Lead-Acid Battery Separator Structure for Dendrite and Acid Stratification
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Solution Overview
Problem
Lead acid batteries face issues with acid stratification, dendrite formation, and increased electrical resistance, leading to reduced battery life and potential failure, particularly in deep cycle applications.
Innovation Solution
The development of a novel battery separator with a porous membrane and optional fibrous mat, incorporating rubber and performance-enhancing additives, featuring a unique rib structure to reduce dendrite formation and acid stratification, and optimized for improved wettability and acid diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional porous polyethylene separator is used, then the battery can operate with basic ion passage, but acid stratification and dendrite formation occur leading to reduced battery life
Solution Approach 1:
The patent employs a porous separator structure with controlled porosity (30-70%) to allow ion passage while physically blocking dendrite growth. The porous membrane provides a tortuous path that prevents straight dendrite penetration, and the pore size distribution (0.01-100 micrometers) is optimized to permit electrolyte flow while capturing dendritic structures before they can bridge electrodes.
Solution Approach 2:
The separator is constructed as a composite material combining polyethylene base polymer with silane-modified polysiloxane crosslinking agents and various functional additives. This composite structure provides enhanced mechanical strength, thermal stability, and chemical resistance while maintaining porosity. The crosslinked network prevents separator deformation that could facilitate dendrite growth.
2Reliability
If a conventional porous polyethylene separator is used, then the battery structure is simple, but electrical resistance increases and acid diffusion is poor
Solution Approach 1:
The patent systematically adjusts critical parameters including porosity (30-70%), pore size distribution (0.01-100 micrometers), crosslinking density (5-50 wt% crosslinking agent), and additive concentrations to optimize electrical resistance and acid diffusion. The molecular weight of polyethylene (10,000-1,000,000 g/mol) and silane content (1-10 wt%) are controlled to achieve desired separator properties that balance ion conductivity with structural integrity.
3Reliability
If the separator lacks rubber and performance-enhancing additives, then the manufacturing process is simple, but oxidation stability and wettability are insufficient
Solution Approach 1:
The patent incorporates functional additives at specific locations and concentrations within the separator structure. Rubber components (1-20 wt%) are distributed throughout the matrix to provide localized oxidation resistance, while wetting agents (0.1-5 wt%) are positioned at pore surfaces to enhance electrolyte wettability. This localized functional distribution achieves high performance without requiring complex multi-layer construction.
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 effectively mitigates dendrite growth, enhances acid mixing, and reduces electrical resistance, thereby extending battery life and improving performance in deep cycle applications.
Implementation Method 1
ions may pass therethrough between the positive and negative electrodes or plates
Implementation Method 2
enhances acid mixing
Implementation Method 3
mitigates the formation of dendrites
Implementation Method 4
enhances acid mixing
Implementation Method 5
improving acid diffusion
Implementation Method 6
reduces electrical resistance
Implementation Method 7
increasing wettability; lowering wet out time with electrolyte
Data Source
AI summary
Disclosed herein are improved separators for lead acid batteries. The separators may include a porous membrane, a rubber, and at least one performance enhancing additive, positive and/or negative ribs, and/or lowered acid leachable total organic carbon.