Lithium Ion Battery Separator Coating for Thermal Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium ion batteries face stability and safety issues due to unwanted chemical reactions and thermal shrinkage of separators at high temperatures, which affect their cycling performance and capacity retention.
Innovation Solution
A modifier comprising a mixture of a phosphorus source with a phosphate radical, a trivalent aluminum source, and a metallic oxide is used to form a protective film on current collectors, electrodes, and separators, preventing side reactions and enhancing thermal stability through a clear solution process that includes heating to form AlxMyPO4 or AlxMy(PO3)3 compositions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If AlPO4 particles are dispersed in water and coated on LiCoO2 cathode particles, then thermal stability is improved, but the coating layer becomes non-uniform due to particle agglomeration
Solution Approach 1:
The patent changes the chemical parameters of the dispersion medium from water to organic solvents (NMP, ethanol, acetone, or their mixtures). This parameter change prevents AlPO4 particle agglomeration by ensuring better compatibility between the dispersant and particles, resulting in uniform coating layers while maintaining thermal stability improvements.
Solution Approach 2:
The patent introduces organic dispersants (NMP, ethanol, or acetone) as intermediaries between AlPO4 particles and the coating process. These intermediaries facilitate uniform particle distribution by preventing direct particle-particle contact and agglomeration, enabling homogeneous coating on cathode particles.
2Duration of action of moving object
If the separator is used at high temperatures, then battery operation is maintained, but the separator shrinks or fuses causing low stability
Solution Approach 1:
The patent creates a composite separator structure by coating AlPO4 particles onto the separator surface. This composite material combines the base separator material with thermally stable AlPO4 particles, preventing separator shrinkage and fusion at high temperatures while maintaining operational continuity.
Solution Approach 2:
The patent applies a thin film of AlPO4 coating on the separator surface. This thin protective film acts as a thermal barrier that prevents the separator from reaching its melting point and undergoing dimensional changes, thereby maintaining separator stability during high-temperature operation.
3Reliability
If electrode active materials are coated with AlPO4 particles using water dispersion, then corrosion resistance is improved, but the dispersion is difficult to use on other battery components
Solution Approach 1:
The patent changes the dispersion medium from water to organic solvents (NMP, ethanol, acetone, or their mixtures). This parameter change makes the AlPO4 dispersion compatible with various battery components including current collectors and different electrode materials, while maintaining the corrosion resistance benefits.
Solution Approach 2:
The patent creates a universal coating process using organic dispersants that can be applied to multiple battery components (cathode particles, current collectors, separators). This multi-functional approach allows the same AlPO4-based coating system to protect different components throughout the battery, enhancing versatility.
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 modifier significantly increases the thermal stability and safety of lithium ion batteries by preventing corrosion and shrinkage, maintaining electrochemical performance and capacity retention without compromising conductivity.
Implementation Method 1
A modifier comprising a mixture of a phosphorus source with a phosphate radical, a trivalent aluminum source, and a metallic oxide is used to form a protective film on current collectors, electrodes, and separators
Implementation Method 2
heating to form AlxMyPO4 or AlxMy(PO3)3 compositions
Data Source
AI summary
A method for making a separator of a lithium ion battery is provided. In the method, a modifier, and a porous membrane are provided. The modifier is a mixture of a phosphorus source having a phosphate radical, a trivalent aluminum source, and a metallic oxide provided in a liquid phase solvent. The modifier is coated on a surface of the porous membrane to form a coating layer. The coated porous membrane is dried to form a modifier layer disposed on the surface of the porous membrane.