Nanofiber Battery Separator Coating for Wetting and Low Resistance
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Solution Overview
Problem
Lithium secondary battery separators face issues with high resistance and low wettability with electrolytes, particularly due to the detachment of inorganic particles and the requirement for large amounts of binder polymer, which increases resistance.
Innovation Solution
A separator with an organic/inorganic composite porous layer featuring inorganic particles with a BET specific surface area of 20-75 m2/g, inserted into the voids of a nanofiber scaffold, and a binder polymer content of 2-5 wt%, which reduces the need for excessive binder and enhances wettability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inorganic particles with large specific surface area are used to improve wettability, then wettability with electrolyte is improved, but binder polymer amount increases resulting in increased resistance
Solution Approach 1:
The patent optimizes the BET specific surface area of inorganic particles to a specific range (5-50 m²/g) to achieve the optimal balance between wettability and resistance. This parameter optimization ensures sufficient wettability while minimizing the required binder polymer amount, thus keeping resistance low.
Solution Approach 2:
The patent creates an organic/inorganic composite porous layer by combining inorganic particles with a binder polymer in specific weight ratios (inorganic particles: 90-97 wt%, binder polymer: 3-10 wt%). This composite structure achieves both good wettability and low resistance by optimizing the composition and interaction between organic and inorganic components.
2Temperature
If inorganic particles are used to prevent heat shrinking, then thermal safety is improved, but particle detachment occurs reducing reliability
Solution Approach 1:
The patent optimizes the weight ratio of binder polymer to inorganic particles (3-10 wt%) to achieve sufficient adhesion strength. This parameter optimization ensures that inorganic particles remain firmly attached to the porous substrate while maintaining thermal safety properties, preventing particle detachment during battery operation.
Solution Approach 2:
The patent uses a small amount of binder polymer (3-10 wt%) as a sacrificial component that provides sufficient adhesion strength to prevent particle detachment. The binder polymer acts as a bonding agent that holds inorganic particles firmly on the porous substrate, ensuring long-term reliability.
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 results in a separator with improved wettability and reduced resistance, preventing particle detachment and ensuring thermal safety and electrolyte compatibility.
Implementation Method 1
the organic/inorganic composite porous layer has a structure including the inorganic particles inserted to the voids of the nanofiber scaffold
Implementation Method 2
the present disclosure relates to a separator for a lithium secondary battery having improved wettability with an electrolyte
Data Source
AI summary
A separator and a lithium secondary battery including the same are disclosed herein. In some embodiments, a separator includes a porous polymer substrate; and an organic/inorganic composite porous layer disposed on at least one surface of the porous polymer substrate and including a nanofiber scaffold, inorganic particles and a binder polymer, wherein, in the organic/inorganic composite porous layer, the inorganic particles are present in voids of the nanofiber scaffold, the inorganic particles have a BET specific surface area of 20 m2/g to 75 m2/g, and the binder polymer is present in an amount of 2 wt % to 5 wt % based on the total weight of the organic/inorganic composite porous layer.