Chromium-Rich Lead Tab Coating for Adhesion Without Hexavalent Chromium

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Solution Overview

Problem

Existing surface treatment technologies using hexavalent chromium for secondary batteries are hazardous and environmentally hazardous, and there is a need for improved adhesion methods to prevent corrosion and peeling of lead tabs in secondary batteries.

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, to enhance adhesion and corrosion resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If hexavalent chromium is used for surface treatment, then adhesion and corrosion resistance are improved, but environmental and health hazards increase

Engineering Contradiction:

Improveadhesion and corrosion resistanceVSAvoidenvironmental and health hazards

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention changes the chemical composition parameters of the surface treatment layer, replacing hexavalent chromium with trivalent chromium and adding specific metal elements (Al, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, In, Ga, Ge, or Ag) to achieve the required adhesion and corrosion resistance without the harmful effects of hexavalent chromium

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite surface treatment layer comprising trivalent chromium combined with specific metal elements, forming a multi-element composite structure that provides both protective functionality and environmental safety

Inventive Principle:

Principle #40Composite materials

2Reliability

If conventional surface treatment is used, then adhesion is achieved, but peeling and corrosion occur under stimulation in actual use environment

Engineering Contradiction:

ImproveadhesionVSAvoidresistance to peeling and corrosion

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The invention optimizes the compositional parameters of the surface treatment layer by specifying precise content ranges for trivalent chromium (0.1-10 wt%) and various metal elements, which enhances both adhesion strength and resistance to peeling and corrosion under actual use conditions

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention applies different material compositions to different aspects of the surface treatment layer, with trivalent chromium providing base adhesion and specific metal elements providing enhanced corrosion and peeling resistance, creating localized functional zones within the coating

Inventive Principle:

Principle #3Local quality

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 lead tab achieves adhesion strength of 1.4 N/mm or more, preventing corrosion and peeling in secondary batteries, while reducing environmental and health risks associated with hexavalent chromium.

Implementation Method 1

formed through a sputtering process

Methodology Applied

Scientific EffectSputtering: Sputtering

Data Source

PatentUS20250392016A1Lead tab with improved adhesion

Publication Date: 2025.12.25 FLEXION CO LTD

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 an adhesive strength of 1.4 N/mm or more.