Fully electric vehicles are exempt from the Czech motorway vignette. Your vehicle must be registered in advance in the official Czech e-vignette system (eDalnice).
Important: Hybrid vehicles are not exempt and require an e-vignette just like petrol and diesel cars.
Vehicles with a maximum permissible weight of over 3.5 tonnes (incl. combo of vehicle + trailer) use a distance-based toll system (MYTO CZ) instead of the e-vignette.
Related articles:
eDalnice contact information (Czech authority)
What vehicles need a Czech e-vignette?
Which roads require a Czech e-vignette?