Glass Fiber Separator for Lead-Acid Battery PSOC
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Solution Overview
Problem
Lead-acid batteries used in idling stop vehicles experience reduced lifespan due to frequent partial state of charge cycling, leading to increased lead sulfate formation and reduced charge acceptance, which limits their power and energy performance and lifespan.
Innovation Solution
The use of nonwoven fiber mats with a conductive surface and acid-resistant binder to enhance electron flow and wettability, reinforcing the battery plates and separator, and incorporating a mixture of coarse and fine glass fibers with silane sizing to improve acid resistance and wicking behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If lead-acid batteries are used in idling stop vehicles with frequent startup cycles, then the battery must provide high power output, but the charge acceptance deteriorates due to partial state of charge cycling
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition and physical structure of the battery components. Specifically, it uses a glass fiber mat with controlled porosity (30-70%) and specific surface area (500-1500 cm²/g), along with optimizing the electrolyte composition and plate structure, to enable faster charging rates while maintaining high power output capability during frequent startup cycles
Solution Approach 2:
The patent employs composite materials by combining glass fibers with specific treatments and coatings to create a mat structure that provides both mechanical reinforcement and enhanced electrochemical performance. The glass fiber mat is combined with conductive materials and electrolyte to create a composite structure that improves both power delivery and charge acceptance simultaneously
2Power
If the battery operates in partial state of charge conditions, then the power and energy performance is reduced, but the lifespan deteriorates due to repeated charging/discharging in insufficiently charged state
Solution Approach 1:
The patent converts the harmful effect of partial state of charge cycling into a beneficial outcome by using the glass fiber mat structure to manage lead sulfate formation. The mat's porosity and surface properties allow controlled crystallization of lead sulfate that prevents harmful coarsening while maintaining electrical conductivity, thus transforming the detrimental PSOC effect into a mechanism that extends battery lifespan
Solution Approach 2:
The patent changes the physical and chemical parameters of the battery components to optimize performance under PSOC conditions. By controlling the glass fiber diameter distribution (6-13 μm), porosity, and electrolyte composition, the battery maintains better electrochemical activity and reduces irreversible lead sulfate accumulation, thereby improving both power performance and lifespan under partial state of charge operation
3Reliability
If lead sulfate forms on the negative plate during discharge, then the charge acceptance improves by preventing coarsening, but the internal resistance increases due to impervious layer formation
Solution Approach 1:
The patent uses porous glass fiber mat material with controlled porosity (30-70%) and pore size distribution to manage lead sulfate formation. The porous structure allows electrolyte penetration and maintains ion transport pathways even when lead sulfate forms, preventing the creation of impervious layers while still accepting charge effectively. The porosity enables the mat to accommodate lead sulfate crystals without blocking electrical conductivity
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 improves charge acceptance, reduces voltage drop during cranking cycles, and extends the battery's lifespan by maintaining electron flow pathways and reducing lead sulfate formation, thus enhancing the battery's overall performance and durability.
Implementation Method 1
The nonwoven fiber mats described herein may improve the charge acceptance of a lead-acid battery in addition to reinforcing the battery's plates or electrodes. The non-woven mats described herein may also offer a significant improvement (decrease) of the voltage drop when operated in cranking cycles at low operating temperatures
Implementation Method 2
The plurality of second glass fibers include a silane material coating or sizing. The silane sizing of glass fibers may improve the acid resistance of the fibers
Implementation Method 3
The nonwoven fiber mat further include a conductive material that is disposed on at least one surface of the nonwoven fiber mat or throughout the nonwoven fiber mat such that when the nonwoven fiber mat is positioned adjacent the positive or negative electrode, the conductive material contacts the positive or the negative electrode
Data Source
Figure 1~2
Figure 3A~3C
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AI summary
Embodiments of the invention provide a lead-acid battery having a positive electrode, a negative electrode, and a separator positioned between the electrodes to electrically insulate the electrodes. Battery includes a nonwoven fiber mat positioned adjacent an electrode. Mat includes a mixture of first glass fibers having diameters between 8 µm to 13 µm and second glass fibers having diameters of at least 6 µm and a silane sizing. An acid resistant binder bonds the glass fibers to form mat. A wetting component is applied to increase the wettability such that mat exhibits an average water wick height of at least 1.0 cm after exposure to water for 10 minutes. A conductive material is disposed on a surface of mat such that when mat is adjacent an electrode, the conductive material contacts the electrode. An electrical resistance of less than 100,000 ohms per square enables electron flow about mat.