Polyvinyl Alcohol Separator for Nonaqueous Cells
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Solution Overview
Problem
Nonaqueous cell separators face challenges in achieving a balance between strength properties, thickness, and air permeability, with existing materials like glass fiber papers and beaten cellulose papers failing to meet these requirements effectively.
Innovation Solution
A fiber sheet separator comprising polyvinyl alcohol fibers with specific fiber breaking temperatures, combined with glass fibers and cellulose fibers, is developed to achieve enhanced strength, reduced thickness, and improved air permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If glass fibers or beaten regenerated cellulose are used as separator material to achieve determined strength properties, then the separator thickness becomes large, but this reduces air permeability and increases cell resistance
Solution Approach 1:
The invention uses a composite fiber sheet comprising glass fibers (20-80 wt%), beaten regenerated cellulose fibers (10-70 wt%), and polyvinyl alcohol fibers (5-30 wt%). This composite structure combines the high strength and heat resistance of glass fibers with the bonding capability of PVA fibers, achieving both mechanical strength and thinness without sacrificing air permeability
2Temperature
If glass fibers are used as separator material to achieve heat resistance and fine fiber structure, then self-bondability is poor, but this reduces aggregate strength
Solution Approach 1:
The invention introduces polyvinyl alcohol fibers as a binder that mediates between glass fibers. The PVA fibers provide self-bondability through hydrogen bonding and entanglement, while the glass fibers provide heat resistance and structural integrity. The beaten regenerated cellulose fibers further enhance the bonding network, creating a synergistic composite 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 separator achieves strong bonding between fibers, maintaining strength while allowing for low resistance and increased air permeability, thereby improving the performance and capacity of nonaqueous cells.
Implementation Method 1
the fiber A having a fiber breaking temperature in heated water of lower than 100°C and higher than 85°C
Implementation Method 2
capable of being fine fibers and regenerated cellulose is capable of being refined or beaten
Implementation Method 3
to have air permeability (porousness, ion permeability)
Implementation Method 4
a determined performance of strength properties (such as tensile strength and piercing strength), as well as to be small in thickness and to have air permeability (porousness, ion permeability)
Implementation Method 5
glass fibers have heat resistance and endurance
Data Source
AI summary
Provided are a separator for a nonaqueous cell that has air permeability and is small in thickness while maintaining strength properties; and a nonaqueous cell having this separator. The separator includes a fiber sheet in which a polyvinyl alcohol fiber is incorporated in a proportion of 30% or more by mass (based on the fiber sheet). The fiber has a fiber breaking temperature in heated water of lower than 100°C and higher than 85°C.