Stacked Battery Separator Composition for Safety and Electrolyte Impregnation
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Solution Overview
Problem
Existing non-aqueous electrolyte secondary battery techniques fail to improve safety and discharge characteristics while maintaining electrolyte impregnation properties, leading to increased aging time and decreased productivity.
Innovation Solution
A non-aqueous electrolyte secondary battery design featuring a stacked electrode structure with separators having a substrate and surface layers containing a vinylidene fluoride and hexafluoropropylene unit ratio of 4.2% to 5.8% and an electrolyte solution with a cyclic carbonate ester to chain ester ratio of 0.2 to 0.7, which enhances safety and discharge characteristics without compromising impregnation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat and pressure are applied to edges of adjacent separation films to form sealing parts, then safety is improved, but impregnation property of electrolytic solution decreases and aging time increases
Solution Approach 1:
The patent changes the chemical composition parameters of the separator by incorporating vinylidene fluoride and hexafluoropropylene units in a specific ratio (4.2-5.8%). This compositional modification allows the separator to achieve both safety sealing function and good electrolyte impregnation without requiring excessive heat and pressure treatment, thus resolving the contradiction between safety improvement and productivity maintenance.
2Reliability
If heat and pressure are applied to edges of adjacent separation films to form sealing parts, then safety is improved, but discharge characteristics are not improved
Solution Approach 1:
The patent uses a composite separator structure combining vinylidene fluoride and hexafluoropropylene units with specific mass ratio. This composite material approach provides both the safety sealing function and enhanced discharge characteristics simultaneously, avoiding the need for aggressive heat and pressure treatment that would compromise discharge performance.
3Reliability
If separator surface layers contain vinylidene fluoride and hexafluoropropylene units with specific ratio, then safety and discharge characteristics are improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies local quality by providing surface layers on the separator with specific polymer composition (vinylidene fluoride and hexafluoropropylene units) that differ from the base substrate. This localized compositional modification enhances safety and discharge characteristics at the separator surfaces where electrolyte contact occurs, while maintaining a simpler overall 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 design improves safety and discharge characteristics while maintaining electrolyte impregnation, reducing aging time and increasing productivity by optimizing the adhesion strength and ion permeability of the separators and electrolyte solution.
Implementation Method 1
the first surface layer and the second surface layer include a polymer including a vinylidene fluoride unit and a hexafluoropropylene unit
Implementation Method 2
a non-aqueous electrolyte secondary battery including an electrode body and a non-aqueous electrolytic solution
Data Source
AI summary
A non-aqueous electrolyte secondary battery is provided and includes an electrode body and a non-aqueous electrolytic solution. The electrode body includes a plurality of positive electrodes, a plurality of negative electrodes, and a plurality of separators, and the positive electrodes and the negative electrodes are stacked such that the separators are sandwiched therebetween, and such that the separators are protruded from peripheral edges of the positive electrodes and negative electrodes. Peripheral edges of the separators adjacent to each other with the positive electrode interposed therebetween have contact with each other, and peripheral edges of the separators adjacent to each other with the negative electrode interposed therebetween have contact with each other. The separator includes a substrate, a first surface layer provided on a first surface of the substrate, and a second surface layer provided on a second surface of the substrate. The first surface layer and the second surface layer include a polymer including a vinylidene fluoride unit and a hexafluoropropylene unit. The ratio by mass of the amount of the hexafluoropropylene unit to the total amount of the amount of the vinylidene fluoride unit and the amount of the hexafluoropropylene unit is 4.2% or more and 5.8% or less. The non-aqueous electrolytic solution contains a cyclic carbonate ester and a chain ester, and the ratio by mass of the cyclic carbonate ester to the chain ester is 0.2 or more and 0.7 or less.