Battery Separator Porosity Balance for Electrolyte Impregnability
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Solution Overview
Problem
Existing separator manufacturing methods fail to ensure adequate impregnability without additional processes or materials, limiting their application in large-volume batteries requiring high capacity and quick charging.
Innovation Solution
A separator design that adjusts the porosity of the substrate and inorganic layer to improve impregnability, with specific porosity and permeability relationships, using inorganic materials with a permittivity constant of 1 or more, piezoelectricity, or lithium ion transfer ability, and a BET of 3.0 m2/g or more, with the inorganic layer thickness being 30% or more of the total separator thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If porosity of separator substrate and inorganic layer is increased to improve impregnability, then lithium ion conductivity is improved, but mechanical strength and structural stability deteriorate
Solution Approach 1:
The invention applies parameter changes by precisely controlling the porosity values of both the separator substrate and inorganic layer to satisfy a specific mathematical relationship. This quantitative parameter optimization allows the structure to achieve high impregnability while maintaining mechanical integrity, resolving the contradiction between porosity and strength.
Solution Approach 2:
The invention uses a composite structure consisting of a separator substrate and an inorganic layer with complementary properties. The inorganic layer provides structural stability and heat resistance while the porous substrate enables ion transport, together achieving both high impregnability and mechanical strength through material composition optimization.
2Reliability
If porosity of separator substrate and inorganic layer is increased to improve impregnability, then lithium ion conductivity is improved, but structural stability deteriorates
Solution Approach 1:
The invention resolves this contradiction by establishing a specific parameter relationship between the porosity of the separator substrate and inorganic layer. This quantitative control ensures that even with high porosity values for improved impregnability, the structural stability is maintained through the balanced design of the composite structure.
Solution Approach 2:
The composite structure of separator substrate and inorganic layer provides synergistic effects where the inorganic layer contributes structural stability and thermal resistance while the porous substrate facilitates ion transport, achieving both high impregnability and structural stability simultaneously.
3Ease of manufacture
If conventional separator manufacturing methods are used without additional processes, then manufacturing complexity is reduced, but impregnability cannot be secured at predetermined level
Solution Approach 1:
The invention achieves high impregnability through parameter optimization rather than additional manufacturing processes. By controlling the porosity parameters of existing components to satisfy a specific relationship, the method maintains manufacturing simplicity while significantly improving impregnability performance.
Solution Approach 2:
The invention enables the separator components to self-optimize their performance through inherent porosity characteristics. The separator substrate and inorganic layer naturally achieve high impregnability when their porosity values satisfy the specified relationship, eliminating the need for additional impregnation processes or treatments.
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 separator achieves improved impregnability, allowing its use in large-volume batteries, and enables indirect checking of impregnability through permeability measurement, suitable for devices like electric vehicles and power storage devices.
Implementation Method 1
The coating layer including the inorganic material and the binder is configured to have a pore structure such that a space, into which a liquid electrolytic solution is introduced, is increased, whereby impregnability with the electrolytic solution and lithium ion conductivity are improved.
Implementation Method 2
The separator, which blocks electrical connection between the positive electrode and the negative electrode to secure insulation
Implementation Method 3
a porous material such that lithium ions can move
Data Source
AI summary
A separator including a separator substrate including a porous material and an inorganic layer on at least one surface of the separator substrate. Each of the separator substrate and the inorganic layer has porosity related to permeability of the separator: (10×porosity of separator substrate)−(4×porosity of inorganic layer)≤permeability of separator.