Chromium-Coated Lead Tab for Stronger Battery Tab Welding
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Solution Overview
Problem
Secondary batteries face issues with weakened bonding strength at the welding area between lead tabs and electrode tabs due to applied physical forces, leading to potential ignition or explosion risks when high currents flow.
Innovation Solution
A lead tab design comprising a copper substrate with a nickel-plated layer and a chromium-rich metal layer, formed through a sputtering process, enhancing adhesion and welding strength to above 48 kgf/mm².
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional lead tab structure is used, then the device complexity is low, but the welding strength is insufficient and bonding strength weakens under physical force
Solution Approach 1:
The lead tab employs a composite layered structure consisting of a copper substrate, nickel-plated layer, and chromium-containing metal layer. This composite structure combines the high electrical conductivity of copper with the superior adhesion and oxidation resistance of nickel and chromium, achieving welding strength of 48 kgf/mm² or more while maintaining structural integrity under physical force
Solution Approach 2:
Different layers of the lead tab are assigned specific functional properties: the copper substrate provides electrical conductivity, the nickel-plated layer provides adhesion and corrosion resistance, and the chromium-containing top layer provides oxidation resistance and welding performance. This local differentiation of material properties optimizes overall performance without unnecessary complexity
2Reliability
If the bonding strength at welding area is insufficient, then the device complexity remains low, but the reliability deteriorates under physical force and high current
Solution Approach 1:
The multi-layer composite structure (copper substrate + nickel-plated layer + chromium-containing metal layer) ensures reliable bonding under physical force and high current conditions. The chromium-containing top layer specifically enhances welding reliability with a content of 70-99.9 wt% chromium, achieving consistent welding strength of 48 kgf/mm² or more
Solution Approach 2:
The nickel-plated layer and chromium-containing metal layer serve as protective barriers that prevent direct exposure of the copper substrate to corrosive and oxidizing environments. This beforehand protection ensures that the bonding interface maintains its strength and reliability even when subjected to physical force and electrical stress
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 improved lead tab design significantly enhances bonding strength, reducing the risk of welding area failure and associated ignition or explosion hazards.
Implementation Method 1
formed through a sputtering process
Data Source
AI summary
Another embodiment of the present disclosure 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 a welding strength of 48 kgf/mm2 or more.