Wettable Polymer Fiber Sheet for Porous Battery Separators
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current lead-acid battery separators face challenges in achieving high porosity, instant wettabilty, and durability while avoiding the use of hazardous solvents, and they are costly for 'start-stop' applications, with existing materials being difficult to integrate into production processes effectively.
Innovation Solution
A polymer fiber sheet is developed with a fiber modifying agent that acts as both a plasticizer and surface modifying agent, ensuring high porosity, tensile strength, and sustained wettability, which can be densified and embossed for specific properties, and is resistant to thermal degradation and sulfuric acid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional solvents like TCE and hexane are used for extracting process oil, then extraction efficiency is improved, but health and safety risks increase
Solution Approach 1:
The patent replaces hazardous solvents with water, eliminating the need for expensive solvent recovery systems and safety infrastructure. Water is used as a disposable, safe medium that can be easily removed through drying, achieving both cost reduction and safety improvement
Solution Approach 2:
The invention changes the fundamental parameter of the extraction medium from organic solvent to water. This parameter change eliminates toxicity and flammability while maintaining extraction capability through appropriate process optimization
2Productivity
If the thickness of separator products is reduced, then production speed is improved, but extraction and drying times increase
Solution Approach 1:
By using water instead of slow-evaporating organic solvents, the drying process becomes much faster and more efficient. Water can be rapidly removed through conventional drying methods, eliminating the time bottleneck in the production process
Solution Approach 2:
The water-based extraction method allows the process to rush through the extraction and drying stages much faster than traditional solvent-based methods, particularly benefiting thin separator products where time is critical
3Volume of stationary object
If glass fibers are used to achieve high porosity, then porosity is improved, but mechanical properties and production integration deteriorate
Solution Approach 1:
The patent creates a composite fiber mat combining organic fibers (providing mechanical strength) with inorganic porous particles (providing porosity). This composite structure achieves both high porosity and good mechanical properties, resolving the trade-off between the two characteristics
Solution Approach 2:
The invention applies different materials for different functions: organic fibers provide the structural framework for mechanical strength, while inorganic particles create the porous network for electrolyte penetration. Each material performs its specialized function optimally
4Strength
If synthetic polymer fibers are mixed with glass mat, then mechanical properties are improved, but production integration difficulty increases
Solution Approach 1:
The patent merges the production of organic fibers and inorganic particle incorporation into a single extrusion process. The fiber mat is formed and porous particles are incorporated simultaneously, eliminating the need for separate production steps and improving manufacturing integration
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 polymer fiber sheet maintains instant and sustained wettability after multiple washing and drying cycles, exhibits high porosity and tensile strength, and can be tailored for specific applications, such as lead-acid batteries, without the need for hazardous solvents, improving manufacturing efficiency and reducing costs.
Implementation Method 1
The fiber modifying agent functions as either one or both (1) a plasticizer that reduces the polymer extrudate melt viscosity and allows the formation of fine fibers during processing
Implementation Method 2
a surface modifying agent that promotes the instantaneous and sustained wettability of individual polymer fibers and a porous fiber sheet formed from them
Implementation Method 3
the porous separator prevents the electrodes from coming into physical contact and provides space for an electrolyte to reside. Such separators are formed of materials that are resistant to the sulfuric acid electrolyte, readily wettable in sulfuric acid, and sufficiently porous to permit the electrolyte to reside in the pores of the separator material, thereby permitting ionic current flow
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A polymer fiber sheet exhibits high porosity and good tensile properties in both "wet" and "dry" states. A fiber modifying agent is incorporated into a polymer extrusion and fiber formation process to produce a highly porous polymer fiber sheet that is instantaneously wettable by an aqueous medium. The fiber modifying agent functions as either one or both (1) a plasticizer that reduces the polymer extrudate melt viscosity and allows the formation of fine fibers during processing and (2) a surface modifying agent that promotes the instantaneous and sustainable wettability of individual polymer fibers and a porous fiber sheet formed from them. The polymer fiber sheet maintains its wettability even after repeated washing and drying cycles. The resultant fiber sheet can be densified and embossed to provide a desired thickness and porosity, while at the same time longitudinal ribs with desired pattern can also be formed on the fiber sheet.