Battery Cell Pressure Relief Notch Placement Against Housing Deformation
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Solution Overview
Problem
The pressure relief parts in battery cells are prone to rupture due to deformation of the housing, leading to reduced reliability and potential liquid leakage during expansion of the electrode assembly.
Innovation Solution
The battery cell design includes a pressure relief part with a score groove recessed in a direction away from the outer surface of the wall part, maintaining a specific distance to reduce the impact of deformation and tension, thereby minimizing the risk of rupture and liquid leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pressure relief part is disposed on the housing, then the battery cell can release pressure when subjected to predetermined conditions, but the pressure relief part is prone to rupture due to housing deformation during electrode assembly expansion
Solution Approach 1:
The housing is divided into multiple wall parts (first wall part, second wall part, third wall part) with distinct functions. The pressure relief part is specifically disposed on the first wall part, separating it from the second and third wall parts that directly accommodate the electrode assembly. This segmentation isolates the pressure relief mechanism from the deformation-prone regions, reducing rupture risk while maintaining pressure relief functionality.
Solution Approach 2:
The score groove is pre-formed on the pressure relief part at a location spaced apart from the second wall part. This preliminary structural feature creates a controlled rupture path that is predetermined to occur away from the deformation-prone second wall part, ensuring that when pressure relief is needed, the rupture occurs in a safe location that minimizes the risk of additional damage from housing deformation.
2Speed
If the score groove is positioned close to the second wall part, then the pressure relief part can rupture timely under pressure, but the weakened zone is directly ruptured by tension from second wall part deformation
Solution Approach 1:
The pressure relief part has non-uniform structural properties due to the score groove placement. The score groove creates a localized weakened zone specifically positioned away from the second wall part, while other regions of the pressure relief part maintain full structural integrity. This local quality differentiation ensures that rupture occurs at the predetermined score groove location (enabling timely pressure relief) while the rest of the structure remains strong enough to resist deformation-induced tension from the second wall part.
3Strength
If the housing wall thickness is increased to reduce deformation, then the structural strength is improved, but the volumetric energy density of the battery cell decreases
Solution Approach 1:
The housing wall thickness is segmented into different regions with different thickness values. The first wall part (containing the pressure relief part) has a first thickness, while the second and third wall parts have a second thickness that is smaller than the first thickness. This segmentation allows the first wall part to have sufficient strength to protect the pressure relief mechanism, while the thinner second and third wall parts maximize the internal volume available for electrode assembly, thereby maintaining high volumetric energy density.
Data Source
AI summary
A battery cell, a battery, and an electric device. The battery cell comprises: an electrode assembly, and a housing, the housing comprising a first wall portion and two second wall portions, wherein the first wall portion is provided with a pressure relief portion, and the pressure relief portion is provided with a notch groove recessed in a second direction; the pressure relief portion is configured to crack along at least part of the notch groove when the battery cell is subjected to pressure relief; and in a first direction, the notch groove is spaced apart from the outer surface of either of the two second wall portions.