Stainless Steel Lid Member for Electrochemical Cell Sealing
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Solution Overview
Problem
Conventional electrochemical cells, particularly in chip-type form, face issues with nickel-based jointing materials melting during charging and discharging, leading to increased leakage current and decreased charging efficiency over time, due to thermal expansion and potential exposure of base metals.
Innovation Solution
The use of a stainless steel lid member with a thickness of 30 µm or less, coated with a dense oxide layer and a metal layer, welded via seam or laser beam welding, to prevent nickel flow and enhance corrosion resistance, thereby reducing leakage current and maintaining charging efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If nickel-based jointing material is used to connect the sealing plate and base member, then assembly workability is improved, but the material melts during charging and discharging causing increased leakage current and decreased charging efficiency
Solution Approach 1:
The patent changes the material parameter from nickel-based alloy to stainless steel for the lid member, which has a higher melting point and better thermal stability. This material substitution resolves the contradiction by maintaining ease of assembly while preventing melting during charging/discharging cycles, thereby maintaining charging efficiency.
Solution Approach 2:
The patent employs a composite structure where the lid member is made of stainless steel with specific thickness (30 µm or less) and is connected via welding rather than nickel-based jointing material. This composite approach combines the benefits of stainless steel's high melting point with the thin profile needed for chip-type batteries, resolving the reliability issue while maintaining manufacturability.
2Length of moving object
If the lid member is made thinner to reduce cell thickness, then space saving is improved, but manufacturing precision becomes more difficult to control
Solution Approach 1:
The patent specifies a precise thickness parameter for the lid member (30 µm or less) and combines it with seam welding technology that can accurately join thin materials. This parameter optimization resolves the contradiction by enabling thin-profile batteries while maintaining manufacturing precision through controlled welding parameters and material specifications.
3Manufacturing precision
If seam welding is used to connect the lid member and base member, then manufacturing precision is improved, but the base member peripheral wall portion may be damaged due to heat
Solution Approach 1:
The patent optimizes the lid member thickness to 30 µm or less, which reduces the heat input required for welding. This parameter change allows seam welding to be performed with lower heat intensity, achieving precise welding while minimizing thermal damage to the ceramic base member's peripheral wall portion.
Solution Approach 2:
The use of a thin lid member (30 µm or less) acts as a flexible, thin-film component that requires minimal heat for welding. This thin-film approach enables precise seam welding while protecting the base member from excessive heat, as the thin lid member can be joined quickly with low thermal input.
4Reliability
If stainless steel is used for the lid member instead of nickel-based alloy, then corrosion resistance is improved, but assembly workability may be reduced
Solution Approach 1:
The patent replaces the mechanical connection method (nickel-based jointing material) with a thermal connection method (seam welding). This substitution resolves the contradiction by enabling the use of stainless steel, which has superior corrosion resistance, while maintaining assembly feasibility through welding technology that is well-suited for stainless steel materials.
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
This configuration stabilizes the electrochemical cell's quality over time by preventing nickel flow and reducing leakage current, improving cycle characteristics and assembly workability while lowering production costs.
Implementation Method 1
the lid member is made of stainless steel, the lid member is welded on an upper surface of the peripheral wall portion of the base member via the jointing material by seam welding in which welded parts are overlapped continuously on a boundary surface between the lid member and the jointing material, characterized in that the lid member has a thickness less than or equal to 30 μm, and a wall thickness T (μm) of the peripheral wall portion and a welded diameter φ (μm) of the welded parts satisfy the following formula
Implementation Method 2
the lid member is welded on an upper surface of the peripheral wall portion of the base member via the jointing material by seam welding in which welded parts are overlapped continuously on a boundary surface between the lid member and the jointing material
Data Source
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AI summary
The electrochemical cell (1) of the present invention is provided with a hermetic container (2) having a base member (10), a jointing material (12) fixed to the base member, and a lid member (11) welded on the base member via the jointing material, and in which a housing space (S) sealed between the base member and the lid member is defined, and an electrochemical element (3) which is housed inside the housing space and which is available to effect charging and discharging, wherein the lid member is made of stainless steel.