Battery Container Steel Sheet With Controlled Fe-Ni Diffusion
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Solution Overview
Problem
Conventional surface-treated steel sheets for battery containers face issues with corrosion resistance when the thickness of the can wall is reduced, leading to increased iron dissolution and decreased corrosion resistance, especially when heat treatment conditions result in excessive iron-nickel diffusion, causing local exposure and increased gas generation within the battery.
Innovation Solution
A surface-treated steel sheet with a specific iron-nickel diffusion layer and nickel layer configuration, where the thickness of the iron-nickel diffusion layer is between 0.04 to 0.31 μm and the total nickel content is 10.8 to 26.7 g/m², along with a nickel layer thickness of 1.0 μm or more, is used, enhancing corrosion resistance while maintaining a thin can wall for improved volume percentage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the thickness of the can wall is reduced to improve volume percentage, then the volume efficiency is improved, but the corrosion resistance is decreased due to increased iron dissolution
Solution Approach 1:
The invention changes the parameters of the surface treatment layer, specifically controlling the thickness of the iron-nickel diffusion layer (0.03 to 0.50 μm) and the total nickel content (10.8 to 26.7 g/m²), to maintain corrosion resistance even when the can wall thickness is reduced. This parameter optimization allows thin-walled containers to achieve both high volume percentage and adequate corrosion resistance.
2Stability of the object's composition
If conventional heat treatment conditions are used to form the iron-nickel diffusion layer, then the diffusion layer is formed, but excessive inter-diffusion occurs leading to increased iron dissolution
Solution Approach 1:
The invention optimizes the heat treatment parameters by controlling the diffusion layer thickness to 0.03 to 0.50 μm and the total nickel content to 10.8 to 26.7 g/m². This precise parameter control prevents excessive inter-diffusion between iron and nickel, thereby reducing iron dissolution while maintaining the necessary diffusion layer for corrosion protection.
3Quantity of substance
If the nickel plating layer thickness is reduced, then the material cost and weight are reduced, but the corrosion resistance is decreased due to local iron exposure
Solution Approach 1:
The invention optimizes the nickel content parameter to a specific range (10.8 to 26.7 g/m²) and controls the diffusion layer thickness (0.03 to 0.50 μm) to ensure uniform nickel distribution. This prevents local iron exposure while using the minimum necessary nickel content, achieving both cost reduction and maintained corrosion resistance.
4Weight of moving object
If the can wall is made thinner to improve volume percentage, then the battery capacity to weight ratio is improved, but the processability is decreased due to increased iron dissolution
Solution Approach 1:
The invention controls the surface treatment parameters (diffusion layer thickness: 0.03 to 0.50 μm, total nickel content: 10.8 to 26.7 g/m²) to minimize iron dissolution. This enables thin-walled containers to be manufactured with good processability while achieving high volume percentage and reduced weight.
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 solution effectively improves corrosion resistance and processability of the steel sheet when formed into a battery container, preventing excessive iron exposure and gas generation, thus maintaining battery performance and capacity.
Implementation Method 1
the inter-diffusion between the iron in the steel sheet serving as a substrate and the nickel in the nickel plating layer
Data Source
AI summary
A surface-treated steel sheet for a battery container includes a steel sheet, an iron-nickel diffusion layer formed on the steel sheet, and a nickel layer formed on the iron-nickel diffusion layer and constituting the outermost layer. When the Fe intensity and the Ni intensity are continuously measured from the surface of the surface-treated steel sheet for a battery container along the depth direction with a high frequency glow discharge optical emission spectrometric analyzer, the thickness of the iron-nickel diffusion layer being the difference (D2−D1) between the depth (D1) at which the Fe intensity exhibits a first predetermined value and the depth (D2) at which the Ni intensity exhibits a second predetermined value is 0.04 to 0.31 μm; and the total amount of the nickel contained in the iron-nickel diffusion layer and the nickel contained in the nickel layer is 10.8 to 26.7 g/m2.