Overcharging the battery is not possible. Electric vehicles come with sophisticated battery charging technology to ensure that you battery is charged in an efficient and safe manner. The software will limit charging when the car reaches it's limit, which is either it's capacity (100%) or the charge limit that you specify.
Related FAQs:
https://electrictogether.com/get-help/what-is-an-electric-cars-battery-life
https://electrictogether.com/get-help/will-an-ev-battery-need-replacing-over-time