Ni-Co-Fe Diffusion Alloy Plating for Battery Containers
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Solution Overview
Problem
Surface-treated steel sheets for alkaline battery containers face challenges in maintaining discharge characteristics and liquid leakage resistance due to issues with Ni—Co plating, including increased charge transfer resistance and Co dissolution, which affects battery performance and workability during can shaping.
Innovation Solution
A surface-treated steel sheet with a Ni—Co—Fe-based diffusion alloy plating layer, comprising a Ni—Fe alloy layer and a Ni—Co—Fe alloy layer, is formed by diffusing Fe from the steel base into the plating layer, with specific coating weights and concentrations of Ni and Co to enhance adhesiveness and prevent cracking, while maintaining battery characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Ni—Co alloy plating layer is formed to improve discharge characteristics, then charge transfer resistance decreases, but the plating layer may crack during can shaping reducing workability
Solution Approach 1:
The patent uses a composite plating structure where the Ni-Fe alloy lower layer acts as a flexible, crack-resistant foundation with good ductility, while the Ni-Co alloy upper layer provides the desired electrical properties. The layered composite structure absorbs stress during can shaping, preventing cracks that would otherwise occur in a single-layer Ni-Co plating, thus improving workability while maintaining low charge transfer resistance.
Solution Approach 2:
The patent optimizes the thickness and composition parameters of each layer to balance electrical performance and mechanical flexibility. By controlling the Ni-Co alloy layer thickness and Co content, the patent achieves sufficient charge transfer performance while the underlying Ni-Fe layer provides mechanical flexibility to prevent cracking during deformation in can shaping operations.
2Reliability
If Co plating is applied to prevent Ni oxidation, then oxidation resistance is improved, but manufacturing cost increases due to expensive Co usage
Solution Approach 1:
The patent creates a cost-effective composite plating system where the expensive Co is concentrated in a thin upper layer (0.03-0.15 μm) that provides oxidation resistance, while the lower layer uses cheaper Ni-Fe alloy. This composite structure achieves the required oxidation protection with minimal Co usage, significantly reducing manufacturing cost compared to applying a thick uniform Co layer.
Solution Approach 2:
The patent applies Co selectively in the upper layer where oxidation resistance is most needed, while using cost-effective Ni-Fe alloy in the lower layer for adhesion and general corrosion resistance. This local quality approach ensures oxidation protection is provided only where necessary, minimizing expensive Co consumption while maintaining performance.
3Strength
If a thick Ni plating layer is used to ensure adequate coating weight, then adhesion is improved, but the total coating weight exceeds 9.0 g/m2 increasing cost and reducing efficiency
Solution Approach 1:
The patent replaces part of the traditional thick Ni plating with a Ni-Fe alloy layer containing Fe from the steel substrate through diffusion. This composite layer provides equivalent or superior adhesion to the steel substrate while reducing the total plating material weight below 9.0 g/m2. The Fe diffusion creates a gradient structure that enhances bonding without requiring excessive Ni coating weight.
Solution Approach 2:
The patent changes the composition and structure of the lower plating layer by introducing Fe diffusion from the steel substrate. This creates a Ni-Fe alloy layer with optimized adhesion properties that requires less total coating weight than conventional pure Ni plating, reducing material cost and improving manufacturing efficiency while maintaining strong adhesion.
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 provides a steel sheet with improved workability, liquid leakage resistance, and battery performance by reducing charge transfer resistance and preventing Co dissolution, while also reducing the usage of expensive Co and maintaining battery stability during shaping.
Implementation Method 1
the diffusion alloy plating layer is consisted of a Ni—Fe alloy layer and a Ni—Co—Fe alloy layer, which are arranged sequentially from the base steel sheet side; the diffusion alloy plating layer has a Ni coating weight within a range of 3.0 g/m2 or more and less than 8.74 g/m2 and a Co coating weight within a range of 0.26 g/m2 or more and 1.6 g/m2 or less
Data Source
AI summary
To provide a surface-treated steel sheet for battery containers excellent in workability while maintaining battery characteristics and liquid leakage resistance, and a manufacturing method thereof. A surface-treated steel sheet for battery containers according to the present invention includes a Ni—Co—Fe-based diffusion alloy plating layer on at least one surface of a base steel sheet, in which the diffusion alloy plating layer is consisted of a Ni—Fe alloy layer and a Ni—Co—Fe alloy layer, which are arranged sequentially from the base steel sheet side, the diffusion alloy plating layer has a Ni coating weight within a range of 3.0 g/m2 or more and less than 8.74 g/m2 and a Co coating weight within a range of 0.26 g/m2 or more and 1.6 g/m2 or less, with a total of the Ni coating weight and the Co coating weight being less than 9.0 g/m2, when a surface of the diffusion alloy plating layer is analyzed by an X-ray photoelectron spectroscopy, Co: 19.5 to 60%, Fe: 0.5 to 30%, and Co+Fe: 20 to 70% in atom % are satisfied, and a thickness of the Ni—Fe alloy layer is within a range of 0.3 to 1.3 μm.