Cross-linked Microporous Polysulfone Separator for Thermal Safety
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Solution Overview
Problem
Conventional battery electrode separators fail to maintain integrity and safety at high temperatures, leading to overheating and fires in lithium ion batteries due to dissolution, melting, or structural weakness in electrolyte solvents.
Innovation Solution
A cross-linked microporous polysulfone battery electrode separator with a porosity greater than 30% and an air flow exceeding 1 cm/min·torr, composed of between 10 wt% and 90 wt% polysulfone or sulfone copolymer and 10 wt% to 90 wt% aerogel, which prevents dissolution in battery electrolytes at temperatures below 75°C and provides structural durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polyolefin separators are used, then manufacturing cost is low and ease of manufacture is good, but they dissolve or develop pinholes in electrolyte solvents at temperatures above 60°C
Solution Approach 1:
The patent uses composite materials by combining polysulfone polymer with cross-linking agents to create a separator that maintains structural integrity at high temperatures while resisting dissolution in electrolyte solvents. The cross-linked polysulfone matrix provides both thermal stability and chemical resistance that conventional polyolefins lack.
2Reliability
If fluoroplastic separators are used, then high temperature durability is improved, but manufacturing cost increases significantly
Solution Approach 1:
The patent changes the chemical parameters of the separator material by using cross-linked polysulfone instead of fluoroplastics. This parameter change achieves comparable high-temperature durability and chemical resistance while significantly reducing manufacturing cost, as polysulfone is a more economically viable material than fluoroplastic alternatives.
3Productivity
If separator thickness is reduced to maximize ion flow, then productivity increases, but structural strength and resistance to dendrites decrease
Solution Approach 1:
The patent employs porous materials by creating a microporous structure in the cross-linked polysulfone separator. This porous architecture allows high ion flow rates comparable to thinner separators while the cross-linked polymer matrix provides enhanced structural strength to resist dendrite penetration, effectively decoupling the trade-off between thickness and strength.
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 significantly enhances safety against overheating and fires by reducing the effects of dendrites and particulate contaminants, allowing continued battery usage with electronic or thermal controls detecting potential issues, and offers a lower cost alternative to fluoropolymer separators.
Implementation Method 1
cross-linked, microporous polysulfone battery electrode separator
Implementation Method 2
The membranes are necessarily thin and microporous to maximize the flow of ions during charging and discharging of the batteries
Data Source
AI summary
A cross-linked microporous polysulfone or polysulfone copolymer battery electrode separator membrane are described. Such membranes, which would otherwise be soluble above a particular, generally high temperature in selected battery electrolyte systems, once at least in part cross-linked, swell in the electrolyte at the particular higher temperature instead of dissolving. When the membrane separators are restrained between solid electrodes in a battery, the separator cannot increase in bulk volume, and the swelling occurs within the pores with the pore volume decreasing from its original bulk volume. The drop in pore volume causes the battery current density to drop, thereby reducing the heat generation within the hot area of the battery. This process provides a measure of safety against overheating and fires, and the battery is capable of continued usage if the overheating is localized.