive porous layer for improved adhesion to electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyolefin porous membrane is used as a separator, then the shutdown function is improved, but the heat resistance deteriorates because the separator may be melted in its entirety when exposed to high temperatures
Solution Approach 1:
The patent uses a composite structure consisting of a polyolefin porous membrane (providing shutdown function) combined with a heat-resistant porous layer containing inorganic filler particles (providing heat resistance). This composite material approach allows both the shutdown function and heat resistance to coexist without compromising either property.
2Temperature
If a porous layer containing resin and filler is added to improve heat resistance, then the heat resistance is improved, but the ion permeability deteriorates
Solution Approach 1:
The heat-resistant porous layer is designed with a porous structure that allows ion transport. The layer contains inorganic filler particles distributed within a resin matrix, creating a porous network that provides both heat resistance and ion permeability pathways, thus resolving the contradiction between these two properties.
3Strength
If a porous layer containing resin and filler is added to improve adhesion, then the adhesion to electrode is improved, but the ion permeability deteriorates
Solution Approach 1:
The porous structure of the heat-resistant porous layer provides both adhesion to the electrode and pathways for ion transport. The resin matrix ensures good adhesion to the electrode while the porous network maintained by inorganic filler particles allows ion permeability, thus resolving the contradiction between adhesion and ion permeability.
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 enhances the battery's safety and performance by maintaining ion permeability and thermal stability while ensuring strong adhesion to electrodes, resulting in improved battery characteristics and safety.
Implementation Method 1
a heat resistant porous layer that is provided on one side or both sides of the porous substrate, that is an aggregate of resin particles and an inorganic filler
Implementation Method 2
a porous substrate, and a heat resistant porous layer that is provided on one side or both sides of the porous substrate
Implementation Method 3
an adhesive porous layer for improved adhesion to electrodes
Data Source
AI summary
Provided is a separator for a non-aqueous secondary battery, including: a porous substrate, and a heat resistant porous layer that is provided on one side or both sides of the porous substrate, that is an aggregate of resin particles and an inorganic filler, and that satisfies the following expression (1). In expression (1), Vf is a volume proportion (% by volume) of the inorganic filler in the heat resistant porous layer, and CPVC is a critical pigment volume concentration (% by volume) of the inorganic filler. Also provided is a separator for a non-aqueous secondary battery, including: a porous substrate, a heat resistant porous layer that is provided on one side or both sides of the porous substrate, that includes a resin and an filler, and that satisfies the following expression (2), and an adhesive porous layer that is provided on both sides of a stacked body of the porous substrate and the heat resistant porous layer, and that includes an adhesive resin. In expression (2), Vf is a volume proportion (% by volume) of the filler in the heat resistant porous layer, and CPVC is a critical pigment volume concentration (% by volume) of the filler.0.65≤Vf/CPVC≤0.99 expression (1)0.40≤Vf/CPVC≤0.99 expression (2)