Sputtered Chromium Lead Tab Coating for Adhesion and Corrosion Resistance
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Solution Overview
Problem
Conventional surface treatment methods for lead tabs in secondary batteries using hexavalent chromium are regulated due to human health and environmental hazards, necessitating the development of an alternative solution that enhances adhesion and prevents corrosion and peeling.
Innovation Solution
A lead tab comprising a copper substrate with a nickel-plated layer and a metal layer containing 70 to 99.9 wt% chromium, formed through a sputtering process, which improves adhesion strength to 1.4 N/mm or more, reducing hexavalent chromium usage and enhancing corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hexavalent chromium surface treatment is used, then adhesion and corrosion resistance are improved, but human health and environmental hazards increase
Solution Approach 1:
The invention changes the chemical composition parameters of the surface treatment layer, replacing hexavalent chromium with trivalent chromium and adjusting the chromium content to 5-20 micrometers thickness. This parameter change maintains the protective function while eliminating the harmful hexavalent chromium component, thus resolving the contradiction between reliability improvement and harmful factor reduction
Solution Approach 2:
The invention creates a composite surface treatment structure consisting of multiple layers including zinc-nickel alloy base layer and chromium oxide protective layer. This composite material approach provides both the adhesion/corrosion resistance functionality and the environmental safety by using non-toxic trivalent chromium instead of hexavalent chromium
2Reliability
If conventional surface treatment methods are used, then adhesion is achieved, but peeling and corrosion defects occur in actual use environments
Solution Approach 1:
The invention applies preliminary surface treatment by forming a zinc-nickel alloy plating layer before chromium oxidation. This preliminary action creates a stable, corrosion-resistant base that prevents subsequent peeling and corrosion defects, ensuring long-term adhesion stability in actual use environments
Solution Approach 2:
The invention optimizes the chromium layer thickness parameter to 5-20 micrometers and controls the chromium content composition to achieve the optimal balance between adhesion strength and corrosion/peeling resistance. This parameter optimization ensures the surface treatment maintains both initial adhesion and long-term stability
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 improved adhesion and corrosion resistance, preventing defects such as peeling and corrosion in actual use environments, while minimizing environmental and health risks associated with hexavalent chromium.
Implementation Method 1
formed through a sputtering process
Data Source
Figure 1~2
Figure 3
AI summary
Another embodiment of the present invention provides a lead tab comprising: a metal substrate including copper; a nickel-plated layer disposed on both sides of the metal substrate; and a metal layer on the nickel-plated layer, wherein the metal layer comprises 70 to 99.9 wt% of chromium and wherein the lead tab has an adhesive strength of 1.4 N/mm or more.