Non-Uniform Porosity Separator for Li-Ion Battery Safety
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Solution Overview
Problem
Existing separator technologies for lithium-ion secondary batteries face challenges in maintaining ion permeability while enhancing strength and heat resistance, particularly due to issues with inorganic membrane distribution and adhesion, leading to potential short circuits and reduced battery safety.
Innovation Solution
A separator with a porous body and a particle membrane made of inorganic particles, where the particle membrane has non-uniform porosity in the thickness direction, providing improved strength and maintaining ion permeability through controlled void distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a particle membrane made of inorganic particles is formed on a porous body to enhance strength and heat resistance, then safety and heat resistance are improved, but ion permeability may be reduced due to uniform pore closure
Solution Approach 1:
The particle membrane is designed with non-uniform porosity distribution in the thickness direction, creating different pore densities at different depths. The first surface has higher pore density for ion permeability, while the second surface has lower pore density for strength, resolving the contradiction between ion transport and structural integrity
2Object-generated harmful factors
If the particle membrane has high porosity to maintain ion permeability, then ion transport is improved, but strength and heat resistance are reduced
Solution Approach 1:
Different regions of the particle membrane have different porosity levels tailored to their functional requirements. The region adjacent to the first surface has higher porosity for ion permeability, while the region adjacent to the second surface has lower porosity for strength, allowing both ion transport and mechanical strength to be optimized simultaneously
3Temperature
If inorganic particles are deposited to form a dense membrane for heat resistance, then heat resistance is improved, but adhesion to the porous body deteriorates
Solution Approach 1:
The particle membrane exhibits gradient porosity where the density and particle arrangement vary through the thickness. This gradient structure creates optimal adhesion at the interface with the porous body while maintaining heat resistance in the bulk, resolving the contradiction between adhesion and thermal performance
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 strength and safety of lithium-ion secondary batteries by ensuring effective ion permeability and heat resistance, reducing the risk of short circuits and improving battery performance under harsh conditions.
Implementation Method 1
The particle membrane has a porosity that is non-uniform in the thickness direction thereof, when viewed in the thickness direction
Data Source
AI summary
A method of producing a separator is provided. The method includes providing a particle membrane including inorganic particles on at least one principal surface of a porous body by a vapor-phase process such that the particle membrane has a porosity that is non-uniform in a thickness direction thereof. A method of producing a microporous membrane is also provided.