Battery Separator Surface Roughness for Heat Resistance and Ion Flow
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Solution Overview
Problem
Existing battery separators face challenges in achieving optimal heat resistance, charge/discharge characteristics, and lifespan due to issues with permeability, wettability, and impregnation, often resulting in performance degradation.
Innovation Solution
A separator for electrochemical devices, such as secondary batteries, comprising a porous substrate with an inorganic particle layer on its surface, where the inorganic particle layer has a specific surface roughness (Ra) of 100 nm to 160 nm, enhancing ion migration and suppressing side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multilayer separator or coating layer with binder and inorganic particles is used to improve separator characteristics, then heat resistance and stability are improved, but thickness increases and battery performance degrades due to low permeability, decreased wettability, and reduced impregnation
Solution Approach 1:
The patent employs a porous inorganic particle layer formed directly on the porous substrate without using organic binders. The porous structure maintains high permeability for ion transport while the inorganic particles provide heat resistance and stability. The pore structure allows electrolyte penetration and ion migration, resolving the contradiction between stability improvement and permeability maintenance.
Solution Approach 2:
The patent creates a composite structure by forming an inorganic particle layer on the porous substrate. This composite design combines the mechanical properties of the substrate with the thermal stability of inorganic particles, achieving both heat resistance and permeability without requiring organic binders that would block pores and reduce wettability.
2Reliability
If separator thickness is increased to improve mechanical and chemical stability, then stability is improved, but battery performance degrades due to reduced ion migration efficiency
Solution Approach 1:
The porous inorganic particle layer provides mechanical stability through the interlocked particle structure while maintaining chemical stability through inorganic material properties. The porous structure ensures efficient ion migration pathways, allowing the separator to achieve both stability and fast ion transport without increasing thickness.
Solution Approach 2:
The inorganic particle layer is applied locally on the separator surface where heat resistance and stability are most needed, rather than increasing the overall thickness of the separator. This localized approach provides stability enhancement without compromising ion migration efficiency in the bulk separator 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 proposed separator exhibits excellent heat resistance and maintains superior charge/discharge characteristics and lifespan, ensuring stable battery performance by optimizing ion migration and reducing side reactions.
Implementation Method 1
the inorganic particle layer has a surface roughness (Ra) of 100 nm to 160 nm
Implementation Method 2
a porous substrate
Implementation Method 3
prevent a physical contact between a negative electrode and a positive electrode
Data Source
Figure 1
AI summary
Embodiment of the present disclosure is to a separator for an electrochemical device comprising a porous substrate, and an inorganic particle layer comprising inorganic particles on or above at least one surface of the porous substrate, wherein the inorganic particle layer has a surface roughness (Ra) of 100 nm to 160 nm. The separator according to an example embodiment may improve heat resistance, charge/discharge characteristics, and life characteristics of a battery, by having the above surface roughness.