Amazon.com: Synergy Digital CMOS/BIOS Battery, Compatible with IBM Thinkpad 600 2645-51A CMOS/BIOS, (Lithium, 3V, 200mAh) Ultra High Capacity, Replacement for IBM 02K6486 Battery : Health & Household
IBM - ThinkPad 600 Battery | Complete Battery Source
Teardown battery safety Case & Cells: IBM ThinkPad 600 series | PANASONIC Li-ion Cell`s - YouTube