Flooded Lead-Acid Battery Separators for Acid Stratification Control
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Solution Overview
Problem
Conventional flooded lead-acid batteries experience acid stratification when operating in a partial state of charge, leading to reduced battery performance and shorter lifespan due to uneven acid distribution, which is not effectively addressed by existing technologies like VRLA AGM batteries that are more expensive and sensitive to overcharging.
Innovation Solution
The use of optimized separators with specific surface characteristics, such as serrated or dimpled ribs, that enhance acid mixing and circulation within the battery, preventing stratification without the need for mechanical acid mixing systems, and are made from materials like ultrahigh molecular weight polyethylene with silica and processing oil, improving acid uniformity and battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional separators are used in flooded lead-acid batteries operating in partial state of charge, then the battery structure remains simple and cost-effective, but acid stratification occurs leading to reduced battery performance and shorter lifespan
Solution Approach 1:
The separator incorporates three-dimensional surface features including ribs, protrusions, and dimples that create curved surfaces. These curved features disrupt the linear flow of electrolyte and promote turbulent mixing, preventing acid stratification while maintaining the simplicity and cost-effectiveness of flooded lead-acid batteries
Solution Approach 2:
The separator acts as an intermediary element between the positive and negative electrodes, with its specially designed surface features serving as a mixing mechanism. The ribs and dimples on the separator surface create eddy currents and enhance convection in the electrolyte, facilitating uniform acid distribution without requiring external mechanical mixing systems
2Object-generated harmful factors
If VRLA AGM batteries are used to prevent acid stratification, then acid mixing is improved, but the cost increases and the battery becomes more sensitive to overcharging
Solution Approach 1:
The separator features localized three-dimensional surface structures (ribs, protrusions, dimples) at specific positions and orientations. These local modifications create targeted mixing zones that effectively prevent acid stratification, achieving VRLA AGM-level performance while maintaining the simpler and less expensive flooded battery construction
Solution Approach 2:
The invention changes the surface geometry parameters of the separator by incorporating ribs with specific heights, spacings, and angles, as well as dimples with defined depths and distributions. These parameter modifications enhance electrolyte mixing efficiency, allowing flooded batteries to achieve performance comparable to more expensive VRLA AGM systems
3Object-generated harmful factors
If the battery operates in overcharge state with gas bubble generation, then acid mixing is enhanced, but the battery cannot maintain proper acid distribution when operating in partial state of charge
Solution Approach 1:
The separator's three-dimensional surface features are pre-configured to create mixing zones that actively promote electrolyte circulation. This preliminary structural design ensures that acid mixing occurs continuously during operation in partial state of charge, eliminating the need to rely on gas bubble generation from overcharging to achieve proper acid distribution
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 improved separators significantly reduce acid stratification and enhance battery performance, achieving performance comparable to or exceeding that of VRLA AGM batteries while maintaining the cost-effectiveness of flooded lead-acid batteries, with improved acid mixing and circulation that extends battery life and efficiency.
Implementation Method 1
optimized separators with specific surface characteristics, such as serrated or dimpled ribs, that enhance acid mixing and circulation within the battery
Implementation Method 2
made from materials like ultrahigh molecular weight polyethylene with silica and processing oil, improving acid uniformity and battery performance
Data Source
AI summary
Improved battery separators are disclosed herein for use in flooded lead-acid batteries, and in particular enhanced flooded lead-acid batteries. The improved separators disclosed herein provide for enhanced electrolyte mixing and substantially reduced acid stratification. The improved flooded lead-acid batteries may be advantageously employed in applications in which the battery remains in a partial state of charge, for instance in start/stop vehicle systems. Also, improved lead-acid batteries, such as flooded lead-acid batteries, improved systems that include a lead-acid battery and a battery separator, improved battery separators, improved vehicles including such systems, and/or methods of manufacture and/or use may be provided.