Aromatic Polyamide Porous Membrane for Lithium-Ion Battery Thermal Stability
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Solution Overview
Problem
Current lithium-ion battery separators, primarily made of polyolefin, lack high heat resistance, uniformity, gas permeability, and electrochemical oxidation resistance, which limits their performance and safety, especially in high-energy density applications.
Innovation Solution
Aromatic polyamide porous membranes with a uniform three-dimensional network structure and controlled pore size distribution are developed, using a method involving an aromatic polyamide solution extrusion and gelling process to create membranes with symmetrical surfaces and improved porosity, gas permeability, and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polyolefin separators are used in lithium-ion batteries, then the manufacturing cost is low and ease of manufacture is improved, but heat resistance, electrochemical oxidation resistance, and electrolyte absorption performance deteriorate
Solution Approach 1:
The patent uses aromatic polyamide fibers as a coating layer on the polyolefin separator substrate, creating a composite structure that combines the manufacturing advantages of polyolefin with the high heat resistance and electrochemical stability of aromatic polyamide, thereby resolving the contradiction between ease of manufacture and reliability
Solution Approach 2:
The aromatic polyamide coating is designed with controlled porosity (30-80%) and specific pore size distribution (0.01-10 μm) to maintain electrolyte absorption performance and ion transport while providing high heat resistance, addressing the contradiction between porosity and thermal stability
2Reliability
If aromatic polyamide is used as separator material, then heat resistance and electrochemical oxidation resistance are improved, but gas permeability deteriorates due to dense cortical structure
Solution Approach 1:
The patent creates a porous aromatic polyamide coating layer with controlled porosity (30-80%) and pore size (0.01-10 μm) that allows sufficient gas permeability and electrolyte transport while maintaining the high heat resistance inherent to aromatic polyamide materials
Solution Approach 2:
The coating layer is designed with non-uniform pore size distribution, having different pore sizes at different locations, with larger pores (0.1-10 μm) providing gas permeability pathways and smaller pores (0.01-1 μm) maintaining structural integrity and heat resistance
3Quantity of substance
If aromatic polyamide porous membrane is prepared by conventional NIPS method, then porosity is improved, but surface structure uniformity deteriorates due to dense cortical structure formation
Solution Approach 1:
The patent controls the phase separation process by adjusting parameters including solvent type (NMP, DMF, or DMSO), polymer concentration (10-30%), and coagulation bath temperature (0-50°C) to achieve uniform porous structure without dense cortical layer formation, thereby improving both porosity and surface uniformity
4Quantity of substance
If separator thickness is reduced to increase energy density, then battery energy density is improved, but mechanical strength and safety performance deteriorate
Solution Approach 1:
The aromatic polyamide coating layer provides enhanced mechanical strength and thermal stability to the thin separator, enabling reduced thickness (15-30 μm) while maintaining sufficient strength and safety performance through the synergistic composite structure
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 aromatic polyamide porous membranes enhance the thermal stability and safety of lithium-ion batteries, allowing for higher energy density and improved thermal runaway temperature, while maintaining excellent gas permeability and electrochemical performance.
Implementation Method 1
the separator is prepared in a process of converting a continuous phase polymer solution into a continuous phase three-dimensional macromolecular network gel
Implementation Method 2
After absorbing the electrolyte, the separator could isolate the positive electrode from the negative electrode to prevent short circuit and meanwhile allow the mobility of the lithium ions
Implementation Method 3
the separator with excellent performance plays an important role in improving the overall performance of the battery
Data Source
AI summary
The present disclosure provides an aromatic polyamide porous membrane having a uniform internal structure. The internal structure of the membrane is a three-dimensional network porous structure with micron-sized pores. The aromatic polyamide porous membrane of the present disclosure has good thermal stability and is especially suitable for a high energy density lithium-ion power battery, and greatly improves the thermal runaway temperature of the battery. The present disclosure further provides a method for preparing the membrane and a lithium secondary battery having the membrane.