Titania-Coated Battery Separator for Heat and Compression Stability
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Solution Overview
Problem
Lithium-ion battery separators face challenges in maintaining mechanical performance under compressive stress and high temperature conditions, with existing materials like polyolefin showing insufficient melt integrity, leading to decreased ionic conductivity and safety concerns.
Innovation Solution
A high thermal-stability separator is developed with a porous substrate and an inorganic layer comprising inorganic particles and a binder, coated with a titanium oxide or titanium hydroxide film, which is deposited using chemical solution deposition to enhance compression retention and high-temperature melt integrity while maintaining air permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polyolefin materials are used for separator, then ease of manufacture is improved, but high temperature melt integrity deteriorates
Solution Approach 1:
The patent applies composite materials by combining polyolefin base material with titanium oxide and titanium hydroxide coatings. This creates a multi-component structure where the polyolefin provides ease of manufacture and basic separator functions, while the titanium oxide/hydroxide layers provide high-temperature stability and prevent melt integrity degradation. The composite structure resolves the contradiction by integrating materials with complementary properties.
Solution Approach 2:
The patent changes the thermal parameters of the separator by introducing titanium oxide and titanium hydroxide coatings that raise the thermal rupture temperature from the original polyolefin melting point to above 170°C. This parameter change maintains ease of manufacture with polyolefin while fundamentally improving high-temperature reliability through the coating layers.
2Strength
If separator compression resistance is strengthened, then mechanical performance is improved, but air permeability deteriorates
Solution Approach 1:
The patent applies local quality by creating a porous coating structure that provides compression resistance only where needed (in the coating layers on electrode-facing surfaces) while maintaining open pore channels for ion transport. The titanium oxide/hydroxide coating is applied locally to the separator surfaces, providing mechanical reinforcement without blocking the bulk porous structure's air permeability.
Solution Approach 2:
The patent uses porous materials for the titanium oxide and titanium hydroxide coatings, creating a hierarchical porous structure. The coating layers have controlled porosity that allows ion and air passage while the porous framework provides compression resistance. This resolves the contradiction by making the coating itself porous rather than dense, maintaining air permeability while gaining mechanical strength.
3Reliability
If inorganic layer is added to porous substrate, then high temperature melt integrity is improved, but device complexity increases
Solution Approach 1:
The patent extracts the high-temperature stability function from the bulk separator material and places it in a separate coating layer. Instead of making the entire separator complex, only the surface layers contain titanium oxide/hydroxide, while the bulk remains simple polyolefin. This extraction approach improves high-temperature reliability without substantially increasing overall device complexity.
Solution Approach 2:
The patent uses thin film coatings of titanium oxide and titanium hydroxide on the separator surfaces. These thin films provide the necessary high-temperature integrity function with minimal added complexity. The coatings are applied as thin layers rather than thick structures, maintaining simplicity while achieving the reliability improvement.
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 over 90% compression retention and less than 35% decrease in air permeability, with a thermal rupture temperature above 170°C, ensuring safety and maintaining ionic conductivity, thus addressing the mechanical and thermal stability issues of lithium-ion batteries.
Implementation Method 1
the titanium oxide film and/or the titanium hydroxide film is/are deposited by chemical solution deposition by sequentially applying a precursor solution and a reactive solution on the porous film to make the reactive solution react with the precursor solution
Data Source
AI summary
A high thermal-stability separator and method for manufacturing thereof are disclosed. The high thermal-stability separator comprises a porous film and a titanium oxide or/and titanium hydroxide film, wherein the porous film comprises a porous substrate and a inorganic layer, wherein the inorganic layer comprises a plurality of inorganic particles and a binder, the inorganic layer is formed on at least one surface of the porous substrate, and the porous substrate and the inorganic layer have a plurality of interconnected porous structures; and the titanium oxide or/and titanium hydroxide film is formed on the surface and the inner walls of porous structures of the porous film. The present high thermal-stability separator can provide enhanced compression retention and excellent high temperature melt integrity, and maintain a satisfied air permeability (Gurley) after compression.