Use these strips to make your own batteries from 18650 and 21700 cells (intended for spot welding). Strips can be doubled up for higher current capability (spot weld one, then the second on top rather than two at once).
Pure nickel is a metal with excellent properties such as low-resistance, corrosion-resistance, high thermal and electrical conductivity..
This is the thickest strip that can be reliably spot welded with commonly available hobby grade spot welders.
Pure nickel has lower resistance than nickel plated steel, which means less heating and energy loss. You can easily differentiate them by using salt water, nickel plated steel will rust.