A 3.7V 9000mAh battery is a high-capacity lithium-ion (Li-ion) or lithium-polymer (Li-Po) cell designed for devices that require long runtimes. Because a single standard 18650 cell usually caps out at 3500mAh, a 9000mAh rating typically indicates a multi-cell pack (connected in parallel) or a larger format cell like a 32700 (LiFePO4) or a flat Li-Po pouch.Technical ProfileVoltage: 3.7V (Nominal), 4.2V (Fully Charged).Energy Capacity: 33.3 Wh (Watt-hours), calculated as $3.7\text{V} \times 9\text{Ah}$.Chemistry: Typically Lithium-Cobalt or Lithium-Polymer, offering high energy density.