A:Answer Battery charger is NOT included! When these first came out they included a 45W adapter. There are plenty of unboxing videos on YouTube showing it.
45W is the Maximum claimed/designed speed. Slower speeds should work jus fine. But... look for PD 3.0 as your best option.
Per the User Manual
Power Adapter**
• 5~11V/4.5A (45W max) USB-C® AC adapter, supports PD 3.0, PPS, 100-240V, 50-60Hz
• 10V/2A (20W) AC adapter, 100-240V, 50-60Hz
But... Apparently nobody includes chargers any more. OEM's love to hype their supposed fast charge capabilities, but don't bother giving you a charger capable of the claimed speed.
I found the Lenovo 68W charger (it's cheaper than their 45W) on sale through their website (it's currently out of stock), and it seems to work very well and consistently maintains a 40-42W charge rate. A well known leading competitors 45W charger does not consistently maintain high speed charging, and after only a few seconds at 32-33W repeatedly resets dropping back down to 0W then slowly climbing back up (per AccuBattery App).