Battery Separator Coating Roughness for Heat and Ion Transport
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing multilayer separators for secondary batteries face challenges in achieving a balance between mechanical and chemical stability, while maintaining performance characteristics such as permeability, wettability, and impregnation, often resulting in increased thickness and reduced performance.
Innovation Solution
A separator comprising a porous substrate with an inorganic particle layer having a surface roughness (Ra) of 180 nm to 230 nm, which enhances uniform lithium ion migration, suppresses side reactions due to moisture, and improves heat resistance, charge/discharge characteristics, and life characteristics of the battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multilayer separator is formed by laminating a porous polymer with a coating layer of binder and inorganic particles, then mechanical stability and chemical stability are improved, but thickness is increased and performance characteristics such as permeability, wettability, and impregnation are reduced
Solution Approach 1:
The patent applies a thin inorganic particle layer (1-10 μm) on the porous substrate surface, creating a thin film structure that provides mechanical and chemical stability without significantly increasing overall thickness. This thin film approach maintains the underlying porous structure's permeability and wettability while adding protective functionality.
Solution Approach 2:
The patent uses a porous substrate as the base layer and incorporates a porous inorganic particle layer with controlled porosity. The porous structure allows ion transport while the inorganic particles provide stability, resolving the contradiction between stability enhancement and permeability maintenance.
2Temperature
If the thickness of the separator is increased to improve mechanical stability, then heat resistance is improved, but permeability and charge/discharge characteristics are reduced
Solution Approach 1:
The patent creates a composite structure combining a porous polymer substrate with an inorganic particle layer. This composite approach provides heat resistance from the inorganic particles while maintaining permeability through the porous structure, avoiding the need to increase overall thickness.
Solution Approach 2:
The patent applies the inorganic particle layer only on the surface of the porous substrate rather than throughout the entire separator thickness. This localized approach provides heat resistance where needed (at the electrode interface) while preserving the bulk porous structure's permeability and ion transport characteristics.
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 proposed separator design achieves excellent heat resistance and maintains superior charge/discharge performance and life characteristics of the battery, while maintaining appropriate air permeability and moisture content, thus addressing the limitations of existing multilayer separators.
Implementation Method 1
the inorganic particle layer has a surface roughness (Ra) of 180 nm to 230 nm, thereby uniform migration of lithium ions is enhanced
Implementation Method 2
side reactions due to moisture are suppressed
Implementation Method 3
excellent heat resistance
Data Source
AI summary
Separator for a secondary battery and secondary battery comprising the separator. The separator comprises a porous substrate, and an inorganic particle layer on at least one surface of the porous substrate, wherein the inorganic particle layer has a surface roughness (Ra) of 180 nm to 230 nm. The separator improves heat resistance, charge/discharge characteristics, and life characteristics of the secondary battery.