You can create price alert here, copy coupons and view price history. Let’s see what best price is ATM.
Working voltage 2.75 – 4.2V, Internal resistance less than 20 mΩ, Rechargeable time up to 500 times, Standard charge 0.3A~2A (Recommend 0.5A~1.5A), Brand Shockli, / 4.2V+/-0.05V, Name 21700 Rechargeable Battery, Protected No, Charging time 5.5 hours(Charge current 1.0A), Head type Flat top, Rechargeable battery Yes, Nominal voltage 3.7V, Capacity 4550mAh, Continuous /Max Discharge Current 22A/30A
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China. There are no active coupons for this product, but the price is pretty low isn’t it?
Link: Banggood product page
Price: $-3
It looks like this item is out of stock in Banggood. If you found it then please send me the link. I will replace it.
Click here to search on Banggood!
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BGTORCH, BGdragonBoat, bGhOnEy10, bgshOOp10, BgoFErTaSchInA10, BgcLuBofErtA10, BGFLS15, BGAFF10OFF, BGCuponation10, 4BLF, BGHONEY2110, BG10OFFAFF, BGwhielabel, BG10OFFAFF1, BGFLBA, BANGGOODSD, 6GSGIT, BGTorch4, 00c906, BGtorch2, BGtorch3, BGAlerabat15, BGtorch7
(sometimes old coupons work, so you can check them out (this site checks them on every price update))
Price history and price alert
Do you need price history chart (for all/most countries) for 2Pcs Shockli 21700 Battery 4550mAh Flat top 22A 3.7V? There we go.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood and Aliexpress (only if product name will be the same as on Banggood and I will post it on social media though, so it’s more like Banggood price alert)).