Radiation-Treated Microporous Battery Separators for Thermal Shutdown
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing microporous polyolefin battery separator membranes in lithium batteries suffer from narrow thermal shutdown windows, high thermal shrinkage, and limited oxidation resistance, posing safety risks due to potential thermal runaway events.
Innovation Solution
Ionizing radiation treatment, specifically electron beam radiation, is applied to modify the properties of polyethylene-based microporous membranes, enhancing thermal shutdown onset temperature, extending the thermal shutdown window, and reducing thermal shrinkage, while maintaining mechanical integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ionizing radiation treatment is applied to polyethylene-based microporous membranes, then oxidation resistance is improved, but mechanical integrity may be compromised
Solution Approach 1:
The ionizing radiation treatment modifies the chemical parameters of the polyethylene membrane by creating cross-linked structures and altering molecular weight distribution. This enhances oxidation resistance through improved chemical stability while the controlled radiation dosage maintains adequate mechanical integrity.
2Reliability
If the thermal shutdown window is extended to higher temperatures, then battery safety is improved, but the membrane may lose physical integrity at elevated temperatures
Solution Approach 1:
The radiation treatment fundamentally changes the thermal stability parameters of the polyethylene membrane by inducing cross-linking and modifying crystalline structure. This enables the membrane to maintain physical integrity at temperatures where untreated polyethylene would decompose, extending the safe operating temperature range.
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 treated membranes exhibit a lower onset temperature of thermal shutdown, wider thermal shutdown window, improved oxidation resistance, and reduced thermal shrinkage, thereby enhancing safety and performance in lithium batteries by preventing anode-cathode contact and potential short circuits.
Implementation Method 1
Ionizing radiation may include high speed, energetic, subatomic particles, ions or small atoms, or the like. Without wishing to be bound by theory, ionizing radiation may remove electrons from atoms or molecules when it passes through or collides with a material.
Implementation Method 2
The ionized atoms or molecules can undergo radiolysis and form free radicals to trigger further chemical reactions.
Implementation Method 3
One form of ionizing radiation is an electron beam or e-beam radiation. E-beam radiation can be high (5 to 10 MeV), medium (500 keV to 5 MeV) or low (80 to 500 keV) in energy level.
Implementation Method 4
e-beam radiation of polyolefinic materials may break C—C (4.25 eV) and C—H (3.60 eV) bonds forming free radicals which may trigger a competing process of chain scission vs. cross-linking.
Implementation Method 5
e-beam radiation of polyolefinic materials may break C—C (4.25 eV) and C—H (3.60 eV) bonds forming free radicals which may trigger a competing process of chain scission vs. cross-linking.
Data Source
AI summary
In accordance with at least selected embodiments, novel or improved separator membranes, separators, batteries including such separators, methods of making such membranes and/or separators, and/or methods of using such membranes and/or separators are disclosed or provided. In accordance with at least certain embodiments, an ionized radiation treated microporous polyolefin, polyethylene (PE), copolymer, and/or polymer blend (e.g., a copolymer or blend comprising PE and another polymer, such as polypropylene (PP)) battery separator for a secondary or rechargeable lithium battery and/or a method of making an ionized radiation treated microporous battery separator is disclosed. The ionized radiation treatment may provide a microporous membrane or battery separator having a lower onset temperature of thermal shutdown, an extended thermal shutdown window, physical, dimensional, and/or mechanical integrity maintained at higher temperatures, improved battery safety performance in a rechargeable lithium battery, a treated polyethylene separator membrane with the high temperature performance of a polypropylene membrane or separator membrane, or polypropylene-based trilayer product (by way of example only, a trilayer membrane made of two polypropylene layers with a polyethylene layer in between), reduced thermal shrinkage resulting in both improved thermal stability and high temperature physical integrity, which maintains the separation of cathode and anode in a battery system and avoids thermal runaway in a rechargeable or secondary lithium battery, and/or combinations thereof.