Lead-Acid Battery Separator Pore Optimization
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Solution Overview
Problem
Lead-acid batteries face challenges in reducing separator resistance while maintaining high-temperature overcharge life, as the presence of oil in the separator increases resistance but its removal shortens battery life, and adjusting the pH of inorganic powders does not sufficiently reduce resistance.
Innovation Solution
A lead-acid battery design with a separator containing polyolefin and oil, optimized by adjusting pore volume and surface area within specific ranges to enhance diffusivity and hold oil, reducing resistance and oxidative deterioration, thereby improving high-temperature overcharge life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If oil is contained in the separator as a pore-forming additive, then the high-temperature overcharge life is improved, but the resistance of the separator increases
Solution Approach 1:
The patent changes the physical parameters of the separator by controlling pore volume (0.7-1.2 mL/g) and pore surface area (3.0-8.0 m²/g) to optimize the balance between oil retention and resistance reduction. This parameter optimization allows the separator to maintain both long service life and low resistance
Solution Approach 2:
The patent uses composite materials by combining polyolefin resin with specific amounts of oil (5-20 parts by mass per 100 parts resin) and inorganic powders with pH 6.5 or less. This composite structure enables the separator to simultaneously achieve low resistance and high-temperature durability
2Reliability
If oil is removed from the separator, then the resistance of the separator decreases, but the high-temperature overcharge life is shortened
Solution Approach 1:
The patent optimizes the pore volume parameter to 0.7-1.2 mL/g and pore surface area to 3.0-8.0 m²/g, which creates an optimal pore structure that retains sufficient oil for high-temperature life while maintaining low resistance through controlled porosity
Solution Approach 2:
The patent utilizes porous materials by creating a controlled pore structure in the separator with specific pore volume and surface area. The porous structure allows oil to be held within the pores, providing both low resistance pathways and protection against oxidative deterioration
3Ease of operation
If the pH of inorganic powder is set to 6.5 or less to improve wettability, then the wettability with electrolyte solution is improved to some extent, but the resistance of the separator is not sufficiently reduced
Solution Approach 1:
The patent changes multiple parameters simultaneously: inorganic powder pH (≤6.5), pore volume (0.7-1.2 mL/g), and pore surface area (3.0-8.0 m²/g). This multi-parameter optimization achieves sufficient resistance reduction that cannot be achieved by pH adjustment alone
Solution Approach 2:
The patent creates a composite material system combining low-pH inorganic powder (pH ≤6.5) with controlled pore structure and oil content. This composite approach enhances wettability through the inorganic powder while the pore structure and oil content work together to reduce overall separator resistance
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 optimized separator structure achieves low resistance and extended high-temperature overcharge life, enhancing the battery's startability and durability, particularly suitable for applications requiring large currents like vehicle starting.
Implementation Method 1
the separator has a pore volume (A) of 0.70 mL/g or more and a pore surface area (B) of 3.0 m2/g or more, and a product (C) of the pore volume (A) and the pore surface area (B) is 92 or more
Implementation Method 2
the oil is held in the separator, it is possible to provide a lead-acid battery having both a low separator resistance and an excellent high-temperature overcharge life
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A lead-acid battery includes: a positive electrode plate; a negative electrode plate; and a separator interposed between the positive electrode plate and the negative electrode plate. The separator contains a polyolefin and an oil. The separator has a pore volume A of 0.80 cm3/g or more and 1.55 cm3/g or less and a pore surface area B of 65 cm2/g or more and 116 cm2/g or less. A product C of the pore volume A and the pore surface area B is 92 or more and 178 or less.