Gas-Generating Separator Coating for Battery Flame Retardancy
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Solution Overview
Problem
Existing separators in lithium secondary batteries face challenges in achieving high temperature safety without generating additional reactants, being environmentally friendly, safe for living bodies, and maintaining battery capacity, while conventional flame retardants have limitations in effectiveness and safety.
Innovation Solution
A separator with a porous coating layer containing a gas generating agent, such as organic or inorganic foaming agents, is used to generate gas at specific temperatures, enhancing flame retardancy and safety without reducing battery capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bromine-based flame retardant is used in the separator, then flame retardancy is improved, but toxic substances are generated
Solution Approach 1:
The patent converts the harmful effect of bromine-based flame retardants (toxicity) into a beneficial alternative by using inorganic hydroxide-based flame retardants that generate non-toxic substances during decomposition. The inorganic hydroxide releases water vapor and forms protective char layers, achieving flame retardancy without generating harmful toxins, thus transforming the harmful chemical pathway into a safe one.
Solution Approach 2:
The patent changes the chemical composition parameter of the flame retardant from organic bromine-based compounds to inorganic hydroxide-based compounds. This parameter change fundamentally alters the decomposition products from toxic halogenated hydrocarbons to non-toxic water vapor and metal oxides, while maintaining or improving flame retardant performance through different mechanisms such as heat absorption and char formation.
2Object-generated harmful factors
If an inorganic hydroxide-based flame retardant is used, then non-toxicity and heat absorption are improved, but additional reactions with lithium may occur due to water produced by pyrolysis
Solution Approach 1:
The patent applies local quality by creating a coating layer with specific composition and structure on the separator surface. The inorganic hydroxide flame retardant is incorporated into a coating matrix that controls its decomposition behavior and limits water diffusion to lithium. The coating layer's localized structure ensures that even though water is produced by pyrolysis, it is contained and managed within the coating matrix, preventing harmful reactions with lithium while maintaining non-toxicity benefits.
Solution Approach 2:
The patent introduces a coating layer as an intermediary between the inorganic hydroxide flame retardant and the battery components. This coating layer acts as a mediator that controls the decomposition products' interaction with the environment, allowing safe release of non-toxic gases while preventing harmful water-lithium reactions through the coating's barrier and structural properties.
3Object-generated harmful factors
If a metal oxide is used as flame retardant, then non-toxicity is improved, but dispersion force is weak even with cyano-based resin
Solution Approach 1:
The patent uses composite materials by combining inorganic hydroxide flame retardant particles with a binder resin and dispersant to create a coating layer composition. The binder resin provides adhesion and structural integrity, while the dispersant ensures uniform distribution of metal oxide particles. This composite approach overcomes the weak dispersion force of individual metal oxides by creating a synergistic material system where the coating matrix supports and distributes the flame retardant particles effectively.
Solution Approach 2:
The patent introduces a dispersant and binder resin as intermediaries between the metal oxide particles and the coating matrix. These intermediary substances improve the wettability, distribution, and adhesion of metal oxide particles, transforming the weak dispersion characteristic into effective uniform distribution within the coating layer, thereby facilitating ease of manufacture while maintaining non-toxicity.
4Ease of manufacture
If fatty acid-based dispersant is used to secure dispersion force, then dispersion is improved, but thermal shrinkage and electrode adhesion are worsened
Solution Approach 1:
The patent changes the chemical composition parameters of the coating layer by selecting specific types and amounts of binder resin and dispersant that do not adversely affect thermal shrinkage or electrode adhesion. By optimizing the molecular weight, functional groups, and concentration of these additives, the patent achieves adequate dispersion force without the negative effects observed with fatty acid-based dispersants, thus improving electrode adhesion and reducing thermal shrinkage while maintaining manufacturability.
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 gas generating agent effectively prevents combustion and explosion by generating gas, ensuring safety and maintaining battery capacity, while being environmentally friendly and non-toxic.
Implementation Method 1
a porous coating layer including a gas generating agent formed on at least one surface of a porous substrate... the gas generating agent may generate gas by reaction
Implementation Method 2
as the inorganic hydroxide-based flame retardant is less corrosive in processing machines, has excellent electrical insulation... stable within the temperature range for molding and processing of the polymer with a high decomposition temperature
Implementation Method 3
the inorganic hydroxide-based flame retardants can be used in various ways because it has high heat absorption, inhibits combustion so as to lower the temperature of a polymer
Implementation Method 4
a separator having a porous coating layer including an inorganic material formed on at least one surface of a porous substrate... exhibit high ion permeability and high mechanical strength
Data Source
AI summary
A separator including a gas generating agent and a method of manufacturing the same. More particularly, the separator has a porous coating layer including an inorganic material on at least one surface of a porous substrate, wherein the porous coating layer includes a gas generating agent.