Battery Cell Partition Thermal Resistance for Runaway Isolation
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Solution Overview
Problem
Conventional technologies fail to quantitatively address thermal resistance values necessary to prevent positive-feedback damage between battery cells, particularly in high-energy density secondary batteries, leading to potential thermal runaway and damage spread.
Innovation Solution
A partition member with specific thermal resistance values (θ1≥5.0×10−3 m2·K/W and θ2≤4.0×10−3 m2·K/W) is used to separate battery cells, controlling heat transfer based on surface temperature thresholds to prevent heat propagation between cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If energy density of secondary batteries is increased to extend cruising range, then productivity and energy efficiency are improved, but safety deteriorates due to higher risk of thermal runaway and damage spread between cells
Solution Approach 1:
The battery pack is segmented into multiple independent battery modules, each surrounded by insulating members. This segmentation prevents thermal runaway from spreading between modules, allowing higher energy density in each module while maintaining overall safety. The insulating members create thermal barriers that isolate individual cells, enabling the system to achieve extended cruising range without compromising safety.
Solution Approach 2:
Insulating members are introduced as intermediary elements between battery cells and modules. These intermediaries serve as thermal barriers that block heat transfer pathways, preventing the propagation of thermal runaway. The insulating members act as mediators that allow the battery system to operate at higher energy densities while maintaining safety through controlled thermal isolation.
2Reliability
If cooling units are added to suppress heat transfer between damaged and undamaged cells, then safety is improved, but device complexity increases
Solution Approach 1:
The cooling function is extracted from the traditional active cooling system and integrated into the structural insulating members themselves. The insulating members are positioned to naturally isolate thermal pathways between battery modules, eliminating the need for separate active cooling units. This extraction approach maintains safety by preventing heat transfer while significantly reducing device complexity.
Solution Approach 2:
The insulating members provide self-service thermal management by inherently blocking heat transfer pathways through their material properties and positioning. Rather than requiring external cooling systems, the structure itself performs the safety function through passive thermal isolation. The insulating members automatically prevent thermal runaway propagation without needing external control systems or additional components.
3Reliability
If partition members with high thermal resistance are used to prevent heat propagation, then safety is improved, but heat dissipation during normal operation deteriorates
Solution Approach 1:
Thermal resistance properties are locally optimized in different regions of the battery pack. Insulating members with high thermal resistance are strategically positioned at critical interfaces between battery modules where thermal runaway propagation risk is highest. In regions where heat dissipation is prioritized, the insulating members are positioned or designed to allow thermal pathways. This local quality approach ensures safety at critical points while maintaining efficient heat dissipation elsewhere.
Solution Approach 2:
The insulating members are designed to allow rapid heat dissipation during normal operation by providing thermal pathways, but quickly block heat transfer when thermal runaway conditions are detected. The system skips from a heat-conductive state during normal operation to a heat-blocking state during abnormal conditions, achieving both efficient heat dissipation and safety when needed.
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 partition member effectively reduces heat transfer between abnormal and normal cells, preventing thermal runaway and maintaining cell safety by managing thermal resistance according to temperature conditions.
Implementation Method 1
when the average temperature of one of the two surfaces exceeds 180° C., a thermal resistance per unit area (θ1) in the thickness direction satisfies Expression (1); and when the average temperatures of both of the two surfaces do not exceed 80° C., a thermal resistance per unit area (θ2) in the thickness direction satisfies Expression (2)
Data Source
AI summary
A partition member has two surfaces in a thickness direction, and separates single cells that make up an assembled battery. When the average temperature of one of the two surfaces exceeds 180° C., a thermal resistance per unit area (θ1) in the thickness direction satisfies Expression 1 below, and when the average temperatures of both of the two surfaces do not exceed 80° C., a thermal resistance per unit area (θ2) in the thickness direction satisfies Expression 2 below.θ1≥5.0×10−3 (m2·K/W) (Expression 1), andθ2≤4.0×10−3 (m2·K/W) (Expression 2).