Battery Cell Shell Venting Structure for Timely Pressure Relief
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Solution Overview
Problem
The service life of battery cells is limited by the reliability of pressure relief mechanisms, which are prone to failure due to cracks at weld positions and delayed pressure relief during thermal runaway, compromising safety and performance.
Innovation Solution
A shell component with a non-fragile and fragile region formed in one piece, where the fragile region has a higher hardness than the non-fragile region, allowing for timely pressure relief during thermal runaway while maintaining strength during normal use, by controlling the hardness and grain size ratios and thickness to ensure timely and effective pressure release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fragile region has high hardness to maintain strength during normal use, then the service life of the battery cell is improved, but the fragile region may not break in time during thermal runaway, compromising safety
Solution Approach 1:
The shell component is designed with regions of different hardness: a fragile region with higher hardness (H1) for strength during normal use, and a non-fragile region with lower hardness (H2) for timely pressure relief during thermal runaway. The hardness ratio H1/H2 is controlled between 1.1 and 5 to balance these competing requirements.
Solution Approach 2:
The patent controls specific parameter ranges: hardness ratio H1/H2 between 1.1 and 5, grain size ratio S1/S2 between 0.05 and 0.9, and thickness ratio A/B between 0.05 and 0.95. These parameter optimizations ensure the fragile region maintains sufficient strength for normal operation while being capable of breaking for pressure relief during thermal runaway.
2Object-affected harmful factors
If the fragile region has low hardness to enable timely pressure relief during thermal runaway, then safety is improved, but the fragile region may break during normal use, reducing service life
Solution Approach 1:
The shell component is designed with regions of different hardness: a fragile region with higher hardness (H1) for strength during normal use, and a non-fragile region with lower hardness (H2) for timely pressure relief during thermal runaway. The hardness ratio H1/H2 is controlled between 1.1 and 5 to balance these competing requirements.
Solution Approach 2:
The shell component comprises two regions with different material properties: the fragile region with higher hardness and smaller grain size for strength, and the non-fragile region with lower hardness for ductility and pressure relief. This composite structure optimizes both service life and safety performance.
3Reliability
If the fragile region has small grain size to improve mechanical properties and toughness, then the service life is improved, but the molding difficulty increases and the fragile region becomes harder to break
Solution Approach 1:
The patent optimizes the grain size ratio S1/S2 between 0.05 and 0.9, ensuring the fragile region has sufficiently small grain size for improved toughness and fatigue resistance while maintaining manufacturability. This parameter control balances performance requirements with manufacturing feasibility.
4Strength
If the fragile region has large thickness to maintain structural integrity, then strength during normal use is improved, but the pressure relief is delayed, compromising safety
Solution Approach 1:
The shell component is designed with regions of different hardness: a fragile region with higher hardness (H1) for strength during normal use, and a non-fragile region with lower hardness (H2) for timely pressure relief during thermal runaway. The hardness ratio H1/H2 is controlled between 1.1 and 5 to balance these competing requirements.
Solution Approach 2:
The shell component comprises two regions with different material properties: the fragile region with higher hardness and smaller grain size for strength, and the non-fragile region with lower hardness for ductility and pressure relief. This composite structure optimizes both service life and safety performance.
Data Source
AI summary
This application provides a shell component, a battery cell, a battery, and an electrical device, and relates to the technical field of batteries. The shell component includes a non-fragile region and a fragile region formed in one piece. A groove portion is disposed on the shell component. The non-fragile region is formed around the groove portion. The fragile region is formed at a bottom of the groove portion. The fragile region is configured to be broken when the battery cell is relieved of an internal pressure. A hardness of the fragile region is H1, and a hardness of the non-fragile region is H2, satisfying: H1>H2. The hardness of the fragile region is greater than the hardness of the non-fragile region.