Separator Binder Core-Shell Coating for Thermal Stability
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Solution Overview
Problem
Lithium-ion secondary batteries face stability issues due to the use of non-aqueous electrolyte solutions, which can lead to unexpected fires, especially as the technology shifts towards larger batteries for electric vehicles and energy storage systems, requiring improved thermal and mechanical stability in battery separators.
Innovation Solution
A method for manufacturing a binder for secondary battery separators involving a two-step polymerization process to form a core-shell structured binder, incorporating ceramic particles for enhanced stability, where the first polymerization forms a chain-type particle and the second polymerization creates an emulsion particle, chemically bonding them for improved thermal and mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If non-aqueous electrolyte solutions are used in lithium-ion secondary batteries, then high storage capacity and excellent charging/discharging properties are achieved, but thermal stability deteriorates and fire risk increases
Solution Approach 1:
A coating layer comprising ceramic particles (alumina, boehmite, silica, titania, zirconia, magnesia, or their combinations) is applied to the separator as an intermediary barrier. This coating layer physically separates the non-aqueous electrolyte from the separator substrate, preventing direct thermal interactions while allowing ionic conduction, thus maintaining high storage capacity while improving thermal stability and reducing fire risk.
Solution Approach 2:
The separator is constructed as a composite structure combining the base separator substrate with a coating layer of ceramic particles. This composite material approach leverages the high ionic conductivity and electrochemical stability of ceramics to enhance thermal stability while preserving the energy storage performance provided by the non-aqueous electrolyte system.
2Quantity of substance
If the battery size is increased for electric vehicles and energy storage systems, then energy storage capacity is improved, but thermal stability and mechanical stability deteriorate
Solution Approach 1:
The ceramic particle coating serves as a thermal barrier and structural stabilizer that scales effectively with battery size. As batteries increase in capacity for electric vehicles and energy storage systems, this coating layer provides proportional thermal management benefits, preventing heat accumulation and maintaining mechanical integrity throughout the larger battery structure.
3Reliability
If a coating layer is applied to the separator to improve thermal stability, then fire risk is reduced, but air permeability may deteriorate
Solution Approach 1:
The coating layer is designed with a porous structure comprising ceramic particles that provide thermal stability while maintaining adequate porosity for air and electrolyte penetration. The porous morphology allows ionic conduction and air permeability to be preserved even with the presence of the thermal barrier coating.
Solution Approach 2:
The coating layer applies different properties to different regions: ceramic particles provide thermal stability in areas requiring heat resistance, while the porous structure and particle spacing maintain permeability in areas requiring ionic and air flow. This localized quality distribution resolves the contradiction between thermal protection and permeability.
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 method results in a secondary battery separator with improved thermal and mechanical stability, enhanced air permeability, and uniform electrolyte distribution, leading to increased lifespan and performance of lithium-ion batteries.
Implementation Method 1
performing a first polymerization on a first monomer to form a precursor solution including a chain-type particle
Implementation Method 2
adding a second monomer to the precursor solution and performing a second polymerization to form an emulsion particle on the chain-type particle. In an embodiment, the second polymerization may include an emulsification polymerization in which the chain-type particle acts as an emulsifier
Implementation Method 3
the chain-type particle and the emulsion particle may be chemically bonded
Data Source
AI summary
Provided is a method for manufacturing a binder for coating a secondary battery separator, wherein the method may include performing a first polymerization on a first monomer to form a precursor solution including a chain-type particle, and adding a second monomer to the precursor solution and performing a second polymerization to form an emulsion particle on the chain-type particle. In an embodiment, the second polymerization may include an emulsification polymerization in which the chain-type particle acts as an emulsifier.