Battery Separator Adhesive Layer Balancing Antistatic and Electrode Adhesion
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Solution Overview
Problem
Conventional separators with a polyvinylidene fluoride (PVDF) layer face challenges in maintaining adhesiveness to electrodes due to static electricity issues, which are exacerbated by the use of surfactants intended to prevent static, leading to decreased handleability and battery performance.
Innovation Solution
A separator for non-aqueous secondary batteries featuring a porous substrate with an adhesive layer containing a polyvinylidene fluoride type resin and lithium imide salt, which prevents static electricity while maintaining adhesiveness, using lithium bis(trifluoromethanesulfonyl)imide or lithium bis(pentafluoroethanesulfonyl)imide, and optionally a heat-resistant layer with an inorganic filler.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a PVDF layer is provided on the separator to prevent static electricity, then handleability is enhanced, but adhesiveness to electrode is lowered
Solution Approach 1:
The invention applies different functional properties to different regions of the separator structure. The PVDF layer is localized on the outer surface to provide antistatic properties, while the inner surface maintains high adhesiveness for electrode bonding. This spatial differentiation of properties allows the separator to simultaneously achieve good handleability and strong electrode adhesion without compromise.
2Object-affected harmful factors
If a surfactant is used to reduce static electricity, then electrostatic propensity is reduced, but adhesiveness between adhesive layer and electrode is lowered
Solution Approach 1:
The invention extracts and removes the harmful surfactant component from the separator system entirely. Instead of using surfactants to manage static electricity, the patent employs an alternative approach by controlling the PVDF layer composition and structure, thereby eliminating the need for surfactants and preserving the adhesive layer's bonding capability to the electrode.
3Ease of operation
If a layer containing PVDF is provided on the separator to prevent static electricity, then handleability is enhanced, but conveyance performance and yield decrease due to adsorption of foreign substances
Solution Approach 1:
The PVDF layer is strategically positioned and controlled in thickness to provide antistatic properties only where needed on the separator surface, while maintaining sufficient porosity and appropriate composition to prevent excessive foreign substance adsorption. This localized application with controlled properties balances handleability improvement with maintenance of conveyance performance and manufacturing yield.
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 adhesiveness to electrodes, prevents static electricity, and improves battery characteristics by balancing antistatic performance with adhesive strength, resulting in improved handleability and battery performance.
Implementation Method 1
PVDF has a property of being susceptible to static electricity... the separator contains a lithium imide salt
Implementation Method 2
an adhesive layer that is provided on at least one side of the porous substrate and that contains a polyvinylidene fluoride type resin... adhesiveness between an electrode and a separator
Data Source
AI summary
An embodiment of the present invention provides a separator for a non-aqueous secondary battery, including a porous substrate; and an adhesive layer that is provided on at least one side of the porous substrate and that contains a polyvinylidene fluoride type resin, in which the separator contains a lithium imide salt.