Alkaline Battery Separator Pore Structure for Short-Circuit Shielding
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Solution Overview
Problem
Conventional alkaline battery separators face challenges in achieving a balance between sufficient shielding properties to prevent internal short-circuits and high liquid retention, particularly due to limitations in controlling pore diameter and fiber orientation during manufacturing.
Innovation Solution
A wet nonwoven separator composed of alkali-resistant cellulose and synthetic fibers, with a binder component, is developed, featuring a controlled average pore diameter of 1-10 µm and maximum pore diameter of 20-60 µm, optimized through specific fiber blending and refining processes to enhance shielding and liquid retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pore diameter of the separator is reduced to improve shielding property, then internal short-circuit prevention is enhanced, but liquid retention capability deteriorates
Solution Approach 1:
The separator is divided into multiple layers with different functions: a first nonwoven fabric layer with larger pores for liquid retention, and a second nonwoven fabric layer with smaller pores for shielding. This segmentation allows each layer to optimize its specific function without compromising the other, resolving the contradiction between liquid retention and shielding property.
Solution Approach 2:
Different regions of the separator structure are assigned different pore sizes and material properties. The first layer uses hydrophilic cellulose fibers with larger pores to retain electrolyte, while the second layer uses hydrophobic synthetic fibers with smaller pores to block dendrites. This local differentiation of properties allows simultaneous optimization of both liquid retention and shielding capabilities.
2Reliability
If fibrillated cellulose fibers are used to increase denseness, then dendrite prevention is improved, but manufacturing complexity increases
Solution Approach 1:
The patent uses conventional, readily available nonwoven fabrics that can be easily manufactured through standard wet-laying processes. Instead of requiring complex fibrillation treatments, the invention employs commercially available materials with inherent suitable properties, significantly simplifying the manufacturing process while maintaining effective dendrite prevention through the layered structure.
Solution Approach 2:
The separator combines two different nonwoven fabric materials with complementary properties: hydrophilic cellulose-based fabric for liquid retention and hydrophobic synthetic fiber fabric for mechanical strength and dendrite blocking. This composite structure achieves superior dendrite prevention without requiring complex fibrillation processes, as each material contributes its inherent advantages.
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 effectively improves the reliability of preventing internal short-circuits and maintains excellent liquid retention, enabling better discharging characteristics and higher discharge capacity in alkaline batteries.
Implementation Method 1
a separator for an alkaline battery according to claim 1 is characterized by comprising a wet nonwoven fabric which contains at least alkali-resistant cellulose fibers and alkali-resistant synthetic fibers, and is bound by a binder component; wherein an average pore diameter of the wet nonwoven fabric is 1 to 10 μm
Implementation Method 2
long time retaining of a sufficient amount of electrolytic solution to generate an electrogenic reaction, and no inhibition of ion conduction
Data Source
Figure 1
AI summary
The present invention provides a separator for alkaline batteries and an alkaline battery improving reliability of prevention in internal short-circuits, and having good liquid retention and shielding property. To achieve this, the separator for alkaline batteries is made from a wet nonwoven fabric which contains at least alkali-resistant cellulose fibers and alkali-resistant synthetic fibers bound using a binder component; wherein an average pore diameter of the wet nonwoven fabric is 1 to 10 pm. Moreover, the separator for alkaline batteries uses the wet nonwoven fabric having a maximum pore diameter of 20 to 60 pm, a liquid retention rate of 400 to 700% during immersion in a 40% by mass KOH solution, and a swelling ratio of 30 to 45% during immersion in a 40% by mass KOH solution.