# Lap Welding of Nickel-Plated Steel and Copper Sheets Using Coaxial Laser Beams

## TL;DR

This study explores using coaxial laser beams to improve welding between nickel-plated steel and copper sheets, which is important for next-gen lithium batteries.

## Contribution

The use of a coaxial laser combining fiber and blue-light lasers enables high-quality welding of copper and nickel-plated steel.

## Key findings

- A YAG laser alone cannot weld the bottom copper sheet due to low absorption.
- Combining fiber and blue-light lasers in a coaxial setup improves weld quality and eliminates defects.
- The method shows promise for mass production in lithium battery manufacturing.

## Abstract

The laser heterogeneous lap welding of nickel-plated steel and Cu sheets has been investigated in this study. The YAG (Yttrium-Aluminum-Garnet) laser beam only penetrates the upper Ni-plated steel sheet and cannot weld the bottom Cu sheet due to the low absorption coefficient of the YAG laser beam. Incorporating a blue-light and fiber laser into the coaxial laser beam significantly improves the quality of the weld fusion zone. The fiber laser beam can penetrate the upper nickel-plated steel sheet, and the blue-light laser beam can melt the bottom copper sheet. Introducing the blue-light laser to the coaxial laser beams overcomes the low reflectivity of the bottom copper sheet. The fiber/blue-light coaxial laser continuous welding can achieve the best integrity and defect-free welding. It shows potential in the mass production of the next generation of lithium batteries.