Alkaline Battery Separator Pore Control for Dendrite Resistance
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Solution Overview
Problem
Alkaline battery separators face challenges with processability, mechanical characteristics, and cost due to low basis weight, leading to poor drop resistance and increased risk of short circuits from dendrite generation, necessitating a separator with controlled pore size and improved barrier properties.
Innovation Solution
A blend of polyvinyl alcohol (PVA) and cellulose derivative, such as Tencel, with controlled pore size is developed, where the cellulose is highly fibrillated and combined with PVA, achieving a predetermined pore size for enhanced mechanical integrity and ion transport in alkaline batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If low basis weight separator is used to reduce weight and increase active material, then space savings and discharge performance are improved, but mechanical strength and drop resistance deteriorate
Solution Approach 1:
The patent applies composite materials by combining PVA fibers with cellulose or cellulose derivatives in a blended separator structure. This composite approach allows the separator to achieve both low basis weight and adequate mechanical strength through the synergistic properties of different fiber materials, resolving the contradiction between weight reduction and strength maintenance.
Solution Approach 2:
The patent utilizes porous materials with controlled porosity (30-70%) and specific pore size (1-10 μm) to optimize both weight and mechanical properties. The controlled pore structure provides sufficient mechanical integrity while maintaining low basis weight, enabling the separator to withstand mechanical stresses despite reduced material quantity.
2Weight of moving object
If low count fibers are used to reduce basis weight, then space for active material increases, but processability and mechanical characteristics worsen
Solution Approach 1:
The patent applies parameter changes by optimizing fiber count, fiber length, and porosity parameters within specific ranges. By controlling these parameters, the separator achieves low basis weight while maintaining processability during manufacturing and adequate mechanical characteristics in the final battery product.
3Reliability
If separator porosity is increased to improve ion transport, then ionic conductivity improves, but mechanical integrity and barrier properties worsen
Solution Approach 1:
The patent applies porous materials with controlled pore size (1-10 μm) and porosity (30-70%) to achieve optimal balance between ion transport and mechanical integrity. The controlled pore structure provides sufficient pathways for ion conduction while maintaining the mechanical strength needed to prevent dendrite penetration and short circuits.
4Productivity
If basis weight is reduced to enhance discharge performance, then space for active material increases, but barrier properties and dendrite resistance deteriorate
Solution Approach 1:
The patent applies composite materials combining PVA and cellulose derivatives to achieve low basis weight with enhanced barrier properties. The composite structure provides sufficient mechanical and chemical resistance to prevent dendrite formation and short circuits, even at reduced basis weight, thereby maintaining reliability while improving discharge performance.
Solution Approach 2:
The patent utilizes porous materials with optimized pore size (1-10 μm) and porosity (30-70%) to create an effective barrier against dendrites. The controlled pore structure physically blocks dendrite penetration while allowing efficient ion transport, maintaining barrier properties despite reduced basis weight.
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 provides alkaline battery separators with improved mechanical strength, reduced risk of short circuits, and cost-effective production by maintaining consistent porosity and tortuosity, allowing for efficient ion transport and enhanced discharge performance.
Implementation Method 1
Separators should have good mechanical integrity, chemical inertness, well-defined and consistent porosity and tortuosity in order to uniformly transport the ions between the electrodes
Implementation Method 2
cellulose and its derivatives support absorption properties
Implementation Method 3
Separator papers for alkaline batteries serve as a mechanical barrier between the electrodes to prevent shorting while allowing for ionic transport through the electrolyte in the pores
Data Source
AI summary
An alkaline battery separator is made from a blend of polyvinyl alcohol and a cellulose derivative, and has a controlled pore size.