Rechargeable Battery Case Bottom Elongation for Crack Prevention
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Solution Overview
Problem
Rechargeable batteries can experience internal short-circuits and potential explosions when subjected to longitudinal compression due to cracks in the case, which are caused by bending, leading to safety concerns.
Innovation Solution
The battery case is designed with a bottom that includes a first and second elongation portion, where the second elongation portion has a higher elongation ratio, allowing for controlled bending without crack formation, and a heat treatment device is used to maintain these elongation ratios, preventing internal short-circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the case is made rigid to maintain structural strength, then the case can withstand compression forces, but cracks form during bending under longitudinal compression causing internal short-circuits
Solution Approach 1:
The bottom of the case is divided into different regions with distinct mechanical properties: a first region with higher elasticity modulus and a second region with lower elasticity modulus. This local differentiation allows the case to maintain overall structural strength while enabling controlled bending in the softer second region, preventing crack formation during longitudinal compression.
Solution Approach 2:
The case bottom employs a composite structure combining materials or regions with different elasticity moduli. The first region uses a stiffer material for strength, while the second region uses a more flexible material for crack resistance, creating a composite structure that simultaneously achieves both structural integrity and bending flexibility.
2Reliability
If the case is made flexible to allow bending without cracks, then crack resistance improves, but structural strength decreases compromising battery safety
Solution Approach 1:
The bottom of the case is divided into different regions with distinct mechanical properties: a first region with higher elasticity modulus and a second region with lower elasticity modulus. This local differentiation allows the case to maintain overall structural strength while enabling controlled bending in the softer second region, preventing crack formation during longitudinal compression.
Solution Approach 2:
The case bottom employs a composite structure combining materials or regions with different elasticity moduli. The first region uses a stiffer material for strength, while the second region uses a more flexible material for crack resistance, creating a composite structure that simultaneously achieves both structural integrity and bending flexibility.
3Ease of manufacture
If uniform material properties are used throughout the case, then manufacturing is simplified, but the case cannot accommodate both bending flexibility and structural strength requirements
Solution Approach 1:
The bottom of the case is divided into different regions with distinct mechanical properties: a first region with higher elasticity modulus and a second region with lower elasticity modulus. This local differentiation allows the case to maintain overall structural strength while enabling controlled bending in the softer second region, preventing crack formation during longitudinal compression.
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 design effectively prevents crack formation and internal short-circuits during longitudinal compression, ensuring the battery's safety and reliability by allowing the case to bend without cracking, thus maintaining the battery's functionality.
Implementation Method 1
a heating portion provided between the cooling portions in the first length direction to apply a second elongation ratio that is higher than the first elongation ratio by partially heating a second portion set between the first portions
Implementation Method 2
a cooling portion maintaining a first elongation ratio by partially cooling first portions formed at both sides of a first length direction of the bottom
Data Source
AI summary
An embodiment of the present invention provides a rechargeable battery that prevents generation of a crack under the longitudinal compression condition by increasing an elongation ratio to a part of the bottom of the case to prevent an internal short-circuit. A rechargeable battery according to an exemplary embodiment of the present invention includes: a case receiving an electrode assembly; a cap plate covering an opening of the case; and an electrode terminal provided in the cap plate and electrically connected to the electrode assembly, the case includes side walls connected with each other and forming the opening in one side and a bottom connecting neighboring side walls at the opposite side of the opening for sealing, and the bottom a first elongation portion having a first elongation ratio and a second elongation portion having a second elongation ratio that is higher than the first elongation ratio.