Don't buy batteries on ebay. It could be a used battery or a scam. You need a genuine Dell Replacement battery that is never been used. Get from Dell or a trusted source. 

https://www.dell.com/en-us/work/shop/accessories/apd/kwffn

You can also try removing the dead battery and using the adapter alone. The laptop will then be a desktop replacement.

Thank you Mary G for your reply

but i would just know if the 7.4V is compatible with my computer because i can't buy from dell official site (i'm from morocco) and I don't know if I can buy an 7.4v battery

Have you tried running the computer with the battery removed using just the adapter? 

The Dell battery lists 7.4 voltage on a resale site, but it says the computer must use 7.4.  Your dead battery says 11.1 which sounds like it is the other 3 cell battery. Sorry I couldn't help.

Yes the laptop is perfectly functional without the battery 

anyways thank you for your time