When sourcing batteries, you must prioritize Energy Density, Cycle Life, and Discharge Rates. For Lithium-ion batteries, ensure a cycle life of at least 500-1000 cycles for consumer electronics and 3000+ cycles for energy storage systems (ESS). Verify the Nominal Voltage and Rated Capacity (mAh/Ah) against third-party lab reports to ensure they meet the advertised specifications. For industrial applications, check the Internal Resistance, as lower resistance indicates better efficiency and less heat generation.