Battery Separator Coating for Wrinkle-Free Pin Removal
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Solution Overview
Problem
Thin membrane separators for non-aqueous electrolyte batteries are prone to wrinkling and have poor pin removal properties, leading to issues like shape loss, winding collapse, and deformation during the production of wound batteries.
Innovation Solution
A separator configuration with a porous substrate, an inorganic filler-containing layer on one face, and a thermoplastic polymer-containing layer on the surface, where the dynamic friction coefficients between the separator and stainless steel and a lithium metal oxide-containing electrode satisfy specific ratios, enhancing pin removal properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If thin membrane separators are used to improve battery capacity, then the battery capacity increases, but the separator becomes prone to wrinkling and has poor pin removal properties
Solution Approach 1:
The invention uses a composite structure consisting of a polyolefin microporous membrane base layer combined with a silane crosslinked polymer coating layer. This composite material approach allows the thin separator to maintain both high capacity and excellent pin removal properties, as the silane crosslinked layer provides the necessary friction control while the thin overall structure preserves battery capacity.
Solution Approach 2:
The invention changes the chemical and physical parameters of the separator surface by applying a silane crosslinked polymer coating. This coating modifies the surface friction characteristics and thermal properties, enabling the thin separator to achieve adequate pin removal properties (coefficient of dynamic friction between 0.15-0.45) while maintaining thin membrane structure for high capacity.
2Quantity of substance
If thin membrane separators are used to improve battery capacity, then the battery capacity increases, but the separator is prone to wrinkling
Solution Approach 1:
The silane crosslinked polymer coating layer provides structural reinforcement to the thin polyolefin base layer, preventing wrinkling during the winding process. The coating forms a more rigid surface structure that maintains shape stability while allowing the overall separator to remain thin for high battery capacity.
Solution Approach 2:
The silane crosslinked polymer coating is applied specifically to the surface of the polyolefin microporous membrane, providing localized reinforcement only where needed for wrinkle prevention and friction control, while the bulk of the separator remains thin to maintain high capacity.
3Reliability
If conventional separators are used with good pin removal properties, then the pin removal properties are adequate, but the separator thickness increases reducing battery capacity
Solution Approach 1:
The invention uses a thin film approach with a silane crosslinked polymer coating layer that is thin enough to maintain overall separator thinness for high capacity, yet provides sufficient friction modification for adequate pin removal properties. The coating acts as a flexible surface layer that controls interaction with winding pins without requiring thick separator construction.
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 improves pin removal properties and productivity, allowing for the production of thin membrane separators with excellent performance and increased capacity in energy storage devices.
Implementation Method 1
a coefficient of dynamic friction μ′α between a surface on the porous substrate side and stainless steel (SUS304) or a coefficient of dynamic friction μ′β between a surface on the inorganic filler-containing layer side and a lithium metal oxide-containing face of a predetermined positive electrode f satisfy the following relationship: 0.15 ≤ μ′α/μ′β < 0.65
Data Source
AI summary
[PROBLEM] An object of the present invention is to provide a separator for an energy storage device having excellent pin removal properties when pulling out a pin from a wound body with an electrode, a method for the production of the separator, or an energy storage device including the same.[SOLUTION] Provided is a separator for an energy storage device, including a porous substrate, an inorganic filler-containing layer arranged on only one face of the porous substrate, and a thermoplastic polymer-containing layer arranged on a surface of the inorganic filler-containing layer, wherein a coefficient of dynamic friction μ′α between a surface on the porous substrate side and stainless steel (SUS304) and a coefficient of dynamic friction μ′β between a surface on the inorganic filler-containing layer side and a lithium metal oxide-containing face of a predetermined positive electrode f satisfy the following relationship:μ’α/μ’β<1..