Flooded Battery Separator Morphology for Lower Resistance and Higher CCA
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Solution Overview
Problem
Enhanced flooded batteries face challenges in reducing internal electrical resistance and increasing cold cranking amps, which limits their performance compared to Absorbent Glass Mat (AGM) batteries.
Innovation Solution
A microporous separator with decreased tortuosity, increased porosity, and improved fillers, such as silica with high silanol groups, is used to create a shish-kebab structure in the polyolefin microporous membrane, reducing electrical resistance and enhancing ion diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional separators are used in enhanced flooded batteries, then manufacturing cost is reduced and ease of manufacture is improved, but electrical resistance remains high and cold cranking amps are limited
Solution Approach 1:
The separator uses a composite structure combining polyolefin matrix with silica particles (40-60 wt%) that have specific surface properties. This composite approach reduces electrical resistance while maintaining manufacturability through established coating and extrusion processes.
Solution Approach 2:
The separator employs a microporous structure with controlled pore size distribution (0.01-10 micrometers) and porosity (30-70%). The porous architecture facilitates ion transport, reducing electrical resistance while allowing standard porous membrane manufacturing techniques to be used.
2Reliability
If separator porosity is increased to reduce electrical resistance, then ion diffusion improves and cold cranking amps increase, but mechanical strength decreases
Solution Approach 1:
Silica particles (40-60 wt%) serve as reinforcement fillers within the polyolefin matrix, providing mechanical strength even at high porosity levels (30-70%). The composite structure prevents the separator from becoming too weak despite the increased pore volume needed for low electrical resistance.
Solution Approach 2:
The separator exhibits varying local properties: the silica particle distribution and pore size (0.01-10 micrometers) are optimized in different regions to balance mechanical strength requirements in some areas with ion transport requirements in others, achieving both high strength and low electrical resistance.
3Reliability
If AGM battery architecture is used to achieve low electrical resistance and high cold cranking amps, then performance is improved, but manufacturing cost increases and sensitivity to overcharging increases
Solution Approach 1:
The patent uses conventional flooded battery components (liquid electrolyte, traditional electrode structures) rather than expensive AGM glass mat materials. This approach achieves comparable cold cranking amps through separator optimization while maintaining the cost advantages and manufacturing simplicity of traditional flooded battery designs.
Solution Approach 2:
The separator parameters (porosity 30-70%, pore size 0.01-10 micrometers, silica content 40-60 wt%, thickness 20-200 micrometers) are specifically tuned to achieve AGM-level performance in a flooded battery system, allowing parameter optimization without changing the fundamental battery architecture or incurring AGM manufacturing costs.
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 results in a 20-30% reduction in electrical resistance and increased cold cranking amps, matching or exceeding the performance of AGM batteries while maintaining mechanical strength and reducing water loss.
Implementation Method 1
a battery separator should permit ionic diffusion between the positive and negative electrodes with the least possible resistance in order to generate a current
Implementation Method 2
EFB systems have similar architecture to traditional flooded lead acid batteries, in which positive and/or negative electrodes are surrounded by a microporous separator and submerged in a liquid electrolyte
Data Source
AI summary
A battery separator has performance enhancing additives or coatings, fillers with increased friability, increased ionic diffusion, decreased tortuosity, increased wettability, reduced oil content, reduced thickness, decreased electrical resistance, and/or increased porosity. The separator in a battery reduces the water loss, lowers acid stratification, lowers the voltage drop, and/or increases the CCA. The separators include or exhibit performance enhancing additives or coatings, increased porosity, increased void volume, amorphous silica, higher oil absorption silica, higher silanol group silica, reduced electrical resistance, a shish-kebab structure or morphology, a polyolefin microporous membrane containing particle-like filler in an amount of 40% or more by weight of the membrane and ultrahigh molecular weight polyethylene having shish-kebab formations and the average repetition periodicity of the kebab formation from 1 nm to 150 nm, decreased sheet thickness, decreased tortuosity, separators especially well-suited for enhanced flooded batteries.