Ni-Co-Fe Alloy-Plated Steel Sheet for Low-Resistance Battery Cans
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Solution Overview
Problem
Existing Ni-plated steel sheets used in battery containers face issues such as environmental contamination from organic solvent-based coatings, high energy consumption for water-based coatings, oxidation leading to increased contact resistance, and inadequate alkali resistance, while Co-plated layers suffer from Co elution and degradation of battery characteristics.
Innovation Solution
A surface-treated steel sheet with a Ni-Co-Fe alloy-plated layer is developed, where Fe is diffused into the outermost layer through heat treatment, enhancing adhesion and scratch resistance, and the total coating weight of Ni and Co is maintained at 9.0 g/m² or more, using a low-carbon Al-killed steel sheet as the base.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Co-plated layer is applied on a Ni-plated layer to improve alkali resistance and reduce contact resistance, then the chemical stability and electrical conductivity are enhanced, but Co elution occurs over time causing degradation of battery characteristics
Solution Approach 1:
The patent applies local quality by creating a multi-layer plated structure where each layer has specific compositional characteristics. The Ni-Co alloy layer has a controlled Co/Ni ratio (0.1-1.5) in the outermost layer, while underlying layers have different compositions. This gradient structure provides Co protection where needed while preventing excessive Co elution, resolving the contradiction between improving alkali resistance and maintaining compositional stability.
Solution Approach 2:
The patent uses composite materials by combining Ni and Co in a controlled alloy structure with specific Co/Ni ratios. This composite plated layer integrates the chemical stability of Ni with the alkali resistance of Co, while the controlled composition prevents Co elution. The multi-layer composite structure resolves the contradiction by synergistically combining material properties.
2Stability of the object's composition
If a Ni-Co alloy layer is formed with controlled Co/Ni ratio to prevent Co elution, then battery characteristics are maintained, but the manufacturing process becomes more complex requiring precise composition control
Solution Approach 1:
The patent applies parameter changes by precisely controlling the Co/Ni ratio parameter in the plated layer outermost surface within the range of 0.1-1.5. By optimizing this compositional parameter, the patent achieves stable battery characteristics without excessive process complexity. The controlled parameter approach resolves the contradiction between composition stability and manufacturing simplicity.
3Reliability
If organic solvent-based coating is applied to enhance discharge characteristics, then contact with positive electrode mixture is maintained, but environmental contamination occurs
Solution Approach 1:
The patent replaces expensive and environmentally harmful organic solvent-based coatings with a metallic plated layer that provides durable protection without environmental contamination. The Ni-Co alloy plated layer serves as a long-lasting alternative to disposable organic coatings, resolving the contradiction between maintaining discharge characteristics and preventing environmental harm.
4Object-affected harmful factors
If water-based coating is used to avoid environmental contamination, then environmental friendliness is improved, but energy consumption for drying increases
Solution Approach 1:
The patent extracts the coating function entirely from organic or water-based chemical coatings and replaces it with a metallic plated layer deposited through electroplating. This eliminates the need for drying processes and associated energy consumption, while also avoiding environmental contamination. The extraction of the coating concept from chemical to metallic resolution the contradiction between environmental friendliness and energy efficiency.
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 steel sheet achieves improved chemical and mechanical characteristics, including reduced surface resistance, enhanced adhesion, and alkali resistance, while minimizing Co usage and maintaining the integrity of the base metal properties.
Implementation Method 1
a heat treatment is carried out to heat and diffuse the elements
Implementation Method 2
a heat treatment is carried out to heat and diffuse the elements
Implementation Method 3
a Ni-plated layer and a Co-plated layer are formed in this order on a surface of a steel sheet
Data Source
Figure 1A~1B
Figure 2
AI summary
A surface-treated steel sheet of the present invention includes a base steel sheet and a Ni-Co-Fe alloy-plated layer on at least one surface of the base steel sheet, in which, in the alloy-plated layer, a Ni coating weight is 7.1 to 18.5 g/m2, a Co coating weight is 0.65 to 3.6 g/m2, and a total of the Ni coating weight and the Co coating weight is in a range of 9.0 to 20.0 g/m2. In a surface layer of the alloy-plated layer, a Co concentration is in a range of 20 to 60 atom%, and a Fe concentration is in a range of 5 to 30 atom%. In the alloy-plated layer, a region having a thickness of 2 µm or more, in which a total of a Ni concentration and the Co concentration is 10 atom% or more and the Fe concentration is 5 atom% or more, is present. The base steel sheet has a predetermined chemical composition, and a ferrite grain size number is 10 or more.