Positive Electrode Layer Structure Balancing Thermal Runaway and Capacity
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Solution Overview
Problem
Rechargeable lithium batteries face challenges in achieving improved safety, particularly in preventing battery explosions and fires when pierced by sharp objects or subjected to physical impact.
Innovation Solution
A positive electrode for rechargeable lithium batteries is designed with a heat suppression layer between the current collector and the positive active material layer, maintaining a thickness ratio of about 1:5 to 1:20, which enhances safety by reducing heat generation and preventing thermal runaway.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a heat suppression layer is added between the current collector and the positive active material layer, then safety is improved by preventing thermal runaway, but device complexity increases due to additional layer structure
Solution Approach 1:
The positive electrode is segmented into multiple functional layers: the current collector, the heat suppression layer (containing heat-resistant filler particles), and the positive active material layer. This segmentation allows each layer to perform its specific function independently, with the heat suppression layer acting as a thermal barrier to prevent thermal runaway while maintaining overall electrode functionality.
Solution Approach 2:
The heat suppression layer serves as an intermediary layer between the current collector and the positive active material layer. This intermediate layer contains heat-resistant filler particles that absorb and dissipate heat, preventing direct thermal transfer from the active material to the current collector, thereby suppressing thermal runaway without requiring fundamental changes to the electrode architecture.
2Reliability
If the heat suppression layer thickness is increased to improve safety, then thermal runaway prevention is enhanced, but capacity is reduced due to lower active material content
Solution Approach 1:
The thickness of the heat suppression layer is optimized to a specific range (1-10 μm) to achieve the desired balance between safety and capacity. Within this parameter range, the heat suppression layer provides sufficient thermal protection while minimizing the displacement of active material, thereby maintaining acceptable battery capacity. The heat-resistant filler particle concentration is also adjusted (1-10 parts by weight per 100 parts by weight of binder) to optimize both thermal and electrical properties.
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 implementation of the positive electrode with a heat suppression layer effectively improves the safety of rechargeable lithium batteries by preventing ignition and maintaining capacity within the specified thickness ratio.
Implementation Method 1
a heat suppression layer between the current collector and the positive active material layer, wherein a thickness ratio of the heat suppression layer and the positive active material layer is about 1:5 to about 1:20
Data Source
AI summary
A positive electrode and a rechargeable lithium battery including the same, and the positive electrode includes a current collector, a positive electrode including a positive active material, and a heat suppression layer between the current collector and the positive active material layer, wherein a thickness ratio of the heat suppression layer and the positive active material layer is about 1:5 to about 1:20.