Not 18650 but related. Recently I've been salvaging li ions from disposable vapes. Usually they are between 2.6 and 3.3v depending on how long it's been sitting. This one was at 1v.
Lithium Ion Polymer Battery - 3.7v, 900mAh
esp8266 - 3.7v to 3.3v voltage regulator - Electrical Engineering Stack Exchange
Can I use a 3.7V battery for a 3.3V board? - General Electronics - Arduino Forum
16340 Micro Usb Power Bank Battery Charger Module Dual Output 3.3v 5v Rechargeable Battery Holder Lithium Battery Charging Board - Integrated Circuits - AliExpress
Buy Wholesale China 26650 3.3v 3000mah Li-ion Rechargeable Cylindrical Battery Lithium Battery Lifepo4 Battery & Lithium Battery at USD 30 | Global Sources
32650 26650 Rechargeable Solar 3.2v Lifepo4 Cell 3.3v Li-ion Lithium Li Ion Phosphate Battery 3000mah 3300mah 4000mah - Buy Lithium Ion Battery,3.3v Li-ion Lithium Ion Battery,32650 26650 3.2v Lifepo4 Cell Li Ion
18650 Li-ion Battery (3.3V/1500mAh) - China 18650 Lithium Battery and 18650 Cell
LithiumWerks ANR26650M1-B, 3.3 Volt, 2.5 Ah, Lithium Iron Phosphate (LiFePO4) Battery using Li-Ion NanoPhosphate® Technology
Welded CR2025 3V 3.3V Lithium Button Battery with Tabs Vertical Mounting Type CR 2025|Button Cell Batteries| - AliExpress
LithiumWerks ANR26650M1-B, 3.3 Volt, 2.5 Ah, Lithium Iron Phosphate (LiFePO4) Battery using Li-Ion NanoPhosphate® Technology
28 A123 System ANR26650M1B LiFePO4 26650 3.3V 2500 mAh Battery LiFe | eBay
ProTek RC 2x1S Sport Race 15C Stick LiFe Battery (3.3V/500mAh) (Kyosho Mini-Z) [PTK-5182] - AMain Hobbies