Surface-Treated Steel Sheet for Battery Containers
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Solution Overview
Problem
The existing methods for producing battery containers with iron-nickel alloy plating layers face issues with iron elution due to differences in standard electrode potential, leading to cracks and reduced service life, especially when the content ratio of Fe atoms is either too high or too low.
Innovation Solution
A method involving forming an iron-nickel alloy plating layer on a steel sheet, followed by a nickel plating layer, and then a thermal treatment to create an outermost iron-nickel alloy layer with a controlled Fe atom content ratio of 12 to 55% by atom, which suppresses iron elution and enhances surface hardness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the content ratio of Fe atoms is too high in the iron-nickel alloy plating layer, then the surface hardness is improved, but iron elution is suppressed poorly leading to reduced battery service life
Solution Approach 1:
The invention applies local quality by creating distinct regions within the plating structure: the iron-nickel alloy plating layer near the steel sheet provides hardness through high Fe content, while the nickel plating layer at the outermost surface provides corrosion resistance through high Ni content. This spatial differentiation of composition resolves the contradiction between surface hardness and iron elution suppression.
Solution Approach 2:
The invention uses composite materials by combining iron-nickel alloy and nickel in a layered structure. The iron-nickel alloy plating layer (15-65 at% Fe) provides mechanical properties, while the nickel plating layer (0.1-0.5 μm thickness) provides chemical stability. This composite approach allows simultaneous achievement of surface hardness and corrosion resistance.
2Reliability
If the content ratio of Fe atoms is too low in the iron-nickel alloy plating layer, then iron elution is suppressed well, but deep cracks occur during forming leading to steel sheet exposure and increased iron elution
Solution Approach 1:
The invention applies local quality by creating distinct regions within the plating structure: the iron-nickel alloy plating layer near the steel sheet provides hardness through high Fe content, while the nickel plating layer at the outermost surface provides corrosion resistance through high Ni content. This spatial differentiation of composition resolves the contradiction between surface hardness and iron elution suppression.
Solution Approach 2:
The invention uses composite materials by combining iron-nickel alloy and nickel in a layered structure. The iron-nickel alloy plating layer (15-65 at% Fe) provides mechanical properties, while the nickel plating layer (0.1-0.5 μm thickness) provides chemical stability. This composite approach allows simultaneous achievement of surface hardness and corrosion resistance.
3Reliability
If a nickel plating layer is formed on the iron-nickel alloy plating layer, then iron elution is suppressed, but the difference in standard electrode potential causes deep cracks during forming
Solution Approach 1:
The invention applies parameter changes by precisely controlling the thickness of the nickel plating layer (0.1-0.5 μm) and the Fe content in the iron-nickel alloy plating layer (15-65 at%). This parameter optimization ensures sufficient nickel coverage for elution suppression while maintaining adequate ductility to prevent deep cracks during battery container forming.
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 approach effectively extends the battery's service life and improves discharge characteristics by preventing iron elution and corrosion, while maintaining appropriate surface hardness to prevent deep cracks.
Implementation Method 1
a third process of performing a thermal treatment after forming the nickel plating layer to form an iron-nickel alloy layer having an outermost surface at which the content ratio of Fe atoms is 12 to 55% by atom, on an outermost layer by thermal diffusion
Data Source
AI summary
Provided is a method for producing a surface-treated steel sheet for battery containers including: a first process of forming an iron-nickel alloy plating layer on at least one side of a steel sheet; a second process of forming a nickel plating layer on the iron-nickel alloy plating layer; and a third process of performing a thermal treatment after forming the nickel plating layer to form an iron-nickel alloy layer having an outermost surface, at which a content ratio of Fe atoms is 12 to 55% by atom, on an outermost layer by thermal diffusion. The invention makes it possible to provide the method for producing the surface-treated steel sheet for battery containers that can suppress the elution of iron inside the battery when being used for a battery container, whereby the service life of the battery can be extended and battery characteristics such as discharge characteristics can be improved.