Cu-Ni Clad Lead Material for Negative Electrode
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Solution Overview
Problem
The bonding strength of lead materials for negative electrodes decreases when welded to electrodes or terminals due to the formation of thick oxide films on the Ni layers during annealing in atmospheric conditions.
Innovation Solution
A lead material with Ni layers bonded to Cu layers, where the Ni layers have oxide films with thicknesses of 30 nm or less, and a manufacturing method involving annealing in a non-oxidizing atmosphere to reduce oxide film thickness and internal stress, allowing for improved bonding and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the clad material is annealed by heating in the atmosphere, then the internal stress is reduced and the material becomes more flexible, but the oxide film thickness increases and bonding strength decreases
Solution Approach 1:
The patent applies inert atmosphere annealing by heating the clad material in a non-oxidizing atmosphere (such as nitrogen or vacuum) to prevent oxide film formation on the Ni layer surfaces. This resolves the contradiction by maintaining bonding strength (preventing oxide formation) while still achieving stress reduction and flexibility improvement through the annealing process itself.
2Length of moving object
If rolling and annealing are repeated to thin the lead material, then the thickness is reduced to predetermined levels, but the oxide film thickness increases and bonding strength decreases
Solution Approach 1:
The patent performs the final annealing step in a non-oxidizing atmosphere to prevent oxide film formation on the thinned material. This allows the material to achieve the required thin dimensions through repeated rolling and annealing while maintaining bonding strength by preventing oxidation during the crucial final annealing stage.
Solution Approach 2:
The patent performs preliminary rolling steps to reduce thickness before the final annealing in non-oxidizing atmosphere. By doing most of the thinning work beforehand and performing only a light final annealing in protective atmosphere, the oxide film formation is minimized while still achieving the target thickness and necessary stress relief.
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
Significantly reduces the decrease in bonding strength and allows for easier welding and deformation of the lead material, enhancing its handleability and performance in batteries.
Implementation Method 1
an oxide film with a thickness of 30 nm or less
Implementation Method 2
performing annealing in a non-oxidizing atmosphere on the clad material
Data Source
AI summary
A lead material (5) for a negative electrode is made of a clad material (50) including a Cu layer (51) made of Cu or a Cu alloy and Ni layers (52, 53) each made of Ni or a Ni alloy. The Ni layers are respectively bonded to opposite surfaces of the Cu layer. The Ni layers each include a surface (52b, 53b) not bonded to the Cu layer, the surface including an oxide film (52c, 53c) with a thickness of 30 nm or less.