Roughened Battery Case Sealing Against Electrolyte Leakage
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Solution Overview
Problem
Sealed batteries face liquid leakage issues due to degradation of insulating members, which can lead to electrolyte leakage, especially under high temperature conditions or due to aging, as the insulating members deform and create gaps between the terminal member, insulating member, and battery case.
Innovation Solution
The sealed battery design incorporates a rough surface area on at least one surface of the battery case and/or terminal member with an arithmetic average roughness of 1 μm or more, increasing friction resistance to prevent deformation of the insulating member and thus inhibit electrolyte leakage. This design can be applied to both the outside and inside terminal structures, including the use of gaskets and plate-shaped members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an insulating member made of resin is arranged between the terminal member and the battery case to inhibit conduction and close gaps, then sealing property is improved, but the insulating member degrades under high temperature or aging conditions causing deformation and liquid leakage
Solution Approach 1:
The patent changes the surface parameter of the metal members by creating a rough surface area with arithmetic average roughness of 1 μm or more. This surface modification increases friction resistance between the metal member and insulating member, preventing insulating member deformation even under high temperature or aging conditions, thereby maintaining sealing property without compromising insulating member stability.
2Reliability
If the insulating member is pressurized together with the terminal member to close gaps, then sealing property is improved, but the insulating member deforms under pressure when degraded, causing gaps and electrolyte leakage
Solution Approach 1:
The patent modifies the surface parameter of the metal member by creating a rough surface area with arithmetic average roughness of 1 μm or more. This surface roughness increases friction resistance, which counteracts the deforming pressure on the insulating member. The increased friction prevents the insulating member from deforming under pressure, maintaining both sealing property and structural strength.
3Ease of manufacture
If a smooth surface is used between the battery case and terminal member, then ease of manufacture is improved, but friction resistance is insufficient allowing insulating member deformation and leakage
Solution Approach 1:
The patent changes the surface parameter by creating a rough surface area with arithmetic average roughness of 1 μm or more on the metal member. This can be achieved through conventional surface treatment methods such as sandblasting, shot peening, or chemical etching. The rough surface increases friction resistance to prevent insulating member deformation, thereby improving sealing property while maintaining ease of manufacture through standard surface treatment processes.
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 rough surface area effectively regulates the deformation of insulating members, preventing gaps and thereby suppressing electrolyte leakage, even under degradated conditions, and offers a more refined sealing structure compared to conventional techniques.
Implementation Method 1
a surface of a battery case and/or an opposed surface of a terminal member includes a rough surface area on at least a part of a portion contacting with an insulating member, and an arithmetic average roughness Sa of a rough surface area is equal to or more than 1 μm
Data Source
AI summary
The herein-disclosed sealed battery includes a battery case, a terminal member (negative electrode external terminal) including an opposed surface opposed to the battery case, and an insulating member (negative side gasket) disposed between the sealing plate and the negative electrode external terminal. Then, the surface of the battery case and/or an opposed surface of the negative electrode external terminal includes a 1st rough surface area on at least a part of a portion contacting with the negative side gasket, and an arithmetic average roughness Sa of the 1st rough surface area is equal to or more than 1 μm. By doing this, it is possible to suppress a liquid leakage of an electrolyte caused by degradation of the negative side gasket.