Multilayer Porous Membrane for Thin Battery Separator Friction Control
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Solution Overview
Problem
Nonaqueous electrolyte solution battery separators face challenges in reducing thickness while maintaining heat resistance, strength, and preventing friction, which are essential for increasing energy density and ensuring safety.
Innovation Solution
A multilayer porous membrane with a polyolefin resin-based microporous membrane and a porous layer containing inorganic particles, where the mean particle size of the inorganic particles is between 0.01 μm and 0.60 μm, the weight ratio of inorganic particles is greater than 80%, and the friction coefficients are optimized to reduce friction and enhance heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the separator thickness is reduced to increase energy density, then the energy density is improved, but the heat resistance and strength deteriorate
Solution Approach 1:
The patent applies composite materials by combining a polyolefin microporous membrane with a porous layer containing inorganic particles (such as alumina, silica, or boehmite) dispersed in a binder resin. This composite structure provides both the mechanical strength and heat resistance of inorganic materials while maintaining the flexibility and ion permeability of the polyolefin substrate, enabling thin separator design without sacrificing thermal safety
Solution Approach 2:
The patent utilizes porous materials by forming a porous layer with controlled porosity (30-80%) on the microporous membrane. The porous structure allows efficient ion transport while the inorganic particles provide thermal stability. The pore size and distribution are optimized to maintain ion permeability even at reduced separator thickness, resolving the contradiction between thinness and functional performance
2Quantity of substance
If the separator thickness is reduced to increase energy density, then the energy density is improved, but the strength deteriorates
Solution Approach 1:
The composite structure of polyolefin microporous membrane reinforced with inorganic particles provides enhanced mechanical strength. The inorganic particle network acts as a reinforcing skeleton that maintains structural integrity at reduced thickness, while the polyolefin matrix provides flexibility and toughness
Solution Approach 2:
The patent applies local quality by creating a porous layer with specific mechanical properties on the surface of the microporous membrane. The inorganic particles are strategically distributed to provide localized reinforcement where needed, such as at the surfaces that contact electrodes, while maintaining overall flexibility of the separator
3Ease of operation
If the friction coefficient is reduced to improve pin removal property, then the pin removal property is improved, but the adhesion between separator and electrodes may deteriorate
Solution Approach 1:
The patent optimizes the friction coefficient by adjusting the particle size distribution (D50: 0.01-0.60 μm), inorganic particle content (70-90 vol%), and binder resin composition of the porous layer. These parameter changes create a surface with controlled friction characteristics that facilitate pin removal while maintaining sufficient adhesion through the porous structure's interaction with the electrolyte and electrode surfaces
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 effectively reduces friction, improves heat resistance, and increases energy density in nonaqueous electrolyte solution batteries while maintaining the pin removal property and safety, even with reduced separator thickness.
Implementation Method 1
the friction coefficients are optimized to reduce friction and enhance heat resistance
Implementation Method 2
Separators are generally required to have ion permeability
Implementation Method 3
separators comprising microporous membranes with polyolefin resins have been used
Data Source
AI summary
The object of the disclosure is to provide a multilayer porous membrane that can improve heat resistance (ability to inhibit heat shrinkage) and strength when the thickness of a nonaqueous electrolyte solution battery separator has been decreased, while inhibiting friction on the separator surface as a whole, and that can also increase energy density in a nonaqueous electrolyte solution battery, as well as a nonaqueous electrolyte solution battery separator and a nonaqueous electrolyte solution battery comprising the same.