Alkaline Battery Separator Paper Crystalline Structure
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Solution Overview
Problem
Conventional separator papers for alkaline batteries face challenges in preventing internal shortages due to dendrite growth and high internal resistance, which reduces electric capacity and high-rate discharge performance, while also occupying excessive volume and increasing internal resistance.
Innovation Solution
A thin separator paper with a crystalline structure comprising both cellulose 1 and cellulose 2, treated with NaOH to achieve a controlled ratio of cellulose 2, is developed, offering high gas tightness and reduced area shrinkage, allowing for increased active material capacity and improved discharge properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separator paper thickness is increased to prevent internal shortages, then reliability improves, but volume occupancy increases and internal resistance increases
Solution Approach 1:
The patent changes the chemical composition parameters of the separator paper by controlling the ratio of alkali-proof cellulose fibers (20-80 wt%) and using specific beating degrees (CSF 0-500 ml), which transforms the physical structure to achieve both thinness and high gas tightness, resolving the contradiction between thickness and effectiveness
Solution Approach 2:
The patent creates a composite fiber structure combining synthetic fibers (vinylon) with alkali-proof cellulose fibers (viscose rayon, linter pulp, mercerized wood pulp, polynosic rayon) in specific ratios, where each component contributes different properties: synthetic fibers provide structural stability while cellulose fibers provide alkali resistance and gas tightness, achieving both reliability and thinness
2Reliability
If separator paper thickness is increased to prevent dendrite contact, then reliability improves, but internal resistance increases
Solution Approach 1:
The patent optimizes the beating degree parameter (CSF 0-500 ml) to control fiber fibrillation and pore structure, creating a dense yet conductive network that provides dendrite protection while maintaining low internal resistance through optimized pore size and distribution
Solution Approach 2:
The patent utilizes controlled porosity in the separator paper structure, where the beating process creates fine fibrils that form a dense network with optimized pore sizes, allowing ionic conduction while physically blocking dendrite growth, thus reducing internal resistance while maintaining reliability
3Volume of stationary object
If separator paper is made thinner to reduce volume, then volume occupancy decreases, but gas tightness decreases
Solution Approach 1:
The patent changes the physical parameters of the paper structure by controlling beating degree (CSF 0-500 ml) and fiber composition ratios, which transforms the fiber network into a dense fibrillar structure that maintains high gas tightness even at thicknesses of 100 μm or less
Solution Approach 2:
The patent employs controlled porous structure through beating treatment, where fine fibrils create a tortuous path for gas penetration, achieving high gas tightness (5-500 minutes/100 ml) in thin separator papers by optimizing pore size, distribution, and connectivity
4Duration of action of stationary object
If conventional mixed fiber paper is used, then durability against electrolyte is sufficient, but pore size is too large
Solution Approach 1:
The patent changes the structural parameters by applying beating treatment (CSF 0-500 ml) that transforms the fiber network into a fine fibrillar structure, reducing pore size from conventional large pores to fine pores that block dendrites while maintaining alkali-proof cellulose fiber content (20-80 wt%) for electrolyte durability
Solution Approach 2:
The patent creates a composite structure where alkali-proof cellulose fibers (providing chemical stability and fine pore formation through beating) are combined with synthetic vinylon fibers (providing mechanical strength and structural stability), achieving both durability and fine pore structure for dendrite prevention
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 new separator paper effectively prevents internal shortages, enhances electric capacity, and reduces internal resistance, enabling improved high-rate discharge performance while minimizing volume occupancy.
Implementation Method 1
the separator paper should not block the ionic conduction
Implementation Method 2
treated with NaOH to achieve a controlled ratio of cellulose 2
Data Source
AI summary
A thin separator paper is provided for separating a positive electrode active material and a negative electrode active material from one another in alkaline battery. The separator paper has high gas tightness, high shortage preventing effect, and low deterioration. The separator paper possesses a crystalline structure in which cellulose 1 and cellulose 2 coexist. A ratio of the cellulose 2 is controlled in relation to the cellulose 1 and the separator paper is made by using an alkali treated pulp beaten from CSF 50 ml to 0 ml, as a raw material. The separator paper has the thickness between 15 μm and 60 μm, the gas tightness between 10 minutes/100 ml and 800 minutes/100 ml, and the area shrinkage rate which is not greater than 2%. Also provided is an alkaline battery containing the separator paper.