Battery Separator Pore Structure for Heat Resistance and Ion Flow
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Solution Overview
Problem
Existing separators for electrochemical devices, such as secondary batteries, face issues with increased thickness, decreased permeability, and reduced wettability due to the use of multilayer structures, leading to degraded battery performance and stability.
Innovation Solution
A separator with specific pore diameter ranges (D10: 180 nm ≤ D10 ≤ 350 nm, D50: 380 nm ≤ D50 ≤ 650 nm, D90: 670 nm ≤ D90 ≤ 1000 nm) and an inorganic particle layer on a porous substrate, enhancing heat resistance and adhesive strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a multilayer separator is formed by laminating porous polymers or adding a coating layer with binder and inorganic particles, then the adhesive strength and heat resistance are improved, but the thickness increases and permeability decreases
Solution Approach 1:
The patent uses a porous substrate as the base layer and forms an inorganic particle layer with controlled porosity. The porous structure allows ion transport while maintaining mechanical strength and heat resistance, avoiding the need for thick non-porous coating layers that would block ion flow.
Solution Approach 2:
The separator combines organic porous polymer substrate with inorganic particles (such as Al2O3, SiO2, TiO2) to create a composite structure. This composite approach provides both the flexibility and porosity of polymers and the thermal stability and adhesive strength of inorganic materials, achieving improved performance without excessive thickness.
2Strength
If a multilayer separator is formed by laminating porous polymers or adding a coating layer with binder and inorganic particles, then the adhesive strength and heat resistance are improved, but the wettability decreases
Solution Approach 1:
The porous structure of both the substrate and the inorganic particle layer provides capillary action that enhances electrolyte wettability. The controlled pore size distribution (D10: 180-350 nm, D50: 380-650 nm, D90: 670-1000 nm) ensures adequate electrolyte penetration while maintaining mechanical integrity.
Solution Approach 2:
The inorganic particles are distributed throughout the coating layer to create local regions of enhanced surface energy and wettability. This local modification of surface properties improves overall electrolyte contact without requiring a complete change in the base polymer material.
3Productivity
If the separator thickness is reduced to improve permeability, then the ion migration is enhanced, but the mechanical stability and chemical stability decrease
Solution Approach 1:
The composite structure of porous polymer matrix reinforced with inorganic particles provides enhanced mechanical strength at reduced thickness. The inorganic particles act as structural support elements that prevent membrane collapse and maintain pore structure integrity, enabling thin separators with high permeability and adequate mechanical stability.
Solution Approach 2:
The optimized porous structure with specific pore diameter ranges maintains high ion permeability while the interconnected pore network provides structural reinforcement. The porosity is engineered to balance ion transport efficiency with mechanical strength, avoiding the need for excessive thickness.
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 ensures uniform lithium ion migration, suppresses side reactions, and maintains battery performance by maintaining optimal moisture content and adhesive strength, thereby improving thermal stability and charge/discharge characteristics.
Implementation Method 1
The pore diameters of the inorganic particle layer satisfies the following Equations 1 to 3: 180 nm ≤ D10 ≤ 350 nm, 380 nm ≤ D50 ≤ 650 nm, 670 nm ≤ D90 ≤ 1000 nm, wherein the inorganic particles have an average particle diameter (D50) of 0.1 μm to 10.0 μm
Implementation Method 2
a separator having excellent heat resistance and adhesive strength... ensures uniform lithium ion migration, suppresses side reactions, and maintains battery performance by maintaining optimal moisture content
Data Source
AI summary
Embodiments of the present disclosure relate to a separator having pore diameters D10, D50, and D90 satisfies all of 180 nm≤D10≤350 nm, 380 nm≤D50≤650 nm, and 670 nm≤D90≤1000 nm. The separator according to an embodiment has improved heat resistance by satisfying the predetermined pore diameter ranges, and a battery comprising the separator may have improved performance.