You get a charging cable with the batteries, USB-A on one side and 4x USB-C on the other. You can plug USB-A into any USB-A mobile phone charger or PC and charge it. USB-C goes to the batteries ;-) What you must not do: Charge the batteries in a charger for NiMh/NiCa batteries (especially for old "rechargeable batteries").
With the batteries you get a charging cable with USB-C/USB-A input for more convenience. The split cable branches out into 4 USB-C ports for charging each Zithion-X battery.