Battery Cell Pressure Relief Weak Region for Thermal Runaway Venting
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Solution Overview
Problem
Existing battery technologies face challenges in ensuring the safety of battery cells, particularly in preventing thermal runaway, which can lead to fires and explosions, due to the difficulty in balancing the strength and reliability of pressure relief mechanisms.
Innovation Solution
A pressure relief apparatus with a weak region designed to break during thermal runaway, featuring a specific hardness-to-thickness ratio (5 HBW/mm ≤ A/a ≤ 10000 HBW/mm) and a non-weak region with a different thickness and hardness, ensuring timely pressure relief while maintaining sufficient strength for normal use, thereby enhancing the safety and service life of battery cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the pressure relief apparatus is made with high strength to prevent premature breakage, then the service life is prolonged, but the pressure relief capability during thermal runaway is reduced
Solution Approach 1:
The pressure relief apparatus employs different material properties in different regions: the weak region has lower hardness (8-200 HBW) and smaller thickness (0.02-1.6 mm) to enable timely breakage during thermal runaway, while the non-weak region has higher hardness and larger thickness to maintain structural strength during normal use. This local differentiation resolves the contradiction between strength and pressure relief capability.
Solution Approach 2:
The pressure relief apparatus is divided into distinct functional segments: a weak region configured to break during thermal runaway events and a non-weak region that maintains structural integrity during normal operation. This segmentation allows each region to be optimized for its specific function, resolving the contradiction between premature breakage prevention and pressure relief capability.
2Speed
If the weak region thickness is reduced to enable timely pressure relief, then the pressure relief speed is improved, but the service life is reduced due to premature breakage
Solution Approach 1:
The apparatus uses localized thinning to create a weak region with smaller thickness (0.02-1.6 mm) that enables rapid pressure relief during thermal runaway, while the overall structure maintains sufficient thickness in non-weak regions to prevent premature breakage and extend service life during normal operation.
Solution Approach 2:
The hardness parameter of the weak region is specifically controlled (8-200 HBW) to be lower than the non-weak region, creating a controlled weakness that enables timely pressure relief without compromising the overall structural integrity and service life of the battery cell.
3Strength
If the hardness of the weak region is increased to prevent premature breakage, then the service life is prolonged, but the pressure relief capability is reduced
Solution Approach 1:
The weak region is designed with specific hardness properties (8-200 HBW) that are lower than the non-weak region, creating a localized area that will break first during thermal runaway while maintaining sufficient overall strength for normal operation.
Solution Approach 2:
The pressure relief apparatus functions as a composite structure with regions of different material properties - the weak region has lower hardness to enable pressure relief while the non-weak region has higher hardness to maintain structural integrity, resolving the contradiction between strength and pressure relief timeliness.
Data Source
AI summary
This application provides a pressure relief apparatus, a housing, a battery cell, a battery, and an electrical device. The pressure relief apparatus is applicable to the battery cell. A weak region is locally formed on the pressure relief apparatus and configured to break when the battery cell relieves pressure. The weak region has a thickness of a and a hardness of A, satisfying: 5 HBW/mm≤A/a≤10000 HBW/mm. A ratio of the hardness to the thickness of the weak region is set within a reasonable range, so that the weak region has sufficient strength in the normal use process of the battery cell, and the pressure relief apparatus is not easily breakable at the weak region, and the service life of the battery cell is prolonged; and the pressure relief apparatus can timely relieve pressure at the time of thermal runaway of the battery cell.