Coated Microporous Battery Separator for Low-Temperature Shutdown
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing battery separators face challenges in preventing thermal runaway and short circuits, particularly in lithium-ion batteries, while maintaining mechanical properties and efficiency, as conventional coatings may not effectively shut down ionic flow at lower temperatures and can be prone to shorts from lithium dendrite growth.
Innovation Solution
A coated microporous membrane with a coating comprising an inorganic component and adhesion polymers, such as fluoropolymers, that reduces surface friction and lowers shutdown onset temperature, enhancing safety and performance by improving adhesion and electrolyte absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a conventional coating is applied to the battery separator, then the mechanical properties are maintained, but the shutdown onset temperature is not sufficiently lowered and thermal runaway prevention is ineffective
Solution Approach 1:
The patent applies composite materials by combining inorganic particles (such as metal oxides or ceramic materials) with polymer matrix materials to form a coating layer on the battery separator. This composite structure enables the coating to achieve both mechanical strength and thermal response functionality, allowing the separator to shut down at lower temperatures while maintaining structural integrity during normal operation.
Solution Approach 2:
The patent utilizes parameter changes by designing the coating layer to undergo physical or chemical changes at specific temperature thresholds. The inorganic components are selected to facilitate shutdown at predetermined lower temperatures (e.g., 100-150°C), enabling the separator to change its permeability parameter in response to temperature increases, thus preventing thermal runaway before it reaches critical levels.
2Weight of moving object
If the separator thickness is reduced to meet lighter battery demands, then the battery weight decreases, but the separator becomes more prone to shorts from lithium dendrite growth
Solution Approach 1:
The patent employs porous materials by creating a coating layer with controlled porosity and pore structure on the thin separator. This porous coating allows for selective ion transport while physically blocking lithium dendrite growth. The pore size and distribution are optimized to permit normal lithium ion passage during charging/discharging while preventing dendrite penetration, thus enabling thin separator design without compromising safety.
Solution Approach 2:
The coating layer acts as an intermediary between the thin separator and the lithium dendrites. This intermediate layer provides a protective barrier that mediates the interaction between the separator and dendrite growth, preventing direct contact and shorts while maintaining ionic conductivity for normal battery operation.
3Reliability
If a coating is applied to improve thermal safety, then the shutdown temperature is lowered, but the surface friction increases affecting battery performance
Solution Approach 1:
The patent applies local quality by creating a coating layer with spatially varying properties - the coating has different compositions, porosities, or surface characteristics at different locations or depths. This allows the coating to provide thermal safety functions (shutdown capability) in specific regions while maintaining low surface friction in contact areas, thus resolving the contradiction between safety and performance.
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 coated microporous membrane achieves lower shutdown onset temperatures and reduced surface friction, providing enhanced safety and efficiency in lithium-ion batteries by preventing thermal runaway and soft shorts, while maintaining mechanical integrity.
Implementation Method 1
When the coating is wet with electrolyte, in some embodiments, the wet adhesion polymer swells or grows so that the average particle size of the wet adhesion polymer is larger than that of the inorganic component
Implementation Method 2
the coating comprises an inorganic component and at least one of a dry adhesion polymer and a wet adhesion polymer, and the coating has a thickness less than 5 microns, less than 3 microns, or one micron or less
Implementation Method 3
The coating may comprise, consist of, or consist essentially of an inorganic component and at least one of the following: a wet adhesion polymer and a dry adhesion polymer
Implementation Method 4
a coated microporous membrane with a coating comprising an inorganic component and adhesion polymers, such as fluoropolymers, that reduces surface friction and lowers shutdown onset temperature, enhancing safety and performance by improving adhesion and electrolyte absorption
Data Source
AI summary
Disclosed herein are battery separators that include a microporous membrane and a coating. The coating may comprise, consist, or consist essentially of polymeric components, inorganic components, or combinations thereof. The battery separators described herein are, among other things, thinner, stronger, and more wettable with electrolyte than some prior battery separators. The battery separators may be used in secondary or rechargeable batteries, including lithium ion batteries. The batteries may be used in vehicles or devices such as cell phones, tablets, laptops, and e-vehicles.