Aromatic Polyamide Separator Slurry for Porosity-Strength Balance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Aromatic polyamide separators face a challenge in balancing high porosity and mechanical strength, leading to short lifespan and poor safety of lithium batteries due to the mutual influence between porosity and mechanical strength in existing technologies.
Innovation Solution
A slurry for a separator is developed, comprising an aromatic polyamide, a solvent, and a hydrophilic nanofiber, which forms a network-like structure through physical and chemical interactions, increasing mechanical strength and rotational viscosity, thereby achieving high porosity and mechanical strength balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the solvent content in the slurry is increased to improve porosity, then the porosity of the separator is improved, but the mechanical strength of the separator deteriorates
Solution Approach 1:
The patent uses a composite material system consisting of aromatic polyamide as the matrix and hydrophilic nanofibers (cellulose, ceramic, or glass) as reinforcement. This composite structure allows the separator to achieve high porosity (30-90%) while maintaining mechanical strength, as the nanofibers provide structural support within the porous matrix. The nanofibers act as a reinforcing skeleton that prevents collapse of the porous structure under mechanical stress.
Solution Approach 2:
The patent employs porous aromatic polyamide material with controlled porosity of 30-90% to achieve high liquid absorption and retention rates. The porous structure is maintained through the NIPS method while the mechanical strength is preserved through the addition of hydrophilic nanofibers that reinforce the porous matrix without blocking the pores.
2Duration of action of moving object
If the porosity of the separator is increased to improve liquid absorption rate and cycle performance, then the cycle performance is improved, but the safety deteriorates due to decreased mechanical strength
Solution Approach 1:
The composite of aromatic polyamide and hydrophilic nanofibers creates a separator that simultaneously achieves high cycle performance (through high porosity of 30-90%) and high safety (through enhanced mechanical strength). The nanofibers prevent dendrite penetration while maintaining open pore structures for efficient ion transport during cycling.
Solution Approach 2:
The hydrophilic nanofibers are distributed throughout the aromatic polyamide matrix to create localized reinforcement zones. These nanofiber-reinforced regions provide mechanical strength and dendrite resistance, while the surrounding porous matrix maintains high porosity for liquid absorption and ion transport, achieving both cycle performance and safety.
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 solution enhances the cycle life and safety of lithium batteries by improving liquid absorption and retention rates while preventing lithium dendrites from piercing the separator, ensuring consistent thickness and uniform pore distribution.
Implementation Method 1
the hydrophilic nanofiber interacts with the aromatic polyamide polymer to form a network-like structure, the interaction between the hydrophilic nanofiber and the aromatic polyamide polymer includes physical and chemical interactions
Implementation Method 2
the porosity of the aromatic polyamide separators is positively correlated with the solvent content in the slurry, the higher the solvent content, the higher the porosity of the separator prepared by non-solvent induced phase separation (NIPS) method
Implementation Method 3
extracting the solvent from the membrane through a gelation bath to form a porous membrane
Data Source
AI summary
A slurry for a separator includes an aromatic polyamide, a solvent, and an additive including a hydrophilic nanofiber. On the one hand, the hydrophilic nanofiber increases the internal tension of the slurry, thereby increasing the mechanical strength of the final separator. On the other hand, the additive in this disclosure can significantly increase the rotational viscosity of the slurry for a separator, which can further reduce the mass fraction of aramid in the slurry while meeting the lowest requirements of rotational viscosity in casting the separator, If the mass fraction of aramid decreases, the mass fraction of solvent increases, and the porosity of the separator obtained by non-solvent induced phase separation (NIPS) increases. Therefore, the separator made using the additive in this disclosure can obtain both high porosity and high mechanical strength, thereby improving the cycle life and safety performance of a lithium battery.